Pharmacokinetics of ranitidine during hemodiafiltration

Introduction

Ranitidine, a histamine-2 receptor antagonist, is frequently used in intensive care patients requiring stress ulcer prophylaxis. Continuous venovenous hemodiafiltration (CVVHDF) is an important extracorporeal renal replacement therapy in critically ill patients suffering from multiple organ failure. This study investigates the pharmacokinetics of ranitidine in anuric critically ill patients undergoing CVVHDF.

Methods

Ranitidine 50 mg was administered intravenously in five intensive care patients with acute renal failure undergoing CVVHDF who required stress ulcer prophylaxis. The concentration of ranitidine in serum and ultradiafiltrate was determined by high-performance liquid chromatography.

Results

The mean peak serum level of ranitidine was 1.95 ± 0.55 mg/l. The mean trough serum level was 0.50 ± 0.29 mg/l. The mean AUC 0–8 was 5.47 ± 2.83 mg.hour/l. The volume of distribution and the half-life were 73.72 ± 33.25 l and 14.54 ± 9.82 hour, respectively. Total clearance and hemodiafiltration clearance were 5.05 ± 3.92 l/hour and 1.28 ± 0.39 l/hour, respectively.

Conclusion

Pharmacokinetics of a single dose of ranitidine in anuric critically ill patients undergoing CVVHDF is comparable with reported results in healthy volunteers. No dose adaptation of ranitidine therefore seems necessary in critically ill patients undergoing CVVHDF. However, prior to translation of these findings to the clinical arena, multiple dose studies are required.