Influence of the defective metabolism of sparteine on its pharmacokinetics.

Sparteine is metabolized by N1-oxidation, which in some subjects is defective. The defect has a pronounced effect on the kinetics of the drug. In nonmetabolisers elimination of sparteine proceeds entirely via renal excretion by a capacity-limited process, 99,9% of the dose being excreted as unchanged drug. In metabolisers the