Pharmacokinetics of fluoxetine in elderly men and women.

Fluoxetine is widely prescribed as an antidepressant for geriatric patients. Despite a large scientific literature describing its efficacy and safety, there are few published data describing the pharmacokinetics of fluoxetine in the elderly. Given the common practice of polypharmacy in this population, additional pharmacokinetic information in elderly men and women is needed so that physicians can better assess potential drug-drug interactions. Twenty-five subjects, men and women between ages 65 and 83, received 20 mg of fluoxetine for 1 week followed by 40 mg for 5 weeks. Serum fluoxetine levels were measured during the period of drug administration and for 8 weeks after. The plasma concentration of fluoxetine and norfluoxetine in our subjects was higher than previously reported in the literature. Elderly women had a significantly higher serum level of norfluoxetine than men. The terminal half-life of norfluoxetine was longer in patients over age 75; elderly women had a significantly slower rate of norfluoxetine elimination than similarly aged men. Copyright 2006 S. Karger AG, Basel.