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Mixture of D- and L-amphetamine isomers (racemic mixture)
Mixed sulfates and saccharinates of D-L-amphetamine isomers (Adderall)
Pure D-amphetamine sulphate
Dexamfetamine hemisulfate (Attentin)
D-amphetamine as lisdexamfetamine in lysine-bound form (Vyvanse, Vyvanse, Tyvense)
Racemic methamphetamine sulfate (Desoxyn, USA)
In Germany, amphetamine drugs had to be prepared from raw substances by pharmacists for a long time.2 Since 2011, a D-amphetamine has been available in Germany as a finished drug and approved for the treatment of ADHD (Attentin), and in 2013 a D-amphetamine prodrug was approved for the treatment of children. Lisdexamfetamine contains D-amp in a lysine-bound form (Vyvanse). Since May 2019, Vyvanse Adult has been approved for the treatment of ADHD in adults (30, 50, 70 mg). In 2023, 20, 40, 60 mg were also approved for adults. Since March 2024, Vyvanse and Vyvanse Adult have been combined to form the drug Vyvanse and are available in 20, 30, 40, 50, 60 and 70 mg in Germany.3 Since March 2024, Vyvanse has also been indicated as a first-line treatment for adults according to the Takeda prescribing information, but is still only indicated for children if MPH has been insufficiently effective.4
In Austria, Vyvanse can be prescribed if other medications are ineffective or show side effects. The doctor must justify this to the insurance company.
Amphetamine medication works slightly better in adults than methylphenidate5 and has slightly fewer side effects.
According to the current European consensus, amphetamines are the first choice of medication for ADHD in adults (before methylphenidate) and the second choice of medication in children and adolescents (after methylphenidate).67 While the current text of the S3 guideline from 2017 still states that lisdexamfetamine can only be used in accordance with approval after prior treatment with MPH8, the 2019 S3 guideline is quoted as saying that treatment with psychostimulants is recommended as the first option for adults with ADHD, including the active ingredients methylphenidate and lisdexamfetamine, which are approved for adults.910
Due to the responder/non-responder profile, which differs from MPH, amphetamine medications are particularly suitable for people with ADHD who do not respond to MPH, clearly before the use of non-stimulants (e.g. noradrenergic medications or tricyclic antidepressants).11 A summary of several studies reports a 69% response rate to amphetamine medication and a 59% response rate to methylphenidate. 87 % of people with ADHD responded to one of the two types of drugs.12
Amphetamine medications are also suitable - unlike MPH - for the co-treatment of comorbid dysphoria or depression.1314
According to a Cochrane study, all amphetamine medications work equally well in adults, regardless of the specific form of medication.15 This distinguishes amphetamine medication from methylphenidate, where even a switch to another methylphenidate preparation shows considerable individual differences.
In studies on the effects of amphetamine, it must always be borne in mind that these
AMP usually used in significantly higher doses than for ADHD medication
use immediate release / not prolonged-acting AMP via prodrug
frequently inject AMP, which again results in much faster metabolization
these 3 factors multiply in their effect
There is no doubt that AMP in drug form has a different effect than AMP in drug form.
Noradrenaline release as strong as or stronger than d-AMP
Dextro-AMP (d-AMP)
higher dopamine release than l-AMP
Consequences are that the amphetamine mixed salt preparations available in the USA, which consist of equal parts racemic d,l-AMP sulfate, d,l-AMP aspartate monohydrate and two enantiomerically pure d-AMP salts (d-AMP sulfate and d-AMP saccharate), resulting in a ratio of 3:1 between d-AMP and l-AMP isomers and salts, a relatively greater release of noradrenaline than pure d-AMP, but still a greater release of dopamine than noradrenaline in absolute terms.
The following are relevant for the treatment of ADHD:
Dextroamphetamine is also known as dexamphetamine or dextroamphetamine sulphate.
Dextroamphetamine is the dextrorotatory (D-)enantiomer of amphetamine, as opposed to the levorotatory levoamphetamine (see below).
D-amphetamine drugs have a 3 to 4 times stronger effect on the central nervous system than racemic amphetamine drugs, while at the same time having less sympathomimetic effect in the periphery, which is why D-amphetamine drugs are preferred in ADHD treatment.17
D-amphetamine is only more potent than L-amphetamine with regard to the dopamine transporters, while the effect on noradrenaline transporters is roughly the same.18
This opens up the possibility of emphasizing dopaminergic (dexamphetamine) or balanced dopaminergic and noradrenergic (levoamphetamine) medication.
D-amphetamine is more activating than MPH and is therefore preferably recommended for ADHD-I.19
It is also often more effective than MPH for parallel dysthymia / dysphoria / depression due to the noticeable serotonergic effect20.
1.1.2. Dextroamphetamine from lisdexamfetamine (with lysine binding)¶
Lisdexamfetamine (LDX) is a prodrug of D-amphetamine that is bound to L-lysine to form a substance that is ineffective in itself. Lisdexamfetamine is therefore an active ingredient that is first converted in the body into the actual active substance, in this case D-amphetamine. This means that there is a very low risk of abuse.21 Nevertheless, the effect is dose-dependent and linear up to 250 mg. LDX therefore offers no protection against overdose.22
Lisdexamfetamine (LDX) bound to lysine is rapidly absorbed from the small intestine into the bloodstream. This occurs by active transport, presumably by the peptide transporter 1 [PEPT1]. Enzymatic hydrolysis of the peptide bond to release d-amphetamine into the blood occurs in the lysate and in the cytosolic extract of human erythrocytes, but not in the membrane fraction. This conversion is strongly inhibited by a protease inhibitor cocktail, bestatin and ethylenediaminetetraacetic acid, suggesting an aminopeptidase as the cause of hydrolytic cleavage of the LDX peptide bond. Aminopeptidase B does not appear to be the cause23
Due to the necessary and slow conversion step from LDX to d-AMP, the effect occurs approx. 1 hour later than when taking d-AMP sulphate.22 Unlike LDX, the pharmacologically active d-AMP crosses the blood-brain barrier and enters the CNS, where it exerts its effect.16
Since the effect is quite uniform over the duration of action, the unpleasant rebound effects known from MPH (short-term increased restlessness at the end of the effect) are eliminated or are significantly weaker.
The effect corresponds to D-amphetamine. A conversion table from dexamphetamine to Vyvanse can be found at ADHSpedia.24 Further conversion tables are available from Kühle25and for American preparations from Stutzman et al.26
Trade names:
Vyvanse (EU, since the end of 2013, for children, 20, 30, 40, 50, 60, 70 mg)27
Vyvanse Adult (EU, since 01.05.19, for adults, 30, 50, 70 mg)27. Since 2023, 20, 40 and 60 mg have also been approved in Germany.
Vyvanse and Vyvanse adult were combined in 2023 to form a single medicine with a single approval. It was already an identical product. Since March 2024, Vyvanse has been available in 20, 30, 40, 50, 60 and 70 mg in Germany for children and adults.
Vyvanse (USA) is available in doses of 10 mg to 70 mg28 Lisdexamfetamine is also approved for binge eating in the USA.29
Tyvense (USA) is available in doses from 20 mg to 70 mg
Teva-Lisdexamfetamine (Canada) is available in doses of 10 mg, 20 mg, 30 mg, 40 mg, 50 mg, 60 mg and 70 mg30
Generics:
Since August 2024, lisdexamfetaim has been available in Germany as a generic (Lisdexamfetamine Ratiopharm), with 100-capsule packs also on the market.
Lisdexamfetamine has only been classified as a BtM in Germany since 2013.
