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Amphetamine

Brands and Forms

Amphetamine has two basic forms, or isomers: d-amphetamine (or dextroamphetamine) and l-amphetamine (or levoamphetamine). D-amphetamine is the active ingredient in Dexedrine, Dextrostat and Dexedrine Spansules. A mixture of d- and l-amphetamine is contained in Adderall and Adderall XR.

Lisdexamfetamine (Vyvanse) is another form of amphetamine that has a lysine amino acid bonded to a d-amphetamine molecule. This form of the drug remains inactive until the lysine portion is removed during digestion in the intestine, at which point the d-amphetamine portion can become active.

  • Dexedrine
    • immediate-release tablet: 5mg scored, 10mg
  • Dextrostat
    • immediate-release tablet: 5mg, 10mg
  • Dexedrine Spansules
    • extended-release capsule: 5mg, 10mg, 15mg
  • Adderall
    • immediate-release double-scored tablets: 5mg, 7.5mg, 10mg, 12.5mg, 15mg, 20mg, 30mg
  • Adderall XR
    • extended-release tablet: 5mg, 10mg, 15mg, 20mg, 25mg, 30mg
  • Vyvanse
    • extended-release capsule: 20mg, 30mg, 40mg, 50mg, 60mg, 70mg

Uses of Amphetamine

Amphetamine is commonly used to treat ADHD and Narcolepsy. It may also be used in cases of treatment-resistent Depression.

How Amphetamine Works

Amphetamine is in the class of the Stimulants. It increases norepinephrine and dopamine actions by blocking their reuptake and facilitating their release.

Lisdexamfetamine was designed to prevent abuse of the amphetamines, such as when amphetamines are snorted or injected intravenously. Because lisdexamfetamine remains unactive until the lysine portion of the molecule is cleaved in the GI tract, it can only work when taken orally.

Cautions when Using Amphetamine

In people with heart disease (especially cardiac structural abnormalities), cardiovascular disease, hypertension, hyperthyroidism, a seizure disorder, or glaucoma, advice from the appropriate medical specialist should be obtained before starting Amphetamine.

Amphetamine can worsen states of anxiety and agitation. It can worsen or induce psychosis in people with Psychotic Disorders, and can worsen or induce Manic or Mixed Episodes in people with Bipolar Disorder. Amphetamine can also induce or exaccerbate tics in people with a Tic Disorder.

Amphetamine can be abused and lead to dependence, and thus may not be appropriate for people with a history of drug abuse.

Amphetamine should not be used during or within 14 days following the administration of an MAOI, because a hypertensive crisis may result.

Dosing of Amphetamine

The optimal dose of Amphetamine is one where the individual is experiencing clinical benefits without enduring signficant side-effects. This dose can be different from person to person, ranging from 5-60mg/day for any of the forms of Amphetamine.

To determine the right dose for an individual, one should choose an immediate release form of Amphetamine, such as Dexedrine, Dextrostat, or Adderall. These forms give an effect that lasts about 4-6 hours. They should be started at 5mg once in the morning and once about four or five hours later, around noon. Within a few days, the individual will be able to report on whether they feel any effect from this dose.

If they are already experiencing significant side-effects at this dose, then it means that it is likely not the right medication for them.

If they report that they are feeling clinical benefits at this dose, and without too much in the way of side-effects, then this dose should be continued.

Most likely, this dose will be too small to give much of an effect, especially in adults. The next step is to increase the two daily doses each by 5mg every few days until the point is reached where the individual is experiencing benefits without signficant side-effects. This point will be the optimal dose. If, in this process, the individual begins to run into significant side-effects before they experience any benefits, then the medication will likely need to be stopped.

Once the optimal dose is found, it may be more convenient to switch to a long-acting form of Amphetamine, such as Dexedrine Spansules or Adderall XR, which only need to be taken once a day in the morning, and give a smoother, more even effect throughout the day that lasts for about 12 hours.

The daily dose of either of these long-acting forms will be equal to the total daily dose that was used for one of the short-acting forms. For example, Adderall 20mg twice a day will be equivalent to Adderall XR 40mg once a day.

The one exception to this rule is with Lisdexamfetamine (Vyvanse); Lisdexamfetamine 25mg daily is equivalent to Amphetamine 10mg daily.

Onset of action

Therapeutic effect in ADHD can be seen as soon as the first day of use. Can take several weeks to attain maximum therapeutic effect. If no significant effects are seen after a few days at a dose where the patient is already experiencing side-effects, then it likely will not work at all.

Kidney impairment

Dose adjustment not necessary.

Liver impairment

In patients with moderate hepatic impairment (Child-Pugh class B), reduce normal doses by 50%. In patients with severe hepatic function impairment (Child-Pugh class C), reduce normal doses by 25%.

Side-effects of Amphetamine

Below is a list of most of the reported side-effects of Amphetamine. Most of these side-effects occur in only a minority of individuals, and many also resolve with time while the medication is continued.

Cardiovascular: palpitations; tachycardia; elevation of blood pressure; arrhythmias; see also serious side-effects.

Central Nervous System: dizziness; headache; insomnia; dyskinesia; tremor; exacerbation of motor and phonic tics; see also serious side-effects.

Endocrine: evidence shows that Amphetamine does not cause significant suppression of normal growth in children [ref].

Eyes, Ears, Nose and Throat: dry mouth; unpleasant taste; blurred vision; worsening of glaucoma.

Gastrointestinal: nausea; diarrhea; constipation; abdominal pain; loss of appetite; weight loss.

Genitourinary: impotence; changes in libido; urinary retention.

Psychiatric: anxiety; irritability; restlessness; agitation; psychosis (more likely in people with Psychotic Disorders or Bipolar Disorder); mania and mixed states (more likely in people with Bipolar Disorder); substance abuse and dependence (more likely in people with a history of substance misuse).

Common side-effects of Amphetamine

Insomnia, headache, nervousness, restlessness, loss of appetite, nausea, dry mouth, constipation, diarrhea, weight loss.

Rare but serious side-effects of Amphetamine

  • heart attack and stroke, more likely in people with pre-existing cardiovascular disease
  • seizures, more likely in people with pre-existing seizure disorders.
  • rare reports of cardiomyopathy
  • sudden death has been reported in a few individuals with pre-existing cardiac structural abnormalities.

Amphetamine overdose

Restlessness, panic states, agitation, psychosis, tremor, fever, rapid respiration, nausea, vomiting, diarrhea, abdominal cramps, hyperreflexia, rhabdomyolysis, arrhythmias, hypertension or hypotension, circulatory collapse, seizures. Can lead to coma and death.

Amphetamine and pregnancy

There is insufficient data to know whether or not this medication is safe in human pregnancy, though animal studies have not found it to be harmful to the fetus at regular doses. It can be tried in pregnancy if the potential benefit justifies the potential risk to the fetus.

Medical Monitoring for Amphetamine

Blood pressure should be monitored regularly. Weight and height should be measured in children.

Drug Interactions with Amphetamine