Amphetamines seem to exert an anorexogenic effect. As a result of these effects, weight decreases. This agent is useful as an adjunct to decreased caloric intake in the treatment of obesity. The anorexogenic effect is postulated to be secondary to CNS stimulation and a decrease in the acuity of smell and taste. Amphetamines do not seem to alter the basal metabolic rate or nitrogen excretion.
Metabolism occurs in the liver.
Excretion is via the kidney and is affected by pH, with more rapid excretion occurring in acidic urine and slower excretion occurring in alkaline urine. Dextroamphetamine is contraindicated in patients with advanced arteriosclerosis, symptomatic cardiac disease, glaucoma, hypertension, hyperthyroidism, or Tourette's syndrome because it can exacerbate these conditions. Dextroamphetamine should not be used as an anorexic agent in children under 12. Dextroamphetamine should not be used within 2 weeks following discontinuation of a monoamine oxidase inhibitor because dextroamphetamine metabolism can be slowed, resulting in increased effects. Urinary acidifiers, such as ammonium chloride, reduce the tubular reabsorption of dextroamphetamine.