Single and multiple oral dose fluvoxamine kinetics in young and elderly subjects

The pharmacokinetics of fluvoxamine maleate was studied in two separate studies in healthy young and elderly subjects. In a single and multiple oral dose administration study, six healthy young subjects received an initial 50 mg oral dose followed by 50 mg tablets every 12 h for 28 days. In a second study, 13 elderly subjects received 50 mg tablets every 12 h for 28 days. Fluvoxamine peak plasma concentrations were reached in approximately 5-6 h following oral administration of single and multiple 50 mg doses to healthy young and elderly volunteers. The area under the curve (AUC) of fluvoxamine tended to be larger following multiple (873 ng.h/ml) as compared to single-dose administration (652 ng.h/ml). Also the terminal half-life after chronic dosing (22 +/- 6 h) tended to be longer than after single dosing. Steady-state plasma levels were obtained within 10 days' administration. The pharmacokinetics of fluvoxamine in elderly healthy subjects were no different from those recorded in young subjects. These results suggest that it is not necessary to adjust the dosage of fluvoxamine in elderly depressed patients, on the basis of pharmacokinetic arguments. Independent of the age group, approximately 3% of a dose was recovered as unchanged drug in the urine.