Pharmacokinetics and pharmacodynamics of pipecuronium in patients with cirrhosis.

Abstract

To determine the effect of liver cirrhosis on the pharmacokinetics and pharmacodynamics of pipecuronium, the authors administered 100 micrograms/kg of pipecuronium intravenously to eight patients with liver cirrhosis and eight patients with normal liver and renal function undergoing elective abdominal surgery. All patients were anesthetized with thiopental (5-7 mg/kg), nitrous oxide (50-70% in oxygen), and fentanyl in repeated doses (2 micrograms/kg). Plasma concentrations of pipecuronium were determined by high-pressure liquid chromatography. A two-compartment open model was used for pharmacokinetic analysis. Thumb-elicited mechanical response to single-twitch ulnar nerve stimulation was also measured. Total plasma clearance did not differ between controls (2.96 +/- 1.05 mL.min-1.kg-1, mean +/- SD) and cirrhotics (2.61 +/- 1.16 mL.min-1.kg-1). Terminal elimination half-life was 111 +/- 46 min in controls and 143 +/- 25 min in cirrhotics. The total apparent volume of distribution at steady state did not differ between controls (350 +/- 81 mL/kg) and cirrhotics (452 +/- 222 mL/kg). The volume of the central compartment was not different between the two groups. The onset of neuromuscular blocking effect was longer in cirrhotics (233 +/- 112 s) (P < 0.05) than in controls (170 +/- 33 s). The clinical duration (injection until single twitch returned to 25%) was similar between the two groups: 167 +/- 41 min in controls and 165 +/- 48 min in cirrhotics. The authors conclude that hepatic insufficiency due to cirrhosis does not alter the pharmacokinetics and pharmacodynamics of pipecuronium (100 micrograms/kg).