Pharmacokinetics of ranitidine and nizatidine in very elderly patients

Purpose Histamine H2-antagonists, ranitidine and nizatidine, are frequently used for the treatment of hyperacidity and peptic ulceration. Although these agents are mainly eliminated by renal route, the fraction of renal clearance of ranitidine (70%) was greater than that of nizatidine(60%). This study was undertaken to examine whether the pharmacokinetic profiles of ranitidine and nizatidine differed during a repeated dosing in very elderly patients (>80 years old). Methods Ranitidine (150mg) or nizatidine (150mg) was given twice a day in 10 female very elderly patients (mean CLcr 67 ml/min) for 14 days. This study was performed by a randomized, cross-over design with a wash-out period of 14 days. Pharmacokinetic profiles were determined after 1st (on day 1) and 27th (on day 14) dosings of each agent. Results The maximum plasma drug concentration (Cmax) and area under the plasma drug concentration-time curve (AUC) were significantly greater after 27th than after 1st dosings in the ranitidine, but not in the nizatidine trials. The accumulation of ranitidine in plasma tended to be greater than that of nizatidine. Conclusion These results suggest that nizatidine is more safe for the repeated treatment in the very elderly patients. Clinical Pharmacology & Therapeutics (2004) 75, P10–P10; doi: 10.1016/j.clpt.2003.11.035