Analysis of information sources in references of the Wikipedia article "Lisdexamfetamine" in English language version.
Our meta-analysis of the four RCT data sets (Guerdjikova et al., 2016; McElroy et al., 2015b; McElroy et al., 2016a) showed an overall significant effect of LDX on binge-eating symptom change. ...
BED has been described as an impulse control disorder since one of the key symptoms of the disorder is a lack of control over eating (American Psychiatric Association, 2013) and it is possible that LDX may be effective in treating BED at least in part by reducing impulsivity, compulsivity, and the repetitive nature of binge eating. There is extensive evidence that loss of impulse control in BED is a causal factor in provoking bingeing symptoms (Colles et al., 2008; Galanti et al., 2007; Giel et al., 2017; McElroy et al., 2016a; Nasser et al., 2004; Schag et al., 2013). More specifically, BED is associated with motor impulsivity and non-planning impulsivity which could initiate and maintain binge eating (Nasser et al., 2004). Neuroimaging studies using the Stroop task to measure impulse control have shown that BED patients have decreased BOLD fMRI activity in brain areas involved in self-regulation and impulse control including VMPFC, inferior frontal gyrus (IFG), and insula during performance of the task compared to lean and obese controls (Balodis et al., 2013b). ...
It is conceivable that in BED patients a low 30 mg dose of LDX could reduce food intake by suppressing appetite or enhancing satiety and higher (50 and 70 mg) doses of the drug may have a dual suppressant effect on food intake and binge-eating frequency.
All the amphetamines enhance activity at dopamine, noradrenaline and 5HT synapses. They cause presynaptic release of preformed transmitters, and also inhibit the re-uptake of dopamine and noradrenaline. These actions are most prominent in the brainstem ascending reticular activating system and the cerebral cortex.
The simplest unsubstituted phenylisopropylamine, 1-phenyl-2-aminopropane, or amphetamine, serves as a common structural template for hallucinogens and psychostimulants. Amphetamine produces central stimulant, anorectic, and sympathomimetic actions, and it is the prototype member of this class (39). ... The phase 1 metabolism of amphetamine analogs is catalyzed by two systems: cytochrome P450 and flavin monooxygenase. ... Amphetamine can also undergo aromatic hydroxylation to p-hydroxyamphetamine. ... Subsequent oxidation at the benzylic position by DA β-hydroxylase affords p-hydroxynorephedrine. Alternatively, direct oxidation of amphetamine by DA β-hydroxylase can afford norephedrine.
Onset of efficacy was earliest for d-MPH-ER at 0.5 hours, followed by d, l-MPH-LA at 1 to 2 hours, MCD at 1.5 hours, d, l-MPH-OR at 1 to 2 hours, MAS-XR at 1.5 to 2 hours, MTS at 2 hours, and LDX at approximately 2 hours. ... MAS-XR, and LDX have a long duration of action at 12 hours postdose
Basal ganglia regions like the right globus pallidus, the right putamen, and the nucleus caudatus are structurally affected in children with ADHD. These changes and alterations in limbic regions like ACC and amygdala are more pronounced in non-treated populations and seem to diminish over time from child to adulthood. Treatment seems to have positive effects on brain structure.
Several other studies,[97-101] including a meta-analytic review[98] and a retrospective study,[97] suggested that stimulant therapy in childhood is associated with a reduced risk of subsequent substance use, cigarette smoking and alcohol use disorders. ... Recent studies have demonstrated that stimulants, along with the non-stimulants atomoxetine and extended-release guanfacine, are continuously effective for more than 2-year treatment periods with few and tolerable adverse effects. The effectiveness of long-term therapy includes not only the core symptoms of ADHD, but also improved quality of life and academic achievements. The most concerning short-term adverse effects of stimulants, such as elevated blood pressure and heart rate, waned in long-term follow-up studies. ... The current data do not support the potential impact of stimulants on the worsening or development of tics or substance abuse into adulthood. In the longest follow-up study (of more than 10 years), lifetime stimulant treatment for ADHD was effective and protective against the development of adverse psychiatric disorders.
The highest proportion of improved outcomes was reported with combination treatment (83% of outcomes). Among significantly improved outcomes, the largest effect sizes were found for combination treatment. The greatest improvements were associated with academic, self-esteem, or social function outcomes.
The main efficacy-related conclusions of this review are: (a) medications demonstrated the strongest and most consistent effects on core ADHD symptoms (especially inattention), (b) heterogeneous C/BTs demonstrated inconsistent effects on ADHD symptoms, strong consistent effects on impairment and executive function skills, and modest consistent effects on internalizing symptoms and analogue note-taking performance, (c) C/BTs demonstrated consistent maintenance effects for executive function skills and impairment up to 6 months and possibly 3 years post-treatment, (d) though comparing the efficacy of two C/BTs rarely led to significant differences, which C/BT worked best for whom could be reliably predicted from patient- and provider-level moderators ...
Thus, maximal therapeutic benefit (in terms of breadth of response and maintenance of effects) might be achieved by combining medication and C/BTs, a recommendation generally reflected in current practice parameters (AACAP, 2007; AADPA, 2022; NICE, 2018; Wolraich et al., 2019).
We conducted the first systematic review and meta-analysis investigating the effects of medication for ADHD on quality of life (QoL) in parallel or crossover RCTs. Overall, we found that methylphenidate, amphetamines, and atomoxetine were significantly more efficacious than placebo in improving QoL in people with ADHD. ...
Four studies on amphetamines (950 participants with ADHD in total; 45% adults) reported relevant data for effect sizes to be computed. The meta-analysis on 14 effect sizes showed that amphetamines led to better QoL than placebo in individuals with ADHD.
Our findings were based on 113 RCTs, including 14 887 participants, and indicated that stimulants were the only intervention that was supported by evidence of efficacy in the short term (ie, at timepoints closest to 12 weeks) for core symptoms of ADHD in adults (both self-reported and clinician-reported) and was associated with good acceptability (all-cause discontinuation).
Only one paper53 examining outcomes beyond 36 months met the review criteria. ... There is high level evidence suggesting that pharmacological treatment can have a major beneficial effect on the core symptoms of ADHD (hyperactivity, inattention, and impulsivity) in approximately 80% of cases compared with placebo controls, in the short term.
BED subjects have substantial decrements in their ventral striatal reward pathways and diminished ability to recruit fronto-cortical impulse-control circuits to implement dietary restraint. ...
There is not only substantial overlap between the psychopathology of BED and ADHD but also a clear association between these two disorders. Lisdexamfetamine's ability to reduce impulsivity and increase cognitive control in ADHD supports the hypothesis that efficacy in BED is dependent on treating its core obsessive, compulsive and impulsive behaviours.
Genetic polymorphisms associated with abnormal dopaminergic signaling have been found in individuals who exhibit binge-eating behavior, and the binge-eating episodes,which often involve the consumption of highly palatable food, further stimulate the dopaminergic system. This ongoing stimulation may contribute to progressive impairments in dopamine signaling. Lisdexamfetamine is hypothesized to reduce binge-eating behavior by normalizing dopaminergic activity. ...
After 12 weeks, both studies found significant reductions in the number of binge-eating days per week in the active treatment group compared with placebo (P < .001 for both studies; Figure 1). Lisdexamfetamine was also found to be superior to placebo on a number of secondary outcome measures including global improvement, binge-eating cessation for 4 weeks, and reduction of obsessive-compulsive binge-eating symptoms, body weight, and triglycerides.
LDX is commonly used in the treatment of ADHD, and is the only treatment for BED that is approved by the Food and Drug Administration (FDA) and the Therapeutic Goods Administration (TGA). LDX, like all amphetamine stimulants, has direct appetite suppressant effects that may be therapeutically useful in BED, although long-term neuroadaptations in dopaminergic and noradrenergic systems caused by LDX may also be relevant, leading to improved regulation of eating behaviours, attentional processes and goal-directed behaviours. ...
Evidently, there is a substantial volume of trials with high-quality evidence supporting the efficacy of LDX in reducing binge eating frequency in treatment of adults with moderate to severe BED at 50–70 mg/day.
Stimulant medications may be especially effective for individuals with BED because of dual effects on reward and executive function systems. Indeed, the only FDA-approved pharmacotherapy for BED is LDX, a d-amphetamine prodrug. ...
In humans, RCTs found that LDX reduced binge eating and impulsivity/compulsivity symptoms. Notably, there is a strong correlation between compulsivity symptoms and severity/frequency of binge eating episodes observed in LDX trials. Further, in individuals with BED, changes in prefrontal brain systems associated with LDX treatment were related to treatment outcome.