Austria appears to be the only country in which Vyvanse is not classified as a narcotic (Austrian term: addictive drug), even as of 2023.31
Due to its long-lasting effect, lisdexamfetamine is subject to steady state formation. Steady state appears to be reached on day 5.32 Consequences of this are that when dosing lisdexamfetamine (Vyvanse), dosage titrations should not be made below a weekly rhythm.
Levoamphetamine (L-amphetamine) is the purely levorotatory isomer of amphetamine.
L-amphetamine is less potent than D-amphetamine in terms of dopamine transporters, while the effect on noradrenaline transporters is roughly the same.18 This makes it slightly more noradrenergic than D-amphetamine, but still predominantly dopaminergic.33
L-amphetamine increases blood pressure and pulse rate more than D-amphetamine34
We are not aware of any ready-to-use L-amphetamine medication approved in Europe. It would have to be produced on individual prescription in pharmacies.
While D,L-amphetamine sulphate mixtures are the most commonly used ADHD medication in the USA, D,L-amphetemine mixtures are only available in a few pharmacies in Germany, which produce them themselves. The production is associated with a waiting time of several weeks. The cost of 180 capsules of 5 mg amphetamine sulphate each was quoted as €200.
Captagon (in Germany until 2003; in Belgium until 2010); no longer available today
2. Amphetamine drugs work differently and in different parts of the brain than methylphenidate¶
Amphetamine drugs have a more complex mechanism of action than methylphenidate.
The description of the effects of amphetamine drugs is contradictory.
It is sometimes argued that amphetamine drugs merely inhibit dopamine reuptake and release dopamine and noradrenaline. More well-founded accounts from the USA (where amphetamine drugs are prescribed more frequently than in Europe and where there is therefore a more intensive debate about them) cite a reuptake inhibition of dopamine and noradrenaline transporters as the effect and no release of dopamine, noradrenaline or serotonin.
In the US, 52.9% of adolescents with ADHD receive MPH and 39.3% receive amphetamine medication as their first prescribed medication. Over the course of treatment, MPH is the primary prescribed medication for around 40% and 33% AMP is the primary prescribed medication.36
In principle, amphetamine drugs are said to have an intraneuronal effect, while methylphenidate and atomoxetine have an extraneuronal effect.37 As amphetamine drugs also address at least the dopamine transporter and the D2 autoreceptor, this is unlikely to be tenable. AMP acts primarily in the striatum and further in the cortex and ventral tegmentum.38
The first computer models now exist that can seriously simulate the effect of ADHD drugs. A computer model for the simulation of type 1 diabetes has already been approved by the FDA as a replacement for preclinical animal studies39
A model comparing MPH and AMP in children and adults with ADHD takes into account the effect on 99 proteins involved in ADHD40
The dopamine increase caused by D-amphetamine in the PFC is much more pronounced and also much more dose-dependent than with MPH, and is therefore easier to control.37 AMP causes:
tonic dopamine firing enhanced by AMP depleting vesicular stores and promoting non-exocytotic release through reverse transport42
phasic dopamine firing: contradictory data
amplified by upregulating vesicular dopamine release42
Stimulants reduce the phasic release of dopamine41
AMP promoted the release of dopamine from vesicles by reducing the affinity of the vesicles for dopamine uptake (from K(m) 0.8 to K(m) 32). However, the amount of dopamine released per pulse was reduced by 82 % (according to another source by 25 to 50 %). The D2 antagonist sulpiride reduced the inhibition of release, i.e. promoted the release. This was reduced in D2-KO mice. In inhibited D2 autoreceptors, AMP increased the extracellular release of dopamine.43
AMP reduces vesicular release4445 (this can affect both tonic and phasic release)
2.1.1.1. Dopamine (re)uptake inhibition via DAT and NET¶
Stimulants (MPH such as AMP inhibit dopamine reuptake46 and thus lead (in low doses) to a 6-fold increase in extracellular dopamine levels.41
The increased extracellular dopamine level acts on presynaptic dopamine D2 autoreceptors at the nerve ending. The D2 autoreceptor activation causes a 2- to 3-fold increase in impulse-associated (phasic) dopamine release. This increase is therefore relatively smaller than the increase in extracellular dopamine. The (relatively smaller) increase in phasic dopamine acts on the postsynaptic D2 dopamine receptors and causes reduced locomotor activity. Higher doses of stimulants increase extracellular dopamine more strongly and result in marked behavioral stimulation that cannot be overcome by phasic activation of inhibitory postsynaptic D2 receptors. High D-Amp doses cause supersaturation of extracellular postsynaptic D1 and D2 receptors, so that they exceed the inhibitory presynaptic effect of low D-AMP doses.41
Amphetamine drugs block the dopamine and noradrenaline transporters in a different way to methylphenidate. While the reuptake inhibition of MPH is similar to that of antidepressants, amphetamine drugs act as a competitive inhibitor and pseudosubstrate on dopamine and noradrenaline transporters and bind to the same site where the monoamines bind to the transporter, thereby also inhibiting NE and DA reuptake.47
Equally as a dopamine and noradrenaline reuptake inhibitor47
“Amphetamines can also stabilize dopamine and noradrenaline transporters in channel configurations, reverse flow through intracellular vesicular monoamine transporters, and cause internalization of dopamine transporters”49
D-AMP drug doses cause a D-AMP plasma concentration of around 150 nM, which is sufficient to occupy a significant proportion of the dopamine transporters. This effect coincides with that of MPH.41
D-amphetamine has approximately three times the affinity for noradrenaline transporters (NET) for reuptake inhibition and two and a half times the affinity for dopamine transporters (DAT) compared to racemic methylphenidate.37
2.1.1.2. Increased release of dopamine (DAT efflux)¶
The increased DAT efflux increases extracellular dopamine.
Amphetamine drugs release dopamine into the extracellular space 374846
Amphetamines therefore not only act as dopamine reuptake inhibitors, but also reverse the DAT function so that the DAT not only does not reabsorb dopamine, but also releases it from the cell (efflux).55
This is newly synthesized dopamine. There is no doubt that this is not a depletion of dopamine reserves, as amphetamine drugs would otherwise have no lasting effect.
It is questionable whether this is dopamine that was previously stored in vesicles. There is no doubt that amphetamine drugs (characteristic of drugs: high dose, rapid application, rapid onset of action) release dopamine. It is questionable whether this is also the case with amphetamine drugs (characteristic: drug-like = low dose, slow release, long-lasting effect), and if so, to what extent this is the case.
