Pharmacokinetics of rizatriptan in healthy elderly subjects

Objective: Rizatriptan is a serotonin 5-HT1B/1D receptor agonist for acute treatment of migraine. Its pharmacokinetics were assessed in healthy elderl y males and females receiving a single 10 mg tablet oral dose. The pharmaco kinetic data (AUC(0-infinity) and C-max) for the elderly in this study were compared with historical data from previous studies for healthy young adul ts (n = 65). Methods: In a double-blind, parallel, placebo-controlled study , healthy elderly female and male subjects aged 65 or older (n = 8 each) re ceived a single oral dose of 10 mg rizatriptan. Plasma and urine concentrat ions of drug were determined by HPLC with tandem mass spectrometry detectio n at several collection time points or intervals starting at predose and po stdose over 24 h. Results: lin elderly subjects, the geometric mean values for AUC(0-infinity) 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%, re spectively. The AUC(0-infinity) and C-max of rizatriptan were similar in el derly 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 Cma, ratio was 0.89 with 90% confidence interval (0.72, 109), p > 0.2 5. 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 pharmac okinetics of rizatriptan do not appear to differ between male and female to a clinically Significant extent.