Dexamphetamine

• a stereoisomer of amphetamine (amfetamine) - has greater stimulant properties than amphetamine (amfetamine)
• licensed indications include for treating childhood hyperactivity where non-pharmacological measures have proved insufficient - there is evidence that treatment with dexamfetamine (or methylphenidate) relieves the symptoms of severe hyperactivity in children, at least, in the short-term (1)
• dexamfetamine is also used in the treatment of narcolepsy
  • however there are few published controlled trials assessing dexamfetamine in patients with narcolepsy (2)
    • in one double-blind crossover trial, dexamfetamine (30mg daily for 4 weeks) roughly halved "sleep attacks" (from 4.4 to 2.2 per day, p<0.01)
• dexamfetamine can cause dependence and tolerance (and in the UK, it is classified as a Controlled Drug), and so some doctors and patients may be reluctant to use it (2)
• adverse effects include:
  • emotional lability, insomnia, reduced appetite
  • there have been reports of growth retardation with long-term use - this effect can be reduced by using drug-free periods; also effect does not appear to affect final adult weight and height
  • rare effects - seizures, compulsive behaviours, psychotic reactions, persistent dysphoria, lack of spontaneity
• dexamfetamine is contraindicated in patients with moderate to severe hypertension.

The Summary of Product Characteristics must be consulted before prescribing this drug.

Reference:

1. Drug and Therapeutics Bulletin 2001; 39(7):52-54.
2. Drug and Therapeutics Bulletin 2004; 42(7):52-56.