(Only) at a very high dosage as a drug, amphetamines also act on the vesicular monoamine transporter 2 (VMAT2) for dopamine and noradrenaline and then trigger an accumulating release of dopamine from the synaptic vesicles. The high amount of dopamine is then swept out into the synaptic cleft by a reversal of action of the dopamine transporters. This mechanism does not take effect at the usual dosage as an ADHD medication.18 In other words: Amphetamines can enter presynaptic monoamine vesicles and cause an efflux of neurotransmitters towards the synapse.56
An administration of 1 mg/kg AMP (injected) already caused a dopamine DAT efflux that was significantly higher at 10 mg/kg.57
AMP increases intracellular Ca2+, which supports phosphorylation of DAT at the N-terminus of the transporter. Phosphorylation (by CaMKII and possibly also by PKCβ) increases probability of DAT efflux from cytoplasmic DA.58
AMP acts on DAT via TAAR1
Amphetamine enables the trace amine-associated receptor 1 (TAAR1) to phosphorylate the DAT transporter. This interrupts the reuptake of dopamine and the DAT is stimulated to release dopamine (efflux).56
AMP also leads to increased intracellular accumulation of DAT59
AMP reduces vesicular release because as a lipophilic weak base and as a substrate for VMAT, AMP promotes the redistribution of dopamine from the synaptic vesicles into the cytosol by collapsing the vesicular pH gradient.44 As a result, AMP reduces the number of dopamine molecules released per vesicle.45
Amphetamine initially reduces VMAT2, while prolonged administration increases it.60MPH increases VMAT2 per se.6162
AMP can inhibit vesicular release by indirectly activating D2 autoreceptors. The activation of D2 autoreceptors regulates potassium channels, which in turn regulate the probability of exocytic dopamine release.45
A maximum release of dopamine at 0.5-1.0 mg/kg AMP (lower at lower doses than at higher doses)
Most of the dopamine released resulted from AMP-stimulated dopamine neosynthesis
The dopamine produced was immediately converted into DOPAC, which is excreted extracellularly
The dopamine was not stored in vesicles
According to Stahl, AMP does not release dopamine, at least at low doses18
AMP caused a gradual 10-fold increase in extracellular dopamine in the striatum over approximately 30 minutes in wild-type mice in vitro and in vivo, while simultaneously reducing the dopamine pool available for electrically stimulated release. If vesicular dopamine was previously released into the cytosol by reserpine, extracellular dopamine did not increase; however, AMP caused a rapid increase in dopamine within 5 minutes. In DAT-KO mice, extracellular dopamine did not increase, but at the same time electrically stimulable dopamine release was also reduced. DAT are therefore required for the dopamine-releasing effect of AMP, but not for the vesicle-emptying effect. Dopamine emptying of the vesicles is the rate-limiting step for the AMP effect on dopamine.64
AMP (10 microm) promoted the release of dopamine from vesicles by reducing the affinity of vesicles for dopamine uptake (from K(m) 0.8 to K(m) 32 microm). However, the amount of dopamine released per pulse was reduced by 82 % (according to another source by 25 to 50 %). The D2 antagonist sulpiride reduced the inhibition of release, i.e. promoted the release. This was reduced in D2-KO mice.
In inhibited D2 autoreceptors, AMP increased the extracellular release of dopamine.43
Emptying of the vesicular DA stores through a weak alkaline effect on the intravesicular pH gradient. The intravesicular pH gradient is required for the concentration of DA.
Different effect on release-ready vesicles and reserve pool vesicles:42
stimulus-dependent effect in the dorsal striatum
stimulates vesicular dopamine release
by a firing of short duration
via vesicle pool ready for release
Release reduced
through a firing of long duration
which accesses the reserve pool
these opposing effects of vesicular dopamine release were associated with simultaneous increases in tonic and phasic dopamine responses
in the ventral striatum
only increased vesicular release and increased phasic signals
Basically, D-amphetamine activates D2 dopamine autoreceptors in the striatum.65
However, drug doses of D-AMP do not cause a significant reduction in dopamine release via activation of the D2 autoreceptors.6667
Since drugs such as levodopa or piribedil show no positive effect in ADHD, although they reduce the firing rate of the dopaminergic neurons of the substantia nigra pars compacta, it is doubtful whether the reduction of hyperactivity in ADHD by stimulants is based on presynaptic inhibition. Presumably, the reduction of hypermotor activity by stimulants in ADHD is rather based on an increase in dopamine release.66
Amphetamine drugs appear to have an activating effect on tyrosine hydroxylase in the dorsal striatum and nucleus accumbens, leading to increased L-dopa levels, but this does not appear to occur via a change in the phosphorylation of tyrosine hydroxylase.68
2.1.5. Increased DA firing / activation in dopaminergic brain regions¶
2.1.5.1. Increased DA firing in caudate nucleus / putamen (striatum)¶
High (well above drug dose) D-amphetamine administration (2.5 to 10 mg/kg in the rat into the abdominal cavity), leads to increased dopaminergic firing in the caudate nucleus and putamen and causes focused-repetitive (stereotypic) behavior.6970 The D2 antagonist haloperidol (2 mg/kg) terminates the excessive firing in the caudate nucleus and putamen and the reduced firing in the nucleus accumbens69
2.1.5.2. Increased DA firing in VTA and substantia nigra¶
D2 antagonists prevent increased firing in the substantia nigra and VTA (in vivo).71
2.1.5.3. Increased activation in the right orbitofrontal cortex, left middle frontal lobe, superior frontal lobe and precentral gyri¶
Improvement in ADHD symptoms with LDX was associated with significantly increased activation in a number of brain regions previously implicated in reinforcement processing under choice and feedback conditions (e.g., left caudate and putamen, right orbitofrontal cortex, left middle frontal lobe, superior frontal lobe, and precentral gyri).72
2.1.6. Reduced DA firing in the nucleus accumbens¶
In the nucleus accumbens, 7.5 mg/kg D-Amp led to a reduction in dopaminergic firing.69 The D2 antagonist haloperidol (2 mg/kg) terminated the excessive firing in the caudate nucleus and putamen and the reduced firing in the nucleus accumbens69
2.1.7. DA influence indirectly via effects on dopamine cells emanating from other brain regions¶
Amphetamine appears to influence the activity of dopamine cells indirectly via its effects on dopamine cells originating in other brain regions.73
Amphetamine can excite dopamine neurons by modulating glutamate neurotransmission. Amphetamine strongly inhibits inhibitory postsynaptic potentials in dopamine neurons mediated by the metabotropic glutamate receptor (mGluR), but has no effect on excitatory postsynaptic currents mediated by the ionotropic glutamate receptor. Amphetamine desensitizes mGluR-mediated hyperpolarization by:74
DA release
Activation of postsynaptic alpha1-adrenergic receptors
Suppression of InsP3-induced calcium release from internal stores
By selectively suppressing the inhibitory component of glutamate-mediated transmission, amphetamine can promote burst firing of dopamine neurons and thus increase the phasic release of dopamine.
Reports of immediate downregulation of dopamine receptors by administration of amphetamine are based on studies in which rats were given doses of amphetamine. This concerns the dosage level (5, 10, 15 mg/kg for 4 or 20 days twice daily) as well as the form (injection).75 Interestingly, a single dose of D-AMP even increased the number of receptors.7567
So far, we are not aware of any reports of downregulation when administered in the dose and form of medication.
Similarly, only studies with drug doses of amphetamines appear to change the dopamine receptor affinity or receptor status from high-affinity to low-affinity. Drug doses could alter the balance between receptor status towards low-affinity.67
More on receptor status at High-affinity and low-affinity receptor status In the article Dopamine effect on receptors
However, it is conceivable that amphetamine in drug doses does not cause a desensitization of the postsynaptic or extrasynaptic (the majority of dopamine receptors are located outside of synapses) D1 and D2 receptors directly, but via the detour of increasing the extracellular dopamine level. However, this hypothesis has not yet been experimentally proven.67 It is possible that this pathway leads to reduced psychomotor activity through amphetamine medication. In our view, however, this is contradicted by the fact that this effect already occurs with the first dose. On the other hand, this pathway could explain why many people with ADHD benefit from a slow and small-step titration of stimulants,
Amphetamine drugs block the dopamine and noradrenaline transporters in a different way to methylphenidate. While the reuptake inhibition of MPH is similar to that of antidepressants, amphetamine drugs act as a competitive inhibitor and pseudosubstrate on dopamine and noradrenaline transporters and bind to the same site where the monoamines bind to the transporter, thereby also inhibiting NE and DA reuptake.4776
“Amphetamines can also stabilize dopamine and noradrenaline transporters in channel configurations, reverse flow through intracellular vesicular monoamine transporters, and cause internalization of dopamine transporters”49
D-amphetamine has about a third of the reuptake inhibition on the noradrenaline transporter (NET) and dopamine transporter (DAT) as racemic methylphenidate.37
Amphetamine (as well as ephedrine) also inhibit the intracellular noradrenaline transporter, which takes up noradrenaline from the nerve cell into the vesicles (the neurotransmitter stores)76
Whether amphetamine has a noradrenaline-releasing effect when administered as a drug is the subject of controversial debate, as is the case with dopamine. There are voices against18 as well as in favor.4648
D-amphetamine secondarily increases the release of noradrenaline.65 This is always the case with dopaminergic drugs due to the conversion of dopamine (approx. 5 - 10 %) into noradrenaline.