Our meta-analysis of the four RCT data sets (Guerdjikova et al., 2016; McElroy et al., 2015b; McElroy et al., 2016a) showed an overall significant effect of LDX on binge-eating symptom change. ...
BED has been described as an impulse control disorder since one of the key symptoms of the disorder is a lack of control over eating (American Psychiatric Association, 2013) and it is possible that LDX may be effective in treating BED at least in part by reducing impulsivity, compulsivity, and the repetitive nature of binge eating. There is extensive evidence that loss of impulse control in BED is a causal factor in provoking bingeing symptoms (Colles et al., 2008; Galanti et al., 2007; Giel et al., 2017; McElroy et al., 2016a; Nasser et al., 2004; Schag et al., 2013). More specifically, BED is associated with motor impulsivity and non-planning impulsivity which could initiate and maintain binge eating (Nasser et al., 2004). Neuroimaging studies using the Stroop task to measure impulse control have shown that BED patients have decreased BOLD fMRI activity in brain areas involved in self-regulation and impulse control including VMPFC, inferior frontal gyrus (IFG), and insula during performance of the task compared to lean and obese controls (Balodis et al., 2013b). ...
It is conceivable that in BED patients a low 30 mg dose of LDX could reduce food intake by suppressing appetite or enhancing satiety and higher (50 and 70 mg) doses of the drug may have a dual suppressant effect on food intake and binge-eating frequency.
Peripheral norepinephrine concentration rises as well. As demonstrated after Dextroamphetamine administration, plasma norepinephrine can rise up to 400 pg/mL, a level comparable to that achieved during mild physical activity. Cumulative effect on norepinephrine concentration is likely when amphetamine-type medications are given in the setting of acute illness or combined with activities leading to catecholamine release, such as exercise. ... The primary effect of norepinephrine on ketogenesis is mediated through increased substrate availability. As shown by Krentz et al., at high physiological concentrations, norepinephrine induces accelerated lipolysis and increases NEFA formation significantly. Secondly, norepinephrine stimulates ketogenesis directly at the hepatocyte level. As reported by Keller et al., norepinephrine infusion increased ketone bodies concentration to a greater degree when compared to NEFA concentration (155 ± 30 versus 57 ± 16%), suggesting direct hepatic ketogenic effect.
An 11-week, double-blind RCT examined the effects of three doses of lisdexamfetamine (30 mg/day, 50 mg/day, 70 mg/day) and placebo on binge eating frequency. Results indicated that 50 mg and 70 mg doses were superior to placebo in reducing binge eating. Two follow-up 12-week RCTs confirmed the superiority of 50 and 70 mg doses to placebo in improving binge eating and secondary outcome measures, including obsessive–compulsive symptoms, body weight, and global improvement. ... Subsequent studies of lisdexamfetamine provided further support for the medication's safety and efficacy and provided additional evidence that continued use may be better than placebo in preventing relapse. While it is considered safe and effective, lisdexamfetamine's side effect profile and risk for misuse may make it inappropriate for certain patients.
Narcolepsy type 1 was called "narcolepsy with cataplexy" before 2014 (AASM, 2005), but was renamed NT1 in the third and last international classification of sleep disorders (AASM, 2014). ... A low level of Hcrt-1 in the CSF is very sensitive and specific for the diagnosis of NT1. ...
All patients with low CSF Hcrt-1 levels are considered as NT1 patients, even if they report no cataplexy (in about 10–20% of cases), and all patients with normal CSF Hcrt-1 levels (or without cataplexy when the lumbar puncture is not performed) as NT2 patients (Baumann et al., 2014). ...
In patients with NT1, the absence of Hcrt leads to the inhibition of regions that suppress REM sleep, thus allowing the activation of descending pathways inhibiting motoneurons, leading to cataplexy.
At the pathophysiological level, it is now clear that most narcolepsy cases with cataplexy, and a minority of cases (5–30 %) without cataplexy or with atypical cataplexy-like symptoms, are caused by a lack of hypocretin (orexin) of likely an autoimmune origin. In these cases, once the disease is established, the majority of the 70,000 hypocretin-producing cells have been destroyed, and the disorder is irreversible. ...
Amphetamines are exceptionally wake-promoting, and at high doses also reduce cataplexy in narcoleptic patients, an effect best explained by its action on adrenergic and serotoninergic synapses. ...
The D-isomer is more specific for DA transmission and is a better stimulant compound. Some effects on cataplexy (especially for the L-isomer), secondary to adrenergic effects, occur at higher doses. ...
Numerous studies have shown that increased dopamine release is the main property explaining wake-promotion, although norepinephrine effects also contribute.
Alertness and associated forebrain and cortical arousal are mediated by several ascending pathways with distinct neuronal components that project from the upper brain stem near the junction of the pons and the midbrain. ...
Key cell populations of the ascending arousal pathway include cholinergic, noradrenergic, serotoninergic, dopaminergic, and histaminergic neurons located in the pedunculopontine and laterodorsal tegmental nucleus (PPT/LDT), locus coeruleus, dorsal and median raphe nucleus, and tuberomammillary nucleus (TMN), respectively. ...
The mechanism of action of sympathomimetic alerting drugs (eg, dextro- and methamphetamine, methylphenidate) is direct or indirect stimulation of dopaminergic and noradrenergic nuclei, which in turn heightens the efficacy of the ventral periaqueductal grey area and locus coeruleus, both components of the secondary branch of the ascending arousal system. ...
Sympathomimetic drugs have long been used to treat narcolepsy
The TF identified 1 double-blind RCT, 1 single-blind RCT, and 1 retrospective observational long-term self-reported case series assessing the efficacy of dextroamphetamine in patients with narcolepsy type 1 and narcolepsy type 2. These studies demonstrated clinically significant improvements in excessive daytime sleepiness and cataplexy.
The usefulness of amphetamines is limited by a potential risk of abuse, and their cardiovascular adverse effects (Table 1). That is why, even though they are cheaper than other drugs, and efficient, they remain third-line therapy in narcolepsy. Three class II studies showed an improvement of EDS in that disease. ...
Despite the potential for drug abuse or tolerance using stimulants, patients with narcolepsy rarely exhibit addiction to their medication. ...
Some stimulants, such as mazindol, amphetamines, and pitolisant, may also have some anticataplectic effects.
Recent clinical trials and practice guidelines have confirmed that stimulants such as modafinil, armodafinil, or sodium oxybate (as first line); methylphenidate and pitolisant (as second line [pitolisant is currently only available in Europe]); and amphetamines (as third line) are appropriate medications for excessive daytime sleepiness.
The first agents used to treat EDS (ie, amphetamines, methylphenidate) are now considered second- or third-line options because newer medications have been developed with improved tolerability and lower abuse potential (eg, modafinil/armodafinil, solriamfetol, pitolisant)
The procognitive actions of psychostimulants are only associated with low doses. Surprisingly, despite nearly 80 years of clinical use, the neurobiology of the procognitive actions of psychostimulants has only recently been systematically investigated. Findings from this research unambiguously demonstrate that the cognition-enhancing effects of psychostimulants involve the preferential elevation of catecholamines in the PFC and the subsequent activation of norepinephrine α2 and dopamine D1 receptors. ... This differential modulation of PFC-dependent processes across dose appears to be associated with the differential involvement of noradrenergic α2 versus α1 receptors. Collectively, this evidence indicates that at low, clinically relevant doses, psychostimulants are devoid of the behavioral and neurochemical actions that define this class of drugs and instead act largely as cognitive enhancers (improving PFC-dependent function). ... In particular, in both animals and humans, lower doses maximally improve performance in tests of working memory and response inhibition, whereas maximal suppression of overt behavior and facilitation of attentional processes occurs at higher doses.
Specifically, in a set of experiments limited to high-quality designs, we found significant enhancement of several cognitive abilities. ... The results of this meta-analysis ... do confirm the reality of cognitive enhancing effects for normal healthy adults in general, while also indicating that these effects are modest in size.
Amphetamine has been shown to improve consolidation of information (0.02 ≥ P ≤ 0.05), leading to improved recall.
misuse of prescription stimulants has become a serious problem on college campuses across the US and has been recently documented in other countries as well. ... Indeed, large numbers of students claim to have engaged in the nonmedical use of prescription stimulants, which is reflected in lifetime prevalence rates of prescription stimulant misuse ranging from 5% to nearly 34% of students.
Overall, the data suggest that ADHD medication misuse and diversion are common health care problems for stimulant medications, with the prevalence believed to be approximately 5% to 10% of high school students and 5% to 35% of college students, depending on the study.
Amphetamines and caffeine are stimulants that increase alertness, improve focus, decrease reaction time, and delay fatigue, allowing for an increased intensity and duration of training ...
