Pharmacokinetics of morphine in two children before and after liver transplantation.

Plasma morphine, morphine-3-glucuronide and morphine-6-glucuronide concentrations were measured (HPLC) in two children immediately before orthotopic liver transplantation and in the postoperative period. Both of the patients had end-stage hepatic failure, but one also had impaired renal function before operation and was oliguric during and after surgery. Both patients metabolized morphine rapidly, but in the patient with renal failure, the metabolites appeared to accumulate. Morphine has active metabolic products and the accumulation of these in patients with impaired renal function may lead to a clinically observable prolongation of its effect.