There is no doubt that amphetamine drugs do not lead to a chronic depletion of noradrenaline reserves in the sense of a deficiency state. It is empirically proven that amphetamine medication for ADHD does not lead to long-term habituation effects
stereotypical behavior (a sign of strongly increased extracellular dopamine); as strong as 20 mg/kg MPH
extracellular dopamine increased
extracellular noradrenaline increased
extracellular serotonin increased
2.2.3. Reduction of noradrenaline metabolites only in responders¶
In several independent studies, D-amphetamine drugs were found to decrease the urinary metabolite of norepinephrine, MHPG. The decrease of MPHG in urine is thought to be an important indicator of stimulant onset, indicating a lowering of norepinephrine levels by dextroamphetamine drugs.78](https://psycnet.apa.org/psycinfo/1982-21744-001)
Furthermore, the reduction in noradrenaline metabolites only occurs in people with ADHD who respond positively to dexamphetamine (responders).79
Even with the administration of methylphenidate, only the responders showed a significant decrease in MPHG in the urine, while MPHG in the urine of the non-responders did not decrease.80
The authors conclude from this that noradrenaline levels are reduced in ADHD.
Furthermore, several studies with people with ADHD found that behavioral improvements were proportional to the reduced noradrenal metabolite levels (using D-amphetamine medication).81
In contrast to the reduction of metabolites in urine by D-amphetamine, the noradrenaline increase in PFC mediated by D-amphetamine is approximately as pronounced as that of MPH, but is significantly more dose-dependent and therefore more controllable.37
2.2.4. DA firing and DA bursting increased via noradrenaline α1 receptors¶
D-Amp (1 to 2 mg/kg) acts via alpha1-adrenoceptors82 (but not via alpha2- or beta-adrenoceptors) to increase dopaminergic firing and bursting in substantia nigra and VTA (in vivo). This adrenergic pathway is usually masked by the reduction in dopaminergic firing mediated by D2 autoreceptors and is visualized by D2 antagonists or by simultaneous administration of D1/D5 and D2/D3/D4 blockers. The selective norepinephrine uptake blocker nisoxetine did not increase the DA firing rate, but did increase DA bursts.7183
D-amphetamine appears to activate the noradrenaline α1-receptor in the PFC, as the α1-receptor antagonist prazosin completely neutralized the effect of D-amphetamine in the PFC. In contrast, D-amphetamine does not appear to target either the α2 receptor or the β receptor, as the effect of D-amphetamine persisted when the α2 or β receptors were blocked.84
D-amphetamine promotes the up-state of cortical neurons by activating85
Central α1A-adrenoceptors
D1 receptors
D2 receptors
But not by D1 or D2 receptors alone
In contrast, the dopamine/noradrenaline precursor L-DOPA did not promote the up state.
Arousal is associated with an increased up state, while slow-wave sleep, general anaesthesia and calm wakefulness are characterized by an oscillating change between up and down states. During arousal, the down states end and the up/down oscillation changes to a sustained up state.
The up/down oscillations appear to be relevant for memory consolidation, while the transition to a sustained up state is required for arousal and attention.85
Amphetamine drugs act as MAO inhibitors,8638 differently than low-dose MPH. Whether high-dose MPH acts as an MAO inhibitor is unknown.37
MAO is an enzyme that breaks down dopamine and noradrenaline in the cell. MAO inhibitors thus increase the amount of dopamine and noradrenaline available in the cell. As dopamine and noradrenaline continue to be synthesized in the nerve cell, the noradrenaline and dopamine levels in the cell continue to rise. This leads to a reversal of the effect of the transporters (which actually return DA and NE from the synaptic cleft into the cell), so that they release NE and DA into the synaptic cleft, even without this being triggered by a nerve signal to be transmitted.86 This effect triggers peripheral hypertension and an increase in heart rate. As this mechanism of action occurs indirectly at the presynapse, ephedrine and amphetamine drugs are also called “indirect sympathomimetics”, while active ingredients that act directly at the postsynaptic receptors are called sympathomimetics.86
Amphetamine drugs are said to release a small amount of serotonin.8717 Here, too, it is unclear whether this is really also the case when dosed at drug level, or whether this effect is only limited when dosed as drugs. In any case, Stahl does not report a serotonergic effect of amphetamine drugs.47
stereotypical behavior (a sign of strongly increased extracellular dopamine); as strong as 20 mg/kg MPH
extracellular dopamine increased
extracellular noradrenaline increased
extracellular serotonin increased
Serotonin release through amphetamine drugs
Amphetamine drugs (MDMA, MBDB) also increase the release of serotonin. It is assumed that amphetamine-induced serotonin release not only influences psychomotor activation, but also subjective well-being (and euphoria when taken as a drug).88 MDBD causes almost no dopamine release.
Hyperactivity induced by 5 mg or 10 mg / kg MDMA (= 10 to 20 times higher dosage than as medication) could be prevented by prior administration of 2.5 and 10 mg / kg of the selective serotonin reuptake inhibitor fluoxetine. Fluoxetine had the same effect on the interactive effect of MDMA and P-chloroamphetamine.89 This suggests that MDMA causes hyperactivity by increasing serotonin via the serotonin transporter, which was blocked by fluoxetine as a serotonin reuptake inhibitor.
There is evidence that an increased release of serotonin indirectly increases dopamine levels.89
Other sources point to a serotonin-increasing effect of amphetamine salts due to inhibition of monoamine oxidase.20
Amphetamine increases c-Fos expression in the mPFC, striatum and nucleus accumbens. A serotonin 1A receptor agonist reduced the c-Fos increase in the mPFC and striatum, but not in the nucleus accumbens.90
MPH itself has an agonistic effect on the 5-HT1A receptor.38
D-amphetamine drugs such as lisdexamphetamine drugs (Vyvanse) increase cortisol levels but not testosterone levels.91
The following were increased
Glucocorticoids (as with methylphenidate; the increase was even greater with the drugs MDMA or LSD)
Cortisol
Cortisone
Corticosterone
11-Dehydrocorticosterone,
11-Deoxycortisol
The following remained unchanged
Mineralocorticoids
Aldosterone
11-Deoxycorticosterone
The increase in the cortisol level causes a stronger addressing of the glucocorticoid receptor (GR) by cortisol. Cortisol causes the HPA axis to be switched off again via GR at the end of the stress response.
In ADHD-HI and ADHD-C (both with hyperactivity), due to the flattened endocrine stress response of the adrenal gland, it can be assumed that the GR are not sufficiently addressed to switch off the HPA axis again after a stress reaction. In addition, in ADHD-HI (unlike ADHD-I) there is often deficient GR function, which makes HPA axis deactivation even more difficult.