Physiologic and performance effects
• Amphetamines increase dopamine/norepinephrine release and inhibit their reuptake, leading to central nervous system (CNS) stimulation
• Amphetamines seem to enhance athletic performance in anaerobic conditions 39 40
• Improved reaction time
• Increased muscle strength and delayed muscle fatigue
• Increased acceleration
• Increased alertness and attention to task
In 1980, Chandler and Blair47 showed significant increases in knee extension strength, acceleration, anaerobic capacity, time to exhaustion during exercise, pre-exercise and maximum heart rates, and time to exhaustion during maximal oxygen consumption (VO2 max) testing after administration of 15 mg of dextroamphetamine versus placebo. Most of the information to answer this question has been obtained in the past decade through studies of fatigue rather than an attempt to systematically investigate the effect of ADHD drugs on exercise.
In high-ambient temperatures, dopaminergic manipulations clearly improve performance. The distribution of the power output reveals that after dopamine reuptake inhibition, subjects are able to maintain a higher power output compared with placebo. ... Dopaminergic drugs appear to override a safety switch and allow athletes to use a reserve capacity that is 'off-limits' in a normal (placebo) situation.
Manipulations of dopaminergic signaling profoundly influence interval timing, leading to the hypothesis that dopamine influences internal pacemaker, or "clock," activity. For instance, amphetamine, which increases concentrations of dopamine at the synaptic cleft advances the start of responding during interval timing, whereas antagonists of D2 type dopamine receptors typically slow timing;... Depletion of dopamine in healthy volunteers impairs timing, while amphetamine releases synaptic dopamine and speeds up timing.
Aside from accounting for the reduced performance of mentally fatigued participants, this model rationalizes the reduced RPE and hence improved cycling time trial performance of athletes using a glucose mouthwash (Chambers et al., 2009) and the greater power output during a RPE matched cycling time trial following amphetamine ingestion (Swart, 2009). ... Dopamine stimulating drugs are known to enhance aspects of exercise performance (Roelands et al., 2008)
This indicates that subjects did not feel they were producing more power and consequently more heat. The authors concluded that the "safety switch" or the mechanisms existing in the body to prevent harmful effects are overridden by the drug administration (Roelands et al., 2008b). Taken together, these data indicate strong ergogenic effects of an increased DA concentration in the brain, without any change in the perception of effort.
Inactive lisdexamfetamine is completely (>98%) converted to its active metabolite D-amphetamine in the circulation (Pennick, 2010; Sharman and Pennick, 2014). When lisdexamfetamine is misused intranasally or intravenously, the pharmacokinetics are similar to oral use (Jasinski and Krishnan, 2009b; Ermer et al., 2011), and the subjective effects are not enhanced by parenteral administration in contrast to D-amphetamine (Lile et al., 2011) thus reducing the risk of parenteral misuse of lisdexamfetamine compared with D-amphetamine. Intravenous lisdexamfetamine use also produced significantly lower increases in "drug liking" and "stimulant effects" compared with D-amphetamine in intravenous substance users (Jasinski and Krishnan, 2009a).
VMAT2 is the CNS vesicular transporter for not only the biogenic amines DA, NE, EPI, 5-HT, and HIS, but likely also for the trace amines TYR, PEA, and thyronamine (THYR) ... [Trace aminergic] neurons in mammalian CNS would be identifiable as neurons expressing VMAT2 for storage, and the biosynthetic enzyme aromatic amino acid decarboxylase (AADC).
Despite the challenges in determining synaptic vesicle pH, the proton gradient across the vesicle membrane is of fundamental importance for its function. Exposure of isolated catecholamine vesicles to protonophores collapses the pH gradient and rapidly redistributes transmitter from inside to outside the vesicle. ... Amphetamine and its derivatives like methamphetamine are weak base compounds that are the only widely used class of drugs known to elicit transmitter release by a non-exocytic mechanism. As substrates for both DAT and VMAT, amphetamines can be taken up to the cytosol and then sequestered in vesicles, where they act to collapse the vesicular pH gradient.
Three important new aspects of TAs action have recently emerged: (a) inhibition of firing due to increased release of dopamine; (b) reduction of D2 and GABAB receptor-mediated inhibitory responses (excitatory effects due to disinhibition); and (c) a direct TA1 receptor-mediated activation of GIRK channels which produce cell membrane hyperpolarization.
AMPH also increases intracellular calcium (Gnegy et al., 2004) that is associated with calmodulin/CamKII activation (Wei et al., 2007) and modulation and trafficking of the DAT (Fog et al., 2006; Sakrikar et al., 2012). ... For example, AMPH increases extracellular glutamate in various brain regions including the striatum, VTA and NAc (Del Arco et al., 1999; Kim et al., 1981; Mora and Porras, 1993; Xue et al., 1996), but it has not been established whether this change can be explained by increased synaptic release or by reduced clearance of glutamate. ... DHK-sensitive, EAAT2 uptake was not altered by AMPH (Figure 1A). The remaining glutamate transport in these midbrain cultures is likely mediated by EAAT3 and this component was significantly decreased by AMPH
AMPH and METH also stimulate DA efflux, which is thought to be a crucial element in their addictive properties [80], although the mechanisms do not appear to be identical for each drug [81]. These processes are PKCβ– and CaMK–dependent [72, 82], and PKCβ knock-out mice display decreased AMPH-induced efflux that correlates with reduced AMPH-induced locomotion [72].
Amphetamine is usually consumed via inhalation or orally, either in the form of a racemic mixture (levoamphetamine and dextroamphetamine) or dextroamphetamine alone (Childress et al. 2019). In general, all amphetamines have high bioavailability when consumed orally, and in the specific case of amphetamine, 90% of the consumed dose is absorbed in the gastrointestinal tract, with no significant differences in the rate and extent of absorption between the two enantiomers (Carvalho et al. 2012; Childress et al. 2019). The onset of action occurs approximately 30 to 45 minutes after consumption, depending on the ingested dose and on the degree of purity or on the concomitant consumption of certain foods (European Monitoring Centre for Drugs and Drug Addiction 2021a; Steingard et al. 2019). It is described that those substances that promote acidification of the gastrointestinal tract cause a decrease in amphetamine absorption, while gastrointestinal alkalinization may be related to an increase in the compound's absorption (Markowitz and Patrick 2017).
Dopamine-β-hydroxylase catalyzed the removal of the pro-R hydrogen atom and the production of 1-norephedrine, (2S,1R)-2-amino-1-hydroxyl-1-phenylpropane, from d-amphetamine.
Hydroxyamphetamine was administered orally to five human subjects ... Since conversion of hydroxyamphetamine to hydroxynorephedrine occurs in vitro by the action of dopamine-β-oxidase, a simple method is suggested for measuring the activity of this enzyme and the effect of its inhibitors in man. ... The lack of effect of administration of neomycin to one patient indicates that the hydroxylation occurs in body tissues. ... a major portion of the β-hydroxylation of hydroxyamphetamine occurs in non-adrenal tissue. Unfortunately, at the present time one cannot be completely certain that the hydroxylation of hydroxyamphetamine in vivo is accomplished by the same enzyme which converts dopamine to noradrenaline.
Figure 1. Glycine conjugation of benzoic acid. The glycine conjugation pathway consists of two steps. First benzoate is ligated to CoASH to form the high-energy benzoyl-CoA thioester. This reaction is catalyzed by the HXM-A and HXM-B medium-chain acid:CoA ligases and requires energy in the form of ATP. ... The benzoyl-CoA is then conjugated to glycine by GLYAT to form hippuric acid, releasing CoASH. In addition to the factors listed in the boxes, the levels of ATP, CoASH, and glycine may influence the overall rate of the glycine conjugation pathway.
The biologic significance of the different levels of serum DβH activity was studied in two ways. First, in vivo ability to β-hydroxylate the synthetic substrate hydroxyamphetamine was compared in two subjects with low serum DβH activity and two subjects with average activity. ... In one study, hydroxyamphetamine (Paredrine), a synthetic substrate for DβH, was administered to subjects with either low or average levels of serum DβH activity. The percent of the drug hydroxylated to hydroxynorephedrine was comparable in all subjects (6.5-9.62) (Table 3).
In species where aromatic hydroxylation of amphetamine is the major metabolic pathway, p-hydroxyamphetamine (POH) and p-hydroxynorephedrine (PHN) may contribute to the pharmacological profile of the parent drug. ... The location of the p-hydroxylation and β-hydroxylation reactions is important in species where aromatic hydroxylation of amphetamine is the predominant pathway of metabolism. Following systemic administration of amphetamine to rats, POH has been found in urine and in plasma.
