Pharmacokinetics of pancuronium in patients with normal and impaired renal function

Plasma concentration curves of patients with normal and impaired renal function are fitted to a tri-exponential function according to an open three compartment pharmacokinetic model. A detailed discussion of the relationship between theoretical distribution volumes, clinical pharmacodynamics and morphological or biochemical structures provides the basis for the concept of a central application and measuring compartment, a pharmacologically specific compartment and a non specific one. The distirbution of pancuronium from the application compartment to the specific compartment results in the onset of muscular paralysis. The recovery is governed by renal elimination of the unchanged drug as well as by its redistribution into the non specific compartment. In anuric patients the spontaneous recovery after 3--4 h is the effect of redistribution only. Neither metabolic degradation nor increased biliary elimination can sufficiently compensate for the lack of the renal pathway. The clinician should always keep in mind that after the recovery from pancuronium-induced muscular paralysis, both in patients with or without renal pathology, considerable residues of the active drug are stored at nonspecific and even specific receptor sites for many hours.