Find out more at Medication for ADHD at ⇒ Dexamethasone for ADHD. If the release of cortisol is increased by AMP, this could improve the resilencing of the HPA axis in ADHD-HI. However, as AMP also works in ADHD-I, the primary mechanism of action is likely to be different.
Lisdexamfetamine and d-amphetamine significantly increased plasma levels in healthy subjects of, among others:91
Androgens
Dehydroepiandrosterone
Dehydroepiandrosterone sulfate
Androstenedione (Δ4-androstene-3,17-dione)
Progesterone (only for men)
The androgen remained unchanged
Testosterone
Since aggression correlates with an increased testosterone to cortisol ratio, amphetamine drugs have an anti-aggressive effect due to the relative increase in cortisol levels.
More on this at ⇒ Neurophysiological correlates of aggression
A study in adolescent rhesus monkeys found that both active ingredients increased testosterone levels, MPH even more than AMP, as a consequence of 12 months of AMP or MPH administration in drug doses.92 Another study in rhesus monkeys found reduced testosterone levels with MPH administration.93
A reduction in testosterone levels was observed in rodents following amphetamine administration.9495
Organic cation transporter 2 (OCT2) is involved in the degradation of dopamine. OCTs take up dopamine and noradrenaline as well as serotonin and, to a somewhat greater extent, histamine in glial cells, where they are broken down by COMT. OCT2 and OCT3 are also located on (also dopaminergic) neurons.
While methylphenidate only binds to OCT1 (IC50: 0.36) and neither to OCT2, OCT3 nor PMAT96, d-amphetamine acts as a highly effective hOCT2 reuptake inhibitor (Ki: 10.5 mM) and moderately effective hOCT1 reuptake inhibitor (Ki: 202 mM), while it only interacted with hOCT3 from 100 μM (Ki: 460 mM) (hOCT: human OCT) 9697
d-Amphetamine binds approximately equally strongly to hOCT2 and hOCT3 and to these by an order of magnitude (factor 10) weaker than to DAT97
Binding of amphetamine to OCT may contribute to cellular and behavioral effects of amphetamine.97
OCT2 reuptake inhibitors have an antidepressant effect.98 In addition, even much lower doses of venlaflaxine or reboxetine have an antidepressant effect in OCT2-KO mice than in wild-type mice99
We think it is worth considering whether this approach could also support the effect of dopamine reuptake inhibitors in ADHD.
These correlations could also explain why AMP, which also acts as an OCT2 inhibitor, has a better antidepressant effect than MPH, which only binds to OCT1.
D-amphetamine increases metabolism in the right caudate nucleus and decreases it in the right Rolandic region and in the right anterior inferior frontal regions.100
D-amphetamine (as well as L-dopa, which has no effect on ADHD, although it has a dopaminergic effect) is also suitable for restoring brain function after strokes, but only if suitable training measures are taken at the same time.101 D-amphetamine increases dopamine, which has a neurotrophic effect (promotes neuroplasticity). Dopaminergic drugs such as (D-)amphetamine drugs or MPH can therefore also support appropriate training measures (e.g. neurofeedback, cognitive behavioral therapy) in ADHD by reducing the restrictions on learning ability.
Methylphenidate and amphetamine drugs increase the power of alpha (in rats), while atomoxetine and guanfacine do not.102
Lisdexamfetamine (Vyvanse) has the following effects103
Increased acetylcholine levels in the cortex
Increased histamine levels in the cortex and hippocampus (which escitalopram given in parallel only prevents in the hippocampus)
Amphetamine medication is therefore not just a substitute for methylphenidate, but has its own area of application.
2.8.1. Binding affinity of AMP, MPH, ATX to DAT / NET / SERT¶
The active ingredients methylphenidate (MPH), d-amphetamine (d-AMP), l-amphetamine (l-AMP) and atomoxetine (ATX) bind with different affinities to dopamine transporters (DAT), noradrenaline transporters (NET) and serotonin transporters (SERT). The binding causes an inhibition of the activity of the respective transporters.104
The values given in the following table by Easton et al. refer to values in the synaptosome as well as to the DAT in the striatum and the NET in the PFC.
Binding affinity: stronger with smaller number (KD = Ki)
2.8.2. Effect of AMP, MPH, ATX on dopamine / noradrenaline per brain region¶
The active ingredients methylphenidate (MPH), amphetamine (AMP) and atomoxetine (ATX) alter extracellular dopamine (DA) and noradrenaline (NE) to different degrees in different regions of the brain. Table based on Madras,104 modified.
PFC
Striatum
Nucleus accumbens
MPH
DA + NE (+)
DA + NE +/- 0
DA + NE +/- 0
AMP
DA + NE +
DA + NE +/- 0
DA + NE +/- 0
ATX
DA + NE +
DA +/- 0 NE +/- 0
DA +/- 0 NE +/- 0
3. Effect of amphetamine medication compared to MPH / atomoxetine¶
In MPH nonresponders, lisdexamfetamine (EU: Vyvanse) and atomoxetine were compared in a randomized double-blind study with n = 200 subjects. Lisdexamfetamine was significantly more effective than atomoxetine in 2 of 6 categories and in the overall assessment.105
Lisdexamfetamine (EU: Vyvanse) also had a good effect on comorbid depression symptoms in a double-blind study.106MPH is not known to have any positive effects on depression symptoms.
A 2-year study in children and adolescents (n = 314) showed a responder rate of between 70 and 77 % with good efficacy and manageable side effects.107
In people with ADHD who respond positively to D-amphetamine medication as well as MPH, the effect of D-amphetamine medication is at least equal to MPH108, and in our experience in adults even significantly better.
According to the current European consensus, amphetamine medication is the first choice of medication for ADHD in adults (before methylphenidate) and the second choice of medication in children (after methylphenidate).67
Amphetamine medication should also always be tried if MPH does not work (non-responder).
MPH has a stronger activating and drive-enhancing effect on most people with ADHD than AMP medication. Contrary reports109 are not consistent with our experience.
Statements in the specialist literature that amphetamine medication is more suitable for people with ADHD-I than MPH, partly because people with ADHD-I are above-average AMP nonresponders,110 cannot be confirmed from our experience either
We know several persons with ADHD-HI who are significantly better helped by amphetamine medication than MPH and people with ADHD-I who cope better with MPH. We are not aware of any subtype-specific effect of amphetamine medication or methylphenidate. In our experience, amphetamine medication works just as well for ADHD-HI as for ADHD-I.
People with ADHD have reduced extrinsic and intrinsic motivation. For example, they need higher rewards to be just as motivated for something as non-affected people. However, once motivation is awakened in persons with ADHD, their attention and controllability can no longer be reliably distinguished from that of non-affected people. ⇒ Motivational shift towards own needs explains regulation problems
Attention correlates with a deactivation of the default mode network (DMN), among other things. Stimulants are able to align the attentional control of people with ADHD (or the motivational capacity, from which attention follows) with that of non-affected people, which is then also reflected in a normalization of DMN deactivability.111
More on the deviant function of the DMN in ADHD and its normalization by stimulants, including further sources at ⇒ DMN (Default Mode Network) In the article ⇒ Neurophysiological correlates of hyperactivity.
The cited references refer to the effect of methylphenidate. However, it can be assumed that the effect is achieved by stimulants in general.
People with ADHD report that MPH allows for greater focus, while amphetamine medications (Vyvanse) tend to create a more relaxed general alertness and have a slightly more pleasant effect overall.