The observed lack of a significant accumulation of PHN in brain following the intraventricular administration of (+)-amphetamine and the formation of appreciable amounts of PHN from (+)-POH in brain tissue in vivo supports the view that the aromatic hydroxylation of amphetamine following its systemic administration occurs predominantly in the periphery, and that POH is then transported through the blood-brain barrier, taken up by noradrenergic neurones in brain where (+)-POH is converted in the storage vesicles by dopamine β-hydroxylase to PHN.
This product (Dyanavel XR) is an oral suspension (i.e., a drug that is suspended in a liquid and taken by mouth) that contains 2.5 mg/mL of amphetamine base. The amphetamine base contains dextro- to levo-amphetamine in a ratio of 3.2:1, which is approximately the ratio in Adderall. The product uses an ion exchange resin to achieve extended release of the amphetamine base.
We conducted the first systematic review and meta-analysis investigating the effects of medication for ADHD on quality of life (QoL) in parallel or crossover RCTs. Overall, we found that methylphenidate, amphetamines, and atomoxetine were significantly more efficacious than placebo in improving QoL in people with ADHD. ...
Four studies on amphetamines (950 participants with ADHD in total; 45% adults) reported relevant data for effect sizes to be computed. The meta-analysis on 14 effect sizes showed that amphetamines led to better QoL than placebo in individuals with ADHD.
VMAT2 is the CNS vesicular transporter for not only the biogenic amines DA, NE, EPI, 5-HT, and HIS, but likely also for the trace amines TYR, PEA, and thyronamine (THYR) ... [Trace aminergic] neurons in mammalian CNS would be identifiable as neurons expressing VMAT2 for storage, and the biosynthetic enzyme aromatic amino acid decarboxylase (AADC).
Dopamine-β-hydroxylase catalyzed the removal of the pro-R hydrogen atom and the production of 1-norephedrine, (2S,1R)-2-amino-1-hydroxyl-1-phenylpropane, from d-amphetamine.
2. Qualitative and quantitative composition. 30 mg Capsules: Each capsule contains 30 mg lisdexamfetamine dimesylate, equivalent to 8.9 mg of dexamfetamine. 50 mg Capsules: Each capsule contains 50 mg lisdexamfetamine dimesylate, equivalent to 14.8 mg of dexamfetamine. 70 mg Capsules: Each capsule contains 70 mg lisdexamfetamine dimesylate, equivalent to 20.8 mg of dexamfetamine.
Onset of efficacy was earliest for d-MPH-ER at 0.5 hours, followed by d, l-MPH-LA at 1 to 2 hours, MCD at 1.5 hours, d, l-MPH-OR at 1 to 2 hours, MAS-XR at 1.5 to 2 hours, MTS at 2 hours, and LDX at approximately 2 hours. ... MAS-XR, and LDX have a long duration of action at 12 hours postdose
Basal ganglia regions like the right globus pallidus, the right putamen, and the nucleus caudatus are structurally affected in children with ADHD. These changes and alterations in limbic regions like ACC and amygdala are more pronounced in non-treated populations and seem to diminish over time from child to adulthood. Treatment seems to have positive effects on brain structure.
Several other studies,[97-101] including a meta-analytic review[98] and a retrospective study,[97] suggested that stimulant therapy in childhood is associated with a reduced risk of subsequent substance use, cigarette smoking and alcohol use disorders. ... Recent studies have demonstrated that stimulants, along with the non-stimulants atomoxetine and extended-release guanfacine, are continuously effective for more than 2-year treatment periods with few and tolerable adverse effects. The effectiveness of long-term therapy includes not only the core symptoms of ADHD, but also improved quality of life and academic achievements. The most concerning short-term adverse effects of stimulants, such as elevated blood pressure and heart rate, waned in long-term follow-up studies. ... The current data do not support the potential impact of stimulants on the worsening or development of tics or substance abuse into adulthood. In the longest follow-up study (of more than 10 years), lifetime stimulant treatment for ADHD was effective and protective against the development of adverse psychiatric disorders.
The highest proportion of improved outcomes was reported with combination treatment (83% of outcomes). Among significantly improved outcomes, the largest effect sizes were found for combination treatment. The greatest improvements were associated with academic, self-esteem, or social function outcomes.
The main efficacy-related conclusions of this review are: (a) medications demonstrated the strongest and most consistent effects on core ADHD symptoms (especially inattention), (b) heterogeneous C/BTs demonstrated inconsistent effects on ADHD symptoms, strong consistent effects on impairment and executive function skills, and modest consistent effects on internalizing symptoms and analogue note-taking performance, (c) C/BTs demonstrated consistent maintenance effects for executive function skills and impairment up to 6 months and possibly 3 years post-treatment, (d) though comparing the efficacy of two C/BTs rarely led to significant differences, which C/BT worked best for whom could be reliably predicted from patient- and provider-level moderators ...
Thus, maximal therapeutic benefit (in terms of breadth of response and maintenance of effects) might be achieved by combining medication and C/BTs, a recommendation generally reflected in current practice parameters (AACAP, 2007; AADPA, 2022; NICE, 2018; Wolraich et al., 2019).
We conducted the first systematic review and meta-analysis investigating the effects of medication for ADHD on quality of life (QoL) in parallel or crossover RCTs. Overall, we found that methylphenidate, amphetamines, and atomoxetine were significantly more efficacious than placebo in improving QoL in people with ADHD. ...
Four studies on amphetamines (950 participants with ADHD in total; 45% adults) reported relevant data for effect sizes to be computed. The meta-analysis on 14 effect sizes showed that amphetamines led to better QoL than placebo in individuals with ADHD.
Our findings were based on 113 RCTs, including 14 887 participants, and indicated that stimulants were the only intervention that was supported by evidence of efficacy in the short term (ie, at timepoints closest to 12 weeks) for core symptoms of ADHD in adults (both self-reported and clinician-reported) and was associated with good acceptability (all-cause discontinuation).
Only one paper53 examining outcomes beyond 36 months met the review criteria. ... There is high level evidence suggesting that pharmacological treatment can have a major beneficial effect on the core symptoms of ADHD (hyperactivity, inattention, and impulsivity) in approximately 80% of cases compared with placebo controls, in the short term.
BED subjects have substantial decrements in their ventral striatal reward pathways and diminished ability to recruit fronto-cortical impulse-control circuits to implement dietary restraint. ...
There is not only substantial overlap between the psychopathology of BED and ADHD but also a clear association between these two disorders. Lisdexamfetamine's ability to reduce impulsivity and increase cognitive control in ADHD supports the hypothesis that efficacy in BED is dependent on treating its core obsessive, compulsive and impulsive behaviours.
Genetic polymorphisms associated with abnormal dopaminergic signaling have been found in individuals who exhibit binge-eating behavior, and the binge-eating episodes,which often involve the consumption of highly palatable food, further stimulate the dopaminergic system. This ongoing stimulation may contribute to progressive impairments in dopamine signaling. Lisdexamfetamine is hypothesized to reduce binge-eating behavior by normalizing dopaminergic activity. ...
After 12 weeks, both studies found significant reductions in the number of binge-eating days per week in the active treatment group compared with placebo (P < .001 for both studies; Figure 1). Lisdexamfetamine was also found to be superior to placebo on a number of secondary outcome measures including global improvement, binge-eating cessation for 4 weeks, and reduction of obsessive-compulsive binge-eating symptoms, body weight, and triglycerides.
LDX is commonly used in the treatment of ADHD, and is the only treatment for BED that is approved by the Food and Drug Administration (FDA) and the Therapeutic Goods Administration (TGA). LDX, like all amphetamine stimulants, has direct appetite suppressant effects that may be therapeutically useful in BED, although long-term neuroadaptations in dopaminergic and noradrenergic systems caused by LDX may also be relevant, leading to improved regulation of eating behaviours, attentional processes and goal-directed behaviours. ...
Evidently, there is a substantial volume of trials with high-quality evidence supporting the efficacy of LDX in reducing binge eating frequency in treatment of adults with moderate to severe BED at 50–70 mg/day.
Stimulant medications may be especially effective for individuals with BED because of dual effects on reward and executive function systems. Indeed, the only FDA-approved pharmacotherapy for BED is LDX, a d-amphetamine prodrug. ...
In humans, RCTs found that LDX reduced binge eating and impulsivity/compulsivity symptoms. Notably, there is a strong correlation between compulsivity symptoms and severity/frequency of binge eating episodes observed in LDX trials. Further, in individuals with BED, changes in prefrontal brain systems associated with LDX treatment were related to treatment outcome.
Our meta-analysis of the four RCT data sets (Guerdjikova et al., 2016; McElroy et al., 2015b; McElroy et al., 2016a) showed an overall significant effect of LDX on binge-eating symptom change. ...
