Pharmacokinetic study of esomeprazole in the elderly

Objective: Esomeprazole is the first proton pump inhibitor to be developed as an optical isomer for the treatment of patients with acid-related diseases. The aim of this study was to examine the pharmacokinetics and tolerability of esomeprazole in the elderly, relative to middle-aged patients with gastro-oesophageal reflux disease (GORD). Design: Nonblinded single-centre pharmacokinetic study with historical control group. Patients and Participants: 14 healthy elderly volunteers [mean age 74 (range 71 to 80) years]. Methods: Participants received treatment with esomeprazole 40mg once daily for 5 days, with 24-hour blood sampling on days 1 and 5. The total area under the plasma concentration-time curve (AUC(infinity)), maximum plasma drug concentration (C-max), terminal elimination half-life (t1/2z) and time to C-max (t(max)) were determined for the parent drug and its hydroxy and sulphone metabolites. AUC(infinity) and C-max data were compared with those in an historical group of 36 middle-aged patients [mean age 45 (range 29 to 58) years] with GORD, treated with an identical dosage of esomeprazole for 5 days. Results: A total of 13 volunteers completed the study. On day 5, the mean plasma AUG, of esomeprazole was 16.0 mu mol (.) h/L, C-max was 5.6 mu mol/L, t(max) was 1.5 hours and t1/2z was 17 hours. The AUG(infinity) and C-max values for the parent drug were 2- and 1.5-fold higher on day 5 compared with day 1. AUC(infinity) and C-max values for the sulphone metabolite increased to a slightly greater extent, and Values for the hydroxy metabolite were unchanged. Ratios of the AUC(infinity) and C-max values between elderly volunteers and patients with GORD were 1.25 [95% confidence interval (CI) 0.94, 1.67] and 1.18 (0.91, 1.52), respectively. Esomeprazole was well tolerated and there were no safety concerns. Conclusions: The AUC(infinity) and Cmax values in the elderly were not significantly different from those obtained in a group of middle-aged patients. The difference for AUC(infinity) was 25% (95% CI-6% to +67%). Esomeprazole has a wide therapeutic window and our results do not indicate that dosage adjustment should be necessary in the elderly.