Amphetamine medications probably also have a mild serotonergic effect and thus have a special area of application in comorbid dysthymia or depression, especially since serotonin reuptake inhibitors (SSRIs) can have adverse effects in ADHD (especially ADHD-I) (see there).
In forums, a number of people with ADHD report a significant antidepressant effect from amphetamine medication, which they are not familiar with from MPH.112 This is consistent with the experiences of users known to us.
As amphetamines can have a stronger drive-increasing effect than MPH, this can release an existing suicidal tendency that was not previously carried out due to the existing depression. Amphetamine medication should therefore be used with caution in cases of (even concealed) severe depression.
Attention: a supposed dysthymia (mild chronic depression) in people with ADHD must be clearly differentiated from the original ADHD symptom of dysphoria during inactivity.
Find out more at ⇒ Depression and dysphoria in ADHD In the section ⇒ Differential diagnosis of ADHD.
Comorbid anxiety disorders or depression can be exacerbated by stimulants, as anxiety and moods are regulated by the dopaminergic activity of the ventromedial PFC in conjunction with the limbic system.47
Amphetamine drugs have a very long duration of action (up to 13 hours). Taking it too late (less than 14 hours before going to bed) could therefore cause problems falling asleep. In contrast, some people with ADHD who take amphetamines report feeling pleasantly tired in the evening and that they no longer have problems falling asleep.
Studies show that amphetamine medications improve overall sleep quality in ADHD.113114
Response here means whether there is an effect on the ADHD symptoms. People with ADHD who do not respond sufficiently to a medication are called non-responders.
Non-responding does not mean having no effect, but merely that the effect remains below the level of symptom improvement specified in the respective study.
One study reported a responder rate of 80% (defined as an improvement of more than 30% in ADHD-RS-IV scores and CGI-I scores of greatly improved or very greatly improved)116
A summary of several studies reports a 69% response rate to amphetamine medication and a 59% response rate to methylphenidate. 87 % of the people with ADHD responded to one of the two types of drugs.12
A 2-year study of L-amphetamine medication in children and adolescents (n = 314) showed a responder rate of between 70 and 77% with good efficacy and manageable side effects.107
For MPH non-responders, it is therefore highly recommended to test a medication with amphetamine drugs (see 1.2.), and vice versa.
In carriers of the COMT Val-158-Met gene polymorphism, amphetamine increased the efficiency of the PFC in subjects with presumably low levels of dopamine in the PFC. In contrast, in carriers of the COMT Met-158-Met polymorphism, amphetamine had no effect on cortical efficiency at low to moderate working memory load and caused a deterioration at high working memory load. Individuals with the Met-158-Met polymorphism appear to be at increased risk for an adverse response to amphetamine.117
Amphetamine drugs do not appear to show any gender-specific differences in effect.118
7. Calming effect at low doses, activating at high doses¶
D-amphetamine appears to have a biphasic action profile. Low doses of 0.5 to 1 mg/kg in rats (equivalent to about 0.2 to 0.6 mg/kg in humans) reduce (hyper)activity, while higher doses increase it.41
About 66% of all persons with ADHD respond equally well to MPH as to amphetamine medication.
22% respond better to amphetamine drugs than to MPH.
11% respond better to MPH than to amphetamine drugs.119
Around 15% of people with ADHD respond best to the active ingredient D-amphetamine.120
According to this result, it would make more sense to first try therapy with amphetamine medication and only try MPH as a second option in the case of non-response, as people with ADHD respond somewhat better to amphetamine medication than to MPH.
Highly gifted people with ADHD (here: IQ > 120) are said to respond better to amphetamine medication than less gifted people with ADHD.121
An interesting study discusses the effectiveness of lisdexamfetamine.122
It is advisable to start with a very low dosage, which is then slowly increased. Even if the optimal dosage were known, an immediate optimal dosage would possibly lead to excessive demands.123 The symptoms of ADHD are caused by signal transmission problems between the brain nerves because the neurotransmitter level (dopamine, noradrenaline) is too low. An optimal neurotransmitter level corrects the signal transmission problems. If the neurotransmitter level is too high due to an overdose, signal transmission is just as impaired as if the level is too low.
This explains why low doses should be given at the beginning and then, with persistent persistence, higher doses should be given until a worsening of symptoms is observed.
As the number of dopamine transporters in adults is half that of 10-year-olds, it is advisable to start with a much lower dosage than in children.
9. Effect profile (temporal) / duration of action¶
In replicated studies on the duration of action of amphetamine drugs, children had a shorter half-life of around 7 hours, while adults had a longer half-life of around 10 to 12 hours124
The time course of the effect (effect profile) depends less on the active ingredients than on the specific composition of the medication.
Vyvanse has a very elongated effect profile without pronounced peaks, so that barely any flooding or rebound effects are noticeable. See: Graphic representation of the Vyvanse effect profile. However, the graph from Shire’s patent application refers to the plasma level in rats at an extremely high dose of 3 mg/kg.
The extent to which the binding of D-amphetamine to lysine in lisdexamfetamine really leads to a flattened and prolonged concentration of amphetamine in the blood plasma remains to be seen. A single dose of 40 mg D-amphetamine or 100 mg lisdexamfetamine (above the medically appropriate doses) in healthy people showed no relevant differences in amphetamine blood plasma concentration.125 Furthermore, the study data probably indicate a subjective impression of a gentler and longer effect of lisdexamfetamine on the part of the test subjects, although the authors do not report this. A further limitation of the study is that the subjects were treated with a single dose and there was no dosing to the tested dosage. The authors themselves cite studies showing that amphetamine drugs require familiarization phases or show (initial) habituation effects. The results of the study are therefore primarily of pharmacological interest, but only of limited practical use.
Empirically, adults report quite unanimously of a gentler and prolonged effect of lisdexamfetamine. The majority cite 5 to 7 hours as the duration of action of a single dose. There is also a fairly unanimous report of a very slow onset of action, with 1 to 2 hours being mentioned in most cases.
The surveys are not representative (no consideration of age, weight, dose level or gender), but clearly show that a duration of action of 13 or 14 hours, as stated by the manufacturer, is only exceptionally achieved in adults in practice.
A more detailed Survey on the single-dose duration of action of all ADHD medicationswhich also includes the aforementioned secondary factors, has been running since March 2023 and could show initial results in fall 2023.
Many people with ADHD (we know of dozens of cases from the forum) take 2 or 3 single doses of Vyvanse per day to achieve the required all-day coverage, even if this does not comply with the manufacturer’s instructions. The individually shortened duration of action could also be a consequence of a low dosage of often 30 mg or less per single dose, which was chosen when an overdose was perceived at a higher single dose during the phase of high D-AMP blood plasma levels. In almost no person with ADHD does the sum of the single doses exceed 70 mg / day.
The result of taking multiple smaller doses of Vyvanse on D-AMP blood plasma levels could (hypothetically) look like this:
10. Areas of application of amphetamine drugs in relation to MPH¶
According to the current European consensus on the diagnosis and treatment of ADHD in adults, amphetamine medication is the first choice of medication for ADHD in adults (before methylphenidate) and the second choice of medication for children (after methylphenidate)67
In children who are MPH non-responders, i.e. who do not respond to MPH, the efficacy of amphetamine medication should be tested.
People with ADHD with pronounced dysphoria during inactivity or with comorbid depression benefit particularly from amphetamine medication.
In addition, people with ADHD who require stronger activation may be able to cope better with amphetamine medication.