BED has been described as an impulse control disorder since one of the key symptoms of the disorder is a lack of control over eating (American Psychiatric Association, 2013) and it is possible that LDX may be effective in treating BED at least in part by reducing impulsivity, compulsivity, and the repetitive nature of binge eating. There is extensive evidence that loss of impulse control in BED is a causal factor in provoking bingeing symptoms (Colles et al., 2008; Galanti et al., 2007; Giel et al., 2017; McElroy et al., 2016a; Nasser et al., 2004; Schag et al., 2013). More specifically, BED is associated with motor impulsivity and non-planning impulsivity which could initiate and maintain binge eating (Nasser et al., 2004). Neuroimaging studies using the Stroop task to measure impulse control have shown that BED patients have decreased BOLD fMRI activity in brain areas involved in self-regulation and impulse control including VMPFC, inferior frontal gyrus (IFG), and insula during performance of the task compared to lean and obese controls (Balodis et al., 2013b). ...
It is conceivable that in BED patients a low 30 mg dose of LDX could reduce food intake by suppressing appetite or enhancing satiety and higher (50 and 70 mg) doses of the drug may have a dual suppressant effect on food intake and binge-eating frequency.
Peripheral norepinephrine concentration rises as well. As demonstrated after Dextroamphetamine administration, plasma norepinephrine can rise up to 400 pg/mL, a level comparable to that achieved during mild physical activity. Cumulative effect on norepinephrine concentration is likely when amphetamine-type medications are given in the setting of acute illness or combined with activities leading to catecholamine release, such as exercise. ... The primary effect of norepinephrine on ketogenesis is mediated through increased substrate availability. As shown by Krentz et al., at high physiological concentrations, norepinephrine induces accelerated lipolysis and increases NEFA formation significantly. Secondly, norepinephrine stimulates ketogenesis directly at the hepatocyte level. As reported by Keller et al., norepinephrine infusion increased ketone bodies concentration to a greater degree when compared to NEFA concentration (155 ± 30 versus 57 ± 16%), suggesting direct hepatic ketogenic effect.
An 11-week, double-blind RCT examined the effects of three doses of lisdexamfetamine (30 mg/day, 50 mg/day, 70 mg/day) and placebo on binge eating frequency. Results indicated that 50 mg and 70 mg doses were superior to placebo in reducing binge eating. Two follow-up 12-week RCTs confirmed the superiority of 50 and 70 mg doses to placebo in improving binge eating and secondary outcome measures, including obsessive–compulsive symptoms, body weight, and global improvement. ... Subsequent studies of lisdexamfetamine provided further support for the medication's safety and efficacy and provided additional evidence that continued use may be better than placebo in preventing relapse. While it is considered safe and effective, lisdexamfetamine's side effect profile and risk for misuse may make it inappropriate for certain patients.
Narcolepsy type 1 was called "narcolepsy with cataplexy" before 2014 (AASM, 2005), but was renamed NT1 in the third and last international classification of sleep disorders (AASM, 2014). ... A low level of Hcrt-1 in the CSF is very sensitive and specific for the diagnosis of NT1. ...
All patients with low CSF Hcrt-1 levels are considered as NT1 patients, even if they report no cataplexy (in about 10–20% of cases), and all patients with normal CSF Hcrt-1 levels (or without cataplexy when the lumbar puncture is not performed) as NT2 patients (Baumann et al., 2014). ...
In patients with NT1, the absence of Hcrt leads to the inhibition of regions that suppress REM sleep, thus allowing the activation of descending pathways inhibiting motoneurons, leading to cataplexy.
At the pathophysiological level, it is now clear that most narcolepsy cases with cataplexy, and a minority of cases (5–30 %) without cataplexy or with atypical cataplexy-like symptoms, are caused by a lack of hypocretin (orexin) of likely an autoimmune origin. In these cases, once the disease is established, the majority of the 70,000 hypocretin-producing cells have been destroyed, and the disorder is irreversible. ...
Amphetamines are exceptionally wake-promoting, and at high doses also reduce cataplexy in narcoleptic patients, an effect best explained by its action on adrenergic and serotoninergic synapses. ...
The D-isomer is more specific for DA transmission and is a better stimulant compound. Some effects on cataplexy (especially for the L-isomer), secondary to adrenergic effects, occur at higher doses. ...
Numerous studies have shown that increased dopamine release is the main property explaining wake-promotion, although norepinephrine effects also contribute.
Alertness and associated forebrain and cortical arousal are mediated by several ascending pathways with distinct neuronal components that project from the upper brain stem near the junction of the pons and the midbrain. ...
Key cell populations of the ascending arousal pathway include cholinergic, noradrenergic, serotoninergic, dopaminergic, and histaminergic neurons located in the pedunculopontine and laterodorsal tegmental nucleus (PPT/LDT), locus coeruleus, dorsal and median raphe nucleus, and tuberomammillary nucleus (TMN), respectively. ...
The mechanism of action of sympathomimetic alerting drugs (eg, dextro- and methamphetamine, methylphenidate) is direct or indirect stimulation of dopaminergic and noradrenergic nuclei, which in turn heightens the efficacy of the ventral periaqueductal grey area and locus coeruleus, both components of the secondary branch of the ascending arousal system. ...
Sympathomimetic drugs have long been used to treat narcolepsy
The TF identified 1 double-blind RCT, 1 single-blind RCT, and 1 retrospective observational long-term self-reported case series assessing the efficacy of dextroamphetamine in patients with narcolepsy type 1 and narcolepsy type 2. These studies demonstrated clinically significant improvements in excessive daytime sleepiness and cataplexy.
The usefulness of amphetamines is limited by a potential risk of abuse, and their cardiovascular adverse effects (Table 1). That is why, even though they are cheaper than other drugs, and efficient, they remain third-line therapy in narcolepsy. Three class II studies showed an improvement of EDS in that disease. ...
Despite the potential for drug abuse or tolerance using stimulants, patients with narcolepsy rarely exhibit addiction to their medication. ...
Some stimulants, such as mazindol, amphetamines, and pitolisant, may also have some anticataplectic effects.
Recent clinical trials and practice guidelines have confirmed that stimulants such as modafinil, armodafinil, or sodium oxybate (as first line); methylphenidate and pitolisant (as second line [pitolisant is currently only available in Europe]); and amphetamines (as third line) are appropriate medications for excessive daytime sleepiness.
The first agents used to treat EDS (ie, amphetamines, methylphenidate) are now considered second- or third-line options because newer medications have been developed with improved tolerability and lower abuse potential (eg, modafinil/armodafinil, solriamfetol, pitolisant)
The procognitive actions of psychostimulants are only associated with low doses. Surprisingly, despite nearly 80 years of clinical use, the neurobiology of the procognitive actions of psychostimulants has only recently been systematically investigated. Findings from this research unambiguously demonstrate that the cognition-enhancing effects of psychostimulants involve the preferential elevation of catecholamines in the PFC and the subsequent activation of norepinephrine α2 and dopamine D1 receptors. ... This differential modulation of PFC-dependent processes across dose appears to be associated with the differential involvement of noradrenergic α2 versus α1 receptors. Collectively, this evidence indicates that at low, clinically relevant doses, psychostimulants are devoid of the behavioral and neurochemical actions that define this class of drugs and instead act largely as cognitive enhancers (improving PFC-dependent function). ... In particular, in both animals and humans, lower doses maximally improve performance in tests of working memory and response inhibition, whereas maximal suppression of overt behavior and facilitation of attentional processes occurs at higher doses.
Specifically, in a set of experiments limited to high-quality designs, we found significant enhancement of several cognitive abilities. ... The results of this meta-analysis ... do confirm the reality of cognitive enhancing effects for normal healthy adults in general, while also indicating that these effects are modest in size.
Amphetamine has been shown to improve consolidation of information (0.02 ≥ P ≤ 0.05), leading to improved recall.
misuse of prescription stimulants has become a serious problem on college campuses across the US and has been recently documented in other countries as well. ... Indeed, large numbers of students claim to have engaged in the nonmedical use of prescription stimulants, which is reflected in lifetime prevalence rates of prescription stimulant misuse ranging from 5% to nearly 34% of students.
Overall, the data suggest that ADHD medication misuse and diversion are common health care problems for stimulant medications, with the prevalence believed to be approximately 5% to 10% of high school students and 5% to 35% of college students, depending on the study.
Amphetamines and caffeine are stimulants that increase alertness, improve focus, decrease reaction time, and delay fatigue, allowing for an increased intensity and duration of training ...
