Fluoxetine: prescribing guidelines for the newest antidepressant.

Fluoxetine is an antidepressant drug with a unique chemical configuration which enhances serotoninergic transmission by inhibiting serotonin uptake. The chronic presence of serotonin in the synaptic cleft reduces postsynaptic receptors, a postulated explanation for its antidepressant efficacy. Comparative studies show that the therapeutic effectiveness of fluoxetine is equal to that of imipramine, amitriptyline, and doxepin. A 20 mg morning dose alleviates most depressions. The long half-life of one to three days for the parent compound and seven to 15 days for the active metabolite, desmethylfluoxetine, is largely unaffected by age or renal impairment. Nausea, nervousness, insomnia, and headache are the most common side effects. Therapeutic doses do not affect cardiac conduction or cause orthostasis. A primary benefit of this drug is its significant relative safety in overdoses as compared to other antidepressants.