Highly gifted people are said to respond better to amphetamine medication than to MPH.121
11.1. No liver damage with normal medication dosage¶
High doses of amphetamines may be associated with liver damage and certain forms of clinically apparent liver damage. This is most commonly reported with methylenedioxymetamphetamine (MDMA: “ecstasy”).126
AMP increases histamine,127128 as do all other known ADHD medications:
Atomoxetine
Methylphenidate
Modafinil
Nicotine
Caffeine
Therefore, people with histamine intolerance often have problems due to taking ADHD medication.
A person with ADHD with histamine intolerance reported that she could not tolerate AMP and sustained release MPH at all, but could tolerate immediate release MPH in small doses.
Several large studies found no increased risk of serious cardiovascular events such as stroke, heart attack or cardiac arrhythmia for amphetamine drugs.129130
A study over 14 years found a 4% increase in the risk of cardiovascular problems per year of taking stimulants (methylphenidate, amphetamines) and, to a lesser extent, the non-stimulant atomoxetine.131
The package insert for Vyvanse mentions erectile dysfunction in 1 to 10 out of 100 men. However, the specialist literature or studies do not report any sexual impairments caused by amphetamine medication.
Reports from the ADxS-ADHD forum sometimes report erection problems with amphetamine medications, but barely with MPH.
Two male persons with ADHD reported a loss of sensitivity in the genital area after consuming red wine outside the active period of the regularly taken Vyvanse. In one of the persons with ADHD, low nicotine consumption outside the active period is another suspicious factor.
A single case report documents a reduction in testosterone and other sex hormones and a reduction in sperm count from an amphetamine medication, which was reversed by switching back to MPH.133
Amphetamine drugs also bind to alpha1-adrenoceptors (see above).
A blockade of alpha1-adrenoceptors leads to a delayed detumescence of the erectile tissue and thus to a reduced ability to ejaculate and orgasm, both in women and in men.134 Blockade is the opposite of binding. Dopamine agonists such as L-dopa or bromocriptine cause an increase in sexual desire and sexual activity.
Amphetamines (usually in drug use) can alter spermatogenesis and lead to oxidative stress and subsequent apoptosis in testicular tissue135
Amphetamine in drug doses (here: lisdexamfetamine) did not change the testosterone level.136
Amphetamine (in drug doses) is able to reduce testosterone production in rodents and increase the formation of cyclic AMP in the testes135
A single intravenous injection of amphetamine (administered as a drug) reduced hCG-stimulated testosterone release. The LH plasma level remained unchanged.
Amphetamine thus appears to have a direct and dose-dependent effect on Leydig cells, where it inhibits testosterone production by activating adenylate cyclase.94
A single intraperitoneal administration of methamphetamine initially lowered serum testosterone and increased it to a level above baseline after 48 hours.137 Chronic high methamphetamine administration decreased testosterone138 and increased GABA in the testes.139GABA is involved in the proliferation of Leydig cells and testosterone production.
MDMA inhibits the hypothalamic-pituitary-gonadal axis in male rats. Both acute and chronic MDMA administration caused decreased serum testosterone and GnRH mRNA expression. LH, progesterone and estradiol remained unchanged. This indicates a reduced drive by hypothalamic GnRH neurons as a cause of inhibition of the hypothalamic-pituitary-gonadal axis.140
Subcutaneous MDMA administration for 12 weeks on three consecutive days/week (simulating human weekend use) did not alter the hormones of the hypothalamic-pituitary-gonadal axis.141
Methamphetamine can trigger apoptosis in testicular germ cells of mice142143 and reduce sperm count.144
Rats receiving 5 ml/kg methamphetamine intraperitoneally for 7 and 14 days (drug dose) showed significantly decreased spermatogonia, primary and secondary spermatocyte counts and spermatogenesis indices (tubule differentiation index, spermiogenesis index, repopulation index and mean testicular tubule diameter).145
MDMA is also capable of inducing histological changes in the testicles of rats and causing DNA damage to the sperm in a dose-dependent manner. However, the sperm count increased and the spermatid count decreased.141 MDMA increased the body temperature and the immunoreactivity of heat shock protein 70 (HSP70), which could activate apoptosis in the testicular tissue of the rat.146
A pilot study in men with sexual problems reported improvements in subjective sexual experience (reduced time to orgasm or increased frequency of orgasm) with 5 to 20 mg amphetamine salts (Adderall) 1 to 4 hours before sexual activity (up to 10 doses/month)147
In 5 individual cases, the resolution of SSRI-induced sexual dysfunction by small doses of dextroamphetamine or methylphenidate was reported.148 Further case studies report multiple erections (15-year-old), hypersexual behavior (8-year-old) due to OROS-MPH (Concerta)149 and priapism (14-year-old).150
One study reported a doubled rate of testosterone deficiency in adult persons with ADHD after 5 years of stimulant use (1.2%) compared to persons with ADHD without stimulant use (0.67%) or non-stimulant use (0.68%).151
Lisdexamfetamine (Vyvanse) is converted to d-AMP in the blood cytosol of erythrocytes by an unknown amino acid (presumably an aminopeptidase)155156 by cleaving the covalent bond between d-amphetamine and L-lysine. Only d-AMP is pharmacologically active.
D-AMP is metabolized faster than l-AMP, so that the exposure of d-AMP lasts 9-11 hours and of l-AMP 11-14 hours.
Taking it together with a high-fat meal can extend the half-life of d-AMP by one hour.
A study came to other conclusions, according to which CYP2D6 may barely be involved in the degradation of AMP.158 Other studies also tend to indicate that amphetamine itself is metabolized much less by CYP2D6 than some amphetamine analogues.159160
Nevertheless, amphetamine is a strong CYP2D6 inhibitor.160
AMP is primarily excreted via the kidneys.
Since AMP is slightly basic (pKA = 9.9), AMP excretion is highly dependent on urine pH and flow rate, with recovery of AMP in urine ranging from 1% to 75% and the remainder being metabolized hepatically:28
normal urine pH values
30 to 40 % of the AMP dose is largely excreted as unchanged parent compound
50% of the dose is excreted as alpha-hydroxyamphetamine or its downstream inactive metabolite, hippuric acid.
acidic urine (pH <6.0)
accelerated AMP excretion
alkaline urine (pH >7.5)
delayed AMP excretion
The half-life of AMP should increase by 7 hours per unit of pH increase. Acidifying or alkalizing agents can therefore significantly alter the effect of AMP.
12.3. Duration of action of AMP; influence of CYP2P6 metabolism types¶
The CYP2D6 gene is highly polymorphic. In Central Europe, the following alleles are particularly relevant161
CYP2D6*3
CYP2D6*4
CYP2D6*5
CYP2D6*6
CYP2D6*9
CYP2D6*41
Poor metabolizers are likely to require lower AMP doses and ultra-rapid metabolizers are likely to require higher AMP doses. However, the effects of CYP2D6 polymorphisms on AMP metabolism are still unclear.28
Based on the experience with the influence of CYP2D6 on the effect of other drugs (CYP2D6 is responsible for the metabolization of 20 - 30 % of all drugs), the different CYP2D6 gene variants lead to different types of metabolization161
Slow metabolizers - approx. 7 %
particularly slow dosing is important
particularly low dosage helpful
moderately fast metabolizers - approx. 40 %
Fast metabolizers - approx. 46 %
Ultra-fast metabolizers - approx. 7 %
CYP2D6*XN allele
increased enzyme activity
is associated with therapy resistance (non-responders)
Two online surveys of a total of around 550 people with ADHD who take Vyvanse showed that around 40% have a duration of action of 5 hours or less and two thirds have a single-dose duration of action of 7 hours or less. More on this under Effect and duration of action of ADHD medication
A cohort study found no increased risk of ADHD or other neuronal developmental disorders from MPH or AMP use during pregnancy.163
One study found no reduction in the weight of newborns of mothers with ADHD who took amphetamine medication during pregnancy.164 This is consistent with results from a large cohort study of MPH use during pregnancy.165
Another comprehensive study found a slight reduction in birth weight and a slight increase in the risks of pre-eclampsia, placental abruption or premature birth when taking stimulants (AMP or MPH) during pregnancy, although this was so small that the authors did not recommend discontinuing stimulant use during pregnancy.166 Atomoxetine did not show these slight increases in risk.
