Pharmacokinetics of ranitidine in patients undergoing haemofiltration

The pharmacokinetics of ranitidine was investigated in 11 patients with acute or end stage renal failure during haemofiltration. Each patient received 50 mg ranitidine i.v. The mean distribution and elimination half lives were 0.13 and 2.57 h, respectively. The total body clearance (CL) and volume of distribution (Vz) were 298 ml.min-1 (5.19 ml.min-1.kg-1) and 1.08 l.kg-1, respectively. About 17.1% of the administered dose was removed by haemofiltration (in approximately 20 l filtrate). Five of the patients still had some urine output and they excreted 0.1 to 11.8% of the dose in urine in 24 h. The haemofiltration clearance was 66.9 ml.min-1 at a filtrate flow rate of 86 ml.min-1, corresponding to a mean sieving coefficient of 0.78 (n = 6). As plasma concentrations were still in an effective range after haemofiltration, dose supplementation is not recommended.