Alfentanil kinetics in renal insufficiency

Alfentanil 100 micrograms/kg was administered as an i.v. bolus to 9 patients with severe chronic renal dysfunction (creatinine clearance 1.0 +/- 1.2 ml/min) requiring regular haemodialysis. Plasma alfentanil concentrations were measured by a specific radioimmunoassay. Individual plasma concentration-time curves were fitted to a two-compartment open model. Mean distribution and elimination half-lives were 3.7 min and 58 min, respectively. The apparent volumes of distribution of the central compartment and the total volume of distribution at steady-state were 91 ml/kg and 304 ml/kg, respectively. Alfentanil plasma clearance was 5.3 +/- 2.5 ml/min/kg. All the patients tolerated alfentanil well and no side-effects nor delayed recovery were observed.