Another Danish cohort study found a doubled risk of miscarriage when taking stimulants during pregnancy.167
Another Danish cohort study found an increase in malformations in children of mothers who had taken MPH in the first trimester of pregnancy, but the authors did not consider this to be relevant.168 A smaller study found no increased risk.169
One study found no disadvantages for the child if the mother continued to take D-Amp during pregnancy. However, if D-Amp intake was discontinued during pregnancy, there was an increased risk of abortion. There were advantages if no D-Amp was taken before and during pregnancy. Early discontinuation could therefore be helpful if you wish to have children.170
Hypersensitivity to the active ingredient
Monoamine oxidase inhibitors (MAO inhibitors) at the same time or 14 days before use
Risk: hypertensive crisis
Hyperthyroidism / thyrotoxicosis
Excitation states
Symptomatic cardiovascular disease
Advanced arteriosclerosis
Moderate to severe hypertension
Glaucoma
Serotonin reuptake inhibitors
The risk of serotonin syndrome should be taken into account when administering SSRIs and amphetamine medication at the same time.20
According to a very large study, the risk of developing psychosis is lower for people with ADHD taking MPH (0.10%) than for those treated with amphetamine medication (0.21%).171 While people with ADHD treated with stimulants have 2.4 cases of psychosis per 1000 person-years, the figure for the population as a whole is 0.214%.172 The studies do not allow any conclusion to be drawn as to whether the increased prevalence of psychosis is attributable to ADHD or stimulants.
Substances that lower the pH value in the gastrointestinal tract
e.g:
Guanethidine
Reserpine
Glutamic acid
Hydrochloric acid
Ascorbic acid
Fruit juice
cause reduced absorption of dexamphetamine
Substances that acidify urine (ammonium chloride, sodium dihydrogen phosphate, etc.)
increase ionized excretion products of dexamphetamine in urine, resulting in increased renal excretion
Acidification of the urine (reduced pH value)162
e.g. through
Ascorbic acid
Thiazide diuretics
High protein diet
Diabetes mellitus
Caution: Foods that taste acidic often have an alkalizing effect in the body beyond the digestive tract.
Example: Lemon juice has a pH value of 2.4 and therefore has an acidic effect on the mouth and stomach. After digestion, however, only an alkaline residue remains in the rest of the body, which increases the pH value.
The effect of food after digestion on the acid load of the kidneys due to minerals and protein is indicated by the PRAL value (potential renal acid load). This value is not suitable for assessing the acid load of the mouth and stomach (as is relevant for heartburn).
The higher the PRAL value, the more acidic the effect on the kidneys and the rest of the body after the digestive organs.
Urine pH has been shown to be a good PRAL marker. An alkaline urine pH value correlates with a diet with a negative PRAL value, while urine pH values below 6.0 correlate with an acidifying diet.
A distinction must be made between plant and animal proteins. After 7 days of a vegetarian diet, the pH urine value increases and the PRAL value decreases, as does 2 or 3 days of a vegetarian diet per week.174 A vegetarian diet thus correlates with a prolonged amphetamine drug effect.
Foods with a high oxalate content can increase acid formation.175
One study gives the following calculation method:176 PRAL (mEq/d) = 0.49 x protein (g/d) + 0.037 x phosphorus (mg/d) - 0.021 x potassium (mg/d) - 0.026 x magnesium (mg/d) - 0.013 x calcium (mg/d).
In other words, foods with a strongly negative PRAL value cause alkaline (less acidic) urine and thus promote a prolonged effect of amphetamine drugs. Foods with a high PRAL value cause acidic urine and thus promote a shortened effect of amphetamine drugs. According to this model, hard cheese is suitable for shortening the effects of amphetamine drugs, while raisins could prolong them.
Substances that increase the pH value in the gastrointestinal tract increase dexamphetamine uptake
e.g:
Sodium bicarbonate (baking powder)
Substances that increase urine pH increase non-ionized excretion products in urine, which decreases renal excretion and thus increases blood levels of dexamphetamine
e.g:
Acetazolamide
some thiazides
There is evidence that reduced expression of the CACNA1C gene can lead to a prolonged effect of dopamine reuptake inhibitors.177 Conversely, increased CACNA1C expression may lead to a shortened effect.
Lisdexamfetamine (Vyvanse) has a maximum blood level that is delayed by one hour with high-fat meals (4.7 hours instead of 3.8 hours after ingestion).178 However, other parameters, such as the duration of action, do not change.
As amphetamine is broken down by CYP2D6, drugs that are also broken down by CYP2D6 can slow down the breakdown of amphetamine as well as their own breakdown, as competition for the CYP2D6 enzyme arises.
CYP2D6 inhibitors can increase amphetamine levels, making a dose reduction necessary. After discontinuation of CYP2D6 inhibitors, an increase in the dose of amphetamine medication may be necessary.179
CYP2D6 inducers can accelerate degradation and thus reduce the effect.
A single person with ADHD reported a loss of efficacy of Vyvanse due to Dienogest 2 mg (Zafrilla) in endometriosis, while the effect of Attentin remained unchanged.
13.6. Few interactions of AMP with other medications¶
In contrast to the above-mentioned interactions of amphetamine drugs with other drugs, barely any interactions of amphetamine drugs with other drugs are known.179
Amphetamine is said to have a slight inhibitory effect on the cytochromes
A small prospective study of n = 13 children whose mothers received amphetamine medication while breastfeeding found no disadvantages for the children.181
14. Long-term effect: No habituation effects of amphetamine medication¶
A meta-analysis of 87 randomized placebo-controlled double-blind studies found no evidence of a decrease in the effect of methylphenidate, amphetamine drugs, atomoxetine or α2 antagonists with prolonged use.182
Mixture of D- and L-amphetamine isomers (racemic mixture)
Mixed sulfates and saccharinates of D-L-amphetamine isomers (Adderall)
Pure D-amphetamine sulphate
Dexamfetamine hemisulfate (Attentin)
D-amphetamine as lisdexamfetamine in lysine-bound form (Vyvanse, Tyvense)
Racemic methamphetamine sulphate (Desoxyn)
Vyvanse, Tyvense
Vyvanse / Tyvense contains lisdexamfetamine. Lisdexamfetamine is dextroamphetamine bound to lysine. The lysine binding causes a very slow and even release of dextroamphetamine in the blood and thus a prolonged effect.
Available in the USA:
Capsules: 10, 20, 30, 40, 50, 60, 70 mg
Chewable tablets: 10, 20, 30, 40, 50, 60 mg
Lahey (Hrsg.) (2012): Advances in Clinical Child Psychology, Band 9, S. 187, mit Verweis auf [Brown, Ebert, Hunt, Rapoport (1981): Urinary 3-methoxy-4-hydroxyphenylglycol and homovanillic acid response to d-amphetamine in hyperactive children; Biological Psychiatry, Vol 16(8), Aug 1981, 779-787 ↥