Physiologic and performance effects
• Amphetamines increase dopamine/norepinephrine release and inhibit their reuptake, leading to central nervous system (CNS) stimulation
• Amphetamines seem to enhance athletic performance in anaerobic conditions 39 40
• Improved reaction time
• Increased muscle strength and delayed muscle fatigue
• Increased acceleration
• Increased alertness and attention to task
In 1980, Chandler and Blair47 showed significant increases in knee extension strength, acceleration, anaerobic capacity, time to exhaustion during exercise, pre-exercise and maximum heart rates, and time to exhaustion during maximal oxygen consumption (VO2 max) testing after administration of 15 mg of dextroamphetamine versus placebo. Most of the information to answer this question has been obtained in the past decade through studies of fatigue rather than an attempt to systematically investigate the effect of ADHD drugs on exercise.
In high-ambient temperatures, dopaminergic manipulations clearly improve performance. The distribution of the power output reveals that after dopamine reuptake inhibition, subjects are able to maintain a higher power output compared with placebo. ... Dopaminergic drugs appear to override a safety switch and allow athletes to use a reserve capacity that is 'off-limits' in a normal (placebo) situation.
Manipulations of dopaminergic signaling profoundly influence interval timing, leading to the hypothesis that dopamine influences internal pacemaker, or "clock," activity. For instance, amphetamine, which increases concentrations of dopamine at the synaptic cleft advances the start of responding during interval timing, whereas antagonists of D2 type dopamine receptors typically slow timing;... Depletion of dopamine in healthy volunteers impairs timing, while amphetamine releases synaptic dopamine and speeds up timing.
Aside from accounting for the reduced performance of mentally fatigued participants, this model rationalizes the reduced RPE and hence improved cycling time trial performance of athletes using a glucose mouthwash (Chambers et al., 2009) and the greater power output during a RPE matched cycling time trial following amphetamine ingestion (Swart, 2009). ... Dopamine stimulating drugs are known to enhance aspects of exercise performance (Roelands et al., 2008)
This indicates that subjects did not feel they were producing more power and consequently more heat. The authors concluded that the "safety switch" or the mechanisms existing in the body to prevent harmful effects are overridden by the drug administration (Roelands et al., 2008b). Taken together, these data indicate strong ergogenic effects of an increased DA concentration in the brain, without any change in the perception of effort.
Inactive lisdexamfetamine is completely (>98%) converted to its active metabolite D-amphetamine in the circulation (Pennick, 2010; Sharman and Pennick, 2014). When lisdexamfetamine is misused intranasally or intravenously, the pharmacokinetics are similar to oral use (Jasinski and Krishnan, 2009b; Ermer et al., 2011), and the subjective effects are not enhanced by parenteral administration in contrast to D-amphetamine (Lile et al., 2011) thus reducing the risk of parenteral misuse of lisdexamfetamine compared with D-amphetamine. Intravenous lisdexamfetamine use also produced significantly lower increases in "drug liking" and "stimulant effects" compared with D-amphetamine in intravenous substance users (Jasinski and Krishnan, 2009a).
VMAT2 is the CNS vesicular transporter for not only the biogenic amines DA, NE, EPI, 5-HT, and HIS, but likely also for the trace amines TYR, PEA, and thyronamine (THYR) ... [Trace aminergic] neurons in mammalian CNS would be identifiable as neurons expressing VMAT2 for storage, and the biosynthetic enzyme aromatic amino acid decarboxylase (AADC).
Despite the challenges in determining synaptic vesicle pH, the proton gradient across the vesicle membrane is of fundamental importance for its function. Exposure of isolated catecholamine vesicles to protonophores collapses the pH gradient and rapidly redistributes transmitter from inside to outside the vesicle. ... Amphetamine and its derivatives like methamphetamine are weak base compounds that are the only widely used class of drugs known to elicit transmitter release by a non-exocytic mechanism. As substrates for both DAT and VMAT, amphetamines can be taken up to the cytosol and then sequestered in vesicles, where they act to collapse the vesicular pH gradient.
Three important new aspects of TAs action have recently emerged: (a) inhibition of firing due to increased release of dopamine; (b) reduction of D2 and GABAB receptor-mediated inhibitory responses (excitatory effects due to disinhibition); and (c) a direct TA1 receptor-mediated activation of GIRK channels which produce cell membrane hyperpolarization.
AMPH also increases intracellular calcium (Gnegy et al., 2004) that is associated with calmodulin/CamKII activation (Wei et al., 2007) and modulation and trafficking of the DAT (Fog et al., 2006; Sakrikar et al., 2012). ... For example, AMPH increases extracellular glutamate in various brain regions including the striatum, VTA and NAc (Del Arco et al., 1999; Kim et al., 1981; Mora and Porras, 1993; Xue et al., 1996), but it has not been established whether this change can be explained by increased synaptic release or by reduced clearance of glutamate. ... DHK-sensitive, EAAT2 uptake was not altered by AMPH (Figure 1A). The remaining glutamate transport in these midbrain cultures is likely mediated by EAAT3 and this component was significantly decreased by AMPH
AMPH and METH also stimulate DA efflux, which is thought to be a crucial element in their addictive properties [80], although the mechanisms do not appear to be identical for each drug [81]. These processes are PKCβ– and CaMK–dependent [72, 82], and PKCβ knock-out mice display decreased AMPH-induced efflux that correlates with reduced AMPH-induced locomotion [72].
Dopamine-β-hydroxylase catalyzed the removal of the pro-R hydrogen atom and the production of 1-norephedrine, (2S,1R)-2-amino-1-hydroxyl-1-phenylpropane, from d-amphetamine.
Hydroxyamphetamine was administered orally to five human subjects ... Since conversion of hydroxyamphetamine to hydroxynorephedrine occurs in vitro by the action of dopamine-β-oxidase, a simple method is suggested for measuring the activity of this enzyme and the effect of its inhibitors in man. ... The lack of effect of administration of neomycin to one patient indicates that the hydroxylation occurs in body tissues. ... a major portion of the β-hydroxylation of hydroxyamphetamine occurs in non-adrenal tissue. Unfortunately, at the present time one cannot be completely certain that the hydroxylation of hydroxyamphetamine in vivo is accomplished by the same enzyme which converts dopamine to noradrenaline.
Figure 1. Glycine conjugation of benzoic acid. The glycine conjugation pathway consists of two steps. First benzoate is ligated to CoASH to form the high-energy benzoyl-CoA thioester. This reaction is catalyzed by the HXM-A and HXM-B medium-chain acid:CoA ligases and requires energy in the form of ATP. ... The benzoyl-CoA is then conjugated to glycine by GLYAT to form hippuric acid, releasing CoASH. In addition to the factors listed in the boxes, the levels of ATP, CoASH, and glycine may influence the overall rate of the glycine conjugation pathway.
The biologic significance of the different levels of serum DβH activity was studied in two ways. First, in vivo ability to β-hydroxylate the synthetic substrate hydroxyamphetamine was compared in two subjects with low serum DβH activity and two subjects with average activity. ... In one study, hydroxyamphetamine (Paredrine), a synthetic substrate for DβH, was administered to subjects with either low or average levels of serum DβH activity. The percent of the drug hydroxylated to hydroxynorephedrine was comparable in all subjects (6.5-9.62) (Table 3).
In species where aromatic hydroxylation of amphetamine is the major metabolic pathway, p-hydroxyamphetamine (POH) and p-hydroxynorephedrine (PHN) may contribute to the pharmacological profile of the parent drug. ... The location of the p-hydroxylation and β-hydroxylation reactions is important in species where aromatic hydroxylation of amphetamine is the predominant pathway of metabolism. Following systemic administration of amphetamine to rats, POH has been found in urine and in plasma.
The observed lack of a significant accumulation of PHN in brain following the intraventricular administration of (+)-amphetamine and the formation of appreciable amounts of PHN from (+)-POH in brain tissue in vivo supports the view that the aromatic hydroxylation of amphetamine following its systemic administration occurs predominantly in the periphery, and that POH is then transported through the blood-brain barrier, taken up by noradrenergic neurones in brain where (+)-POH is converted in the storage vesicles by dopamine β-hydroxylase to PHN.
The metabolism of p-OHA to p-OHNor is well documented and dopamine-β hydroxylase present in noradrenergic neurons could easily convert p-OHA to p-OHNor after intraventricular administration.
The highest proportion of improved outcomes was reported with combination treatment (83% of outcomes). Among significantly improved outcomes, the largest effect sizes were found for combination treatment. The greatest improvements were associated with academic, self-esteem, or social function outcomes.
Only one paper53 examining outcomes beyond 36 months met the review criteria. ... There is high level evidence suggesting that pharmacological treatment can have a major beneficial effect on the core symptoms of ADHD (hyperactivity, inattention, and impulsivity) in approximately 80% of cases compared with placebo controls, in the short term.
