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Objective: Rizatriptan is a serotonin 5-HT 1B/1D receptor agonist for acute treatment of migraine. Its pharmacokinetics were assessed in healthy elderly males and females receiving a single 10 mg tablet oral dose. The pharmacokinetic data (AUC 0- ∞and C max ) for the elderly in this study were compared with historical data from previous studies for healthy young adults (n = 65). Methods: In a double-blind, parallel, placebo-controlled study, healthy elderly female and male subjects aged 65 or older (n = 8 each) received a single oral dose of 10 mg rizatriptan. Plasma and urine concentrations of drug were determined by HPLC with tandem mass spectrometry detection at several collection time points or intervals starting at predose and postdose over 24 h. Results: In elderly subjects, the geometric mean values for AUC 0- ∞ and C max were 77. 7 ng/h/ml and 21.9 ng/ml; the average values for t max , half-life (t 1/2 ), renal clearance (Cl r ), and percent urinary excretion of dose (U e ) were 1.2 h, 1.8 h, 197 ml/min and 9.3%, respectively. The AUC 0- ∞ and C max of rizatriptan were similar in elderly and young subjects. The geometric mean AUC ratio of elderly to young was 0.96 with 90% confidence interval (0.83, 1.11), p > 0.25. The geometric mean C max ratio was 0.89 with 90% confidence interval (0.72, 109), p > 0.25. No significant pharmacokinetic differences were observed between elderly males and females. Conclusions: The plasma pharmacokinetics of rizatriptan appear to be similar in the elderly and young. In the elderly, the pharmacokinetics of rizatriptan do not appear to differ between male and female to a clinically significant extent.