BED subjects have substantial decrements in their ventral striatal reward pathways and diminished ability to recruit fronto-cortical impulse-control circuits to implement dietary restraint. ...
There is not only substantial overlap between the psychopathology of BED and ADHD but also a clear association between these two disorders. Lisdexamfetamine's ability to reduce impulsivity and increase cognitive control in ADHD supports the hypothesis that efficacy in BED is dependent on treating its core obsessive, compulsive and impulsive behaviours.
LDX is commonly used in the treatment of ADHD, and is the only treatment for BED that is approved by the Food and Drug Administration (FDA) and the Therapeutic Goods Administration (TGA). LDX, like all amphetamine stimulants, has direct appetite suppressant effects that may be therapeutically useful in BED, although long-term neuroadaptations in dopaminergic and noradrenergic systems caused by LDX may also be relevant, leading to improved regulation of eating behaviours, attentional processes and goal-directed behaviours. ...
Evidently, there is a substantial volume of trials with high-quality evidence supporting the efficacy of LDX in reducing binge eating frequency in treatment of adults with moderate to severe BED at 50–70 mg/day.
Stimulant medications may be especially effective for individuals with BED because of dual effects on reward and executive function systems. Indeed, the only FDA-approved pharmacotherapy for BED is LDX, a d-amphetamine prodrug. ...
In humans, RCTs found that LDX reduced binge eating and impulsivity/compulsivity symptoms. Notably, there is a strong correlation between compulsivity symptoms and severity/frequency of binge eating episodes observed in LDX trials. Further, in individuals with BED, changes in prefrontal brain systems associated with LDX treatment were related to treatment outcome.
Peripheral norepinephrine concentration rises as well. As demonstrated after Dextroamphetamine administration, plasma norepinephrine can rise up to 400 pg/mL, a level comparable to that achieved during mild physical activity. Cumulative effect on norepinephrine concentration is likely when amphetamine-type medications are given in the setting of acute illness or combined with activities leading to catecholamine release, such as exercise. ... The primary effect of norepinephrine on ketogenesis is mediated through increased substrate availability. As shown by Krentz et al., at high physiological concentrations, norepinephrine induces accelerated lipolysis and increases NEFA formation significantly. Secondly, norepinephrine stimulates ketogenesis directly at the hepatocyte level. As reported by Keller et al., norepinephrine infusion increased ketone bodies concentration to a greater degree when compared to NEFA concentration (155 ± 30 versus 57 ± 16%), suggesting direct hepatic ketogenic effect.
An 11-week, double-blind RCT examined the effects of three doses of lisdexamfetamine (30 mg/day, 50 mg/day, 70 mg/day) and placebo on binge eating frequency. Results indicated that 50 mg and 70 mg doses were superior to placebo in reducing binge eating. Two follow-up 12-week RCTs confirmed the superiority of 50 and 70 mg doses to placebo in improving binge eating and secondary outcome measures, including obsessive–compulsive symptoms, body weight, and global improvement. ... Subsequent studies of lisdexamfetamine provided further support for the medication's safety and efficacy and provided additional evidence that continued use may be better than placebo in preventing relapse. While it is considered safe and effective, lisdexamfetamine's side effect profile and risk for misuse may make it inappropriate for certain patients.
At the pathophysiological level, it is now clear that most narcolepsy cases with cataplexy, and a minority of cases (5–30 %) without cataplexy or with atypical cataplexy-like symptoms, are caused by a lack of hypocretin (orexin) of likely an autoimmune origin. In these cases, once the disease is established, the majority of the 70,000 hypocretin-producing cells have been destroyed, and the disorder is irreversible. ...
Amphetamines are exceptionally wake-promoting, and at high doses also reduce cataplexy in narcoleptic patients, an effect best explained by its action on adrenergic and serotoninergic synapses. ...
The D-isomer is more specific for DA transmission and is a better stimulant compound. Some effects on cataplexy (especially for the L-isomer), secondary to adrenergic effects, occur at higher doses. ...
Numerous studies have shown that increased dopamine release is the main property explaining wake-promotion, although norepinephrine effects also contribute.
Alertness and associated forebrain and cortical arousal are mediated by several ascending pathways with distinct neuronal components that project from the upper brain stem near the junction of the pons and the midbrain. ...
Key cell populations of the ascending arousal pathway include cholinergic, noradrenergic, serotoninergic, dopaminergic, and histaminergic neurons located in the pedunculopontine and laterodorsal tegmental nucleus (PPT/LDT), locus coeruleus, dorsal and median raphe nucleus, and tuberomammillary nucleus (TMN), respectively. ...
The mechanism of action of sympathomimetic alerting drugs (eg, dextro- and methamphetamine, methylphenidate) is direct or indirect stimulation of dopaminergic and noradrenergic nuclei, which in turn heightens the efficacy of the ventral periaqueductal grey area and locus coeruleus, both components of the secondary branch of the ascending arousal system. ...
Sympathomimetic drugs have long been used to treat narcolepsy
The TF identified 1 double-blind RCT, 1 single-blind RCT, and 1 retrospective observational long-term self-reported case series assessing the efficacy of dextroamphetamine in patients with narcolepsy type 1 and narcolepsy type 2. These studies demonstrated clinically significant improvements in excessive daytime sleepiness and cataplexy.
The procognitive actions of psychostimulants are only associated with low doses. Surprisingly, despite nearly 80 years of clinical use, the neurobiology of the procognitive actions of psychostimulants has only recently been systematically investigated. Findings from this research unambiguously demonstrate that the cognition-enhancing effects of psychostimulants involve the preferential elevation of catecholamines in the PFC and the subsequent activation of norepinephrine α2 and dopamine D1 receptors. ... This differential modulation of PFC-dependent processes across dose appears to be associated with the differential involvement of noradrenergic α2 versus α1 receptors. Collectively, this evidence indicates that at low, clinically relevant doses, psychostimulants are devoid of the behavioral and neurochemical actions that define this class of drugs and instead act largely as cognitive enhancers (improving PFC-dependent function). ... In particular, in both animals and humans, lower doses maximally improve performance in tests of working memory and response inhibition, whereas maximal suppression of overt behavior and facilitation of attentional processes occurs at higher doses.
Amphetamine has been shown to improve consolidation of information (0.02 ≥ P ≤ 0.05), leading to improved recall.
misuse of prescription stimulants has become a serious problem on college campuses across the US and has been recently documented in other countries as well. ... Indeed, large numbers of students claim to have engaged in the nonmedical use of prescription stimulants, which is reflected in lifetime prevalence rates of prescription stimulant misuse ranging from 5% to nearly 34% of students.
Manipulations of dopaminergic signaling profoundly influence interval timing, leading to the hypothesis that dopamine influences internal pacemaker, or "clock," activity. For instance, amphetamine, which increases concentrations of dopamine at the synaptic cleft advances the start of responding during interval timing, whereas antagonists of D2 type dopamine receptors typically slow timing;... Depletion of dopamine in healthy volunteers impairs timing, while amphetamine releases synaptic dopamine and speeds up timing.
Aside from accounting for the reduced performance of mentally fatigued participants, this model rationalizes the reduced RPE and hence improved cycling time trial performance of athletes using a glucose mouthwash (Chambers et al., 2009) and the greater power output during a RPE matched cycling time trial following amphetamine ingestion (Swart, 2009). ... Dopamine stimulating drugs are known to enhance aspects of exercise performance (Roelands et al., 2008)
Inactive lisdexamfetamine is completely (>98%) converted to its active metabolite D-amphetamine in the circulation (Pennick, 2010; Sharman and Pennick, 2014). When lisdexamfetamine is misused intranasally or intravenously, the pharmacokinetics are similar to oral use (Jasinski and Krishnan, 2009b; Ermer et al., 2011), and the subjective effects are not enhanced by parenteral administration in contrast to D-amphetamine (Lile et al., 2011) thus reducing the risk of parenteral misuse of lisdexamfetamine compared with D-amphetamine. Intravenous lisdexamfetamine use also produced significantly lower increases in "drug liking" and "stimulant effects" compared with D-amphetamine in intravenous substance users (Jasinski and Krishnan, 2009a).
VMAT2 is the CNS vesicular transporter for not only the biogenic amines DA, NE, EPI, 5-HT, and HIS, but likely also for the trace amines TYR, PEA, and thyronamine (THYR) ... [Trace aminergic] neurons in mammalian CNS would be identifiable as neurons expressing VMAT2 for storage, and the biosynthetic enzyme aromatic amino acid decarboxylase (AADC).
Despite the challenges in determining synaptic vesicle pH, the proton gradient across the vesicle membrane is of fundamental importance for its function. Exposure of isolated catecholamine vesicles to protonophores collapses the pH gradient and rapidly redistributes transmitter from inside to outside the vesicle. ... Amphetamine and its derivatives like methamphetamine are weak base compounds that are the only widely used class of drugs known to elicit transmitter release by a non-exocytic mechanism. As substrates for both DAT and VMAT, amphetamines can be taken up to the cytosol and then sequestered in vesicles, where they act to collapse the vesicular pH gradient.
Three important new aspects of TAs action have recently emerged: (a) inhibition of firing due to increased release of dopamine; (b) reduction of D2 and GABAB receptor-mediated inhibitory responses (excitatory effects due to disinhibition); and (c) a direct TA1 receptor-mediated activation of GIRK channels which produce cell membrane hyperpolarization.
AMPH also increases intracellular calcium (Gnegy et al., 2004) that is associated with calmodulin/CamKII activation (Wei et al., 2007) and modulation and trafficking of the DAT (Fog et al., 2006; Sakrikar et al., 2012). ... For example, AMPH increases extracellular glutamate in various brain regions including the striatum, VTA and NAc (Del Arco et al., 1999; Kim et al., 1981; Mora and Porras, 1993; Xue et al., 1996), but it has not been established whether this change can be explained by increased synaptic release or by reduced clearance of glutamate. ... DHK-sensitive, EAAT2 uptake was not altered by AMPH (Figure 1A). The remaining glutamate transport in these midbrain cultures is likely mediated by EAAT3 and this component was significantly decreased by AMPH
AMPH and METH also stimulate DA efflux, which is thought to be a crucial element in their addictive properties [80], although the mechanisms do not appear to be identical for each drug [81]. These processes are PKCβ– and CaMK–dependent [72, 82], and PKCβ knock-out mice display decreased AMPH-induced efflux that correlates with reduced AMPH-induced locomotion [72].
Hydroxyamphetamine was administered orally to five human subjects ... Since conversion of hydroxyamphetamine to hydroxynorephedrine occurs in vitro by the action of dopamine-β-oxidase, a simple method is suggested for measuring the activity of this enzyme and the effect of its inhibitors in man. ... The lack of effect of administration of neomycin to one patient indicates that the hydroxylation occurs in body tissues. ... a major portion of the β-hydroxylation of hydroxyamphetamine occurs in non-adrenal tissue. Unfortunately, at the present time one cannot be completely certain that the hydroxylation of hydroxyamphetamine in vivo is accomplished by the same enzyme which converts dopamine to noradrenaline.
Duration of effect varies depending on agent and urine pH. Excretion is enhanced in more acidic urine. Half-life is 7 to 34 hours and is, in part, dependent on urine pH (half-life is longer with alkaline urine). ... Amphetamines are distributed into most body tissues with high concentrations occurring in the brain and CSF. Amphetamine appears in the urine within about 3 hours following oral administration. ... Three days after a dose of (+ or -)-amphetamine, human subjects had excreted 91% of the (14)C in the urine
The procognitive actions of psychostimulants are only associated with low doses. Surprisingly, despite nearly 80 years of clinical use, the neurobiology of the procognitive actions of psychostimulants has only recently been systematically investigated. Findings from this research unambiguously demonstrate that the cognition-enhancing effects of psychostimulants involve the preferential elevation of catecholamines in the PFC and the subsequent activation of norepinephrine α2 and dopamine D1 receptors. ... This differential modulation of PFC-dependent processes across dose appears to be associated with the differential involvement of noradrenergic α2 versus α1 receptors. Collectively, this evidence indicates that at low, clinically relevant doses, psychostimulants are devoid of the behavioral and neurochemical actions that define this class of drugs and instead act largely as cognitive enhancers (improving PFC-dependent function). ... In particular, in both animals and humans, lower doses maximally improve performance in tests of working memory and response inhibition, whereas maximal suppression of overt behavior and facilitation of attentional processes occurs at higher doses.
Onset of efficacy was earliest for d-MPH-ER at 0.5 hours, followed by d, l-MPH-LA at 1 to 2 hours, MCD at 1.5 hours, d, l-MPH-OR at 1 to 2 hours, MAS-XR at 1.5 to 2 hours, MTS at 2 hours, and LDX at approximately 2 hours. ... MAS-XR, and LDX have a long duration of action at 12 hours postdose
Basal ganglia regions like the right globus pallidus, the right putamen, and the nucleus caudatus are structurally affected in children with ADHD. These changes and alterations in limbic regions like ACC and amygdala are more pronounced in non-treated populations and seem to diminish over time from child to adulthood. Treatment seems to have positive effects on brain structure.
Several other studies,[97-101] including a meta-analytic review[98] and a retrospective study,[97] suggested that stimulant therapy in childhood is associated with a reduced risk of subsequent substance use, cigarette smoking and alcohol use disorders. ... Recent studies have demonstrated that stimulants, along with the non-stimulants atomoxetine and extended-release guanfacine, are continuously effective for more than 2-year treatment periods with few and tolerable adverse effects. The effectiveness of long-term therapy includes not only the core symptoms of ADHD, but also improved quality of life and academic achievements. The most concerning short-term adverse effects of stimulants, such as elevated blood pressure and heart rate, waned in long-term follow-up studies. ... The current data do not support the potential impact of stimulants on the worsening or development of tics or substance abuse into adulthood. In the longest follow-up study (of more than 10 years), lifetime stimulant treatment for ADHD was effective and protective against the development of adverse psychiatric disorders.
Specifically, in a set of experiments limited to high-quality designs, we found significant enhancement of several cognitive abilities. ... The results of this meta-analysis ... do confirm the reality of cognitive enhancing effects for normal healthy adults in general, while also indicating that these effects are modest in size.
Overall, the data suggest that ADHD medication misuse and diversion are common health care problems for stimulant medications, with the prevalence believed to be approximately 5% to 10% of high school students and 5% to 35% of college students, depending on the study.
In high-ambient temperatures, dopaminergic manipulations clearly improve performance. The distribution of the power output reveals that after dopamine reuptake inhibition, subjects are able to maintain a higher power output compared with placebo. ... Dopaminergic drugs appear to override a safety switch and allow athletes to use a reserve capacity that is 'off-limits' in a normal (placebo) situation.
This indicates that subjects did not feel they were producing more power and consequently more heat. The authors concluded that the "safety switch" or the mechanisms existing in the body to prevent harmful effects are overridden by the drug administration (Roelands et al., 2008b). Taken together, these data indicate strong ergogenic effects of an increased DA concentration in the brain, without any change in the perception of effort.
Figure 1. Glycine conjugation of benzoic acid. The glycine conjugation pathway consists of two steps. First benzoate is ligated to CoASH to form the high-energy benzoyl-CoA thioester. This reaction is catalyzed by the HXM-A and HXM-B medium-chain acid:CoA ligases and requires energy in the form of ATP. ... The benzoyl-CoA is then conjugated to glycine by GLYAT to form hippuric acid, releasing CoASH. In addition to the factors listed in the boxes, the levels of ATP, CoASH, and glycine may influence the overall rate of the glycine conjugation pathway.
The biologic significance of the different levels of serum DβH activity was studied in two ways. First, in vivo ability to β-hydroxylate the synthetic substrate hydroxyamphetamine was compared in two subjects with low serum DβH activity and two subjects with average activity. ... In one study, hydroxyamphetamine (Paredrine), a synthetic substrate for DβH, was administered to subjects with either low or average levels of serum DβH activity. The percent of the drug hydroxylated to hydroxynorephedrine was comparable in all subjects (6.5-9.62) (Table 3).
Clinical development is underway in the US, for mood disorders in children and adolescents for binge eating disorder and ADHD.
• tonically activates inwardly rectifying K(+) channels, which reduces the basal firing frequency of dopamine (DA) neurons of the ventral tegmental area (VTA)
Specifically, in a set of experiments limited to high-quality designs, we found significant enhancement of several cognitive abilities. ... The results of this meta-analysis ... do confirm the reality of cognitive enhancing effects for normal healthy adults in general, while also indicating that these effects are modest in size.
Duration of effect varies depending on agent and urine pH. Excretion is enhanced in more acidic urine. Half-life is 7 to 34 hours and is, in part, dependent on urine pH (half-life is longer with alkaline urine). ... Amphetamines are distributed into most body tissues with high concentrations occurring in the brain and CSF. Amphetamine appears in the urine within about 3 hours following oral administration. ... Three days after a dose of (+ or -)-amphetamine, human subjects had excreted 91% of the (14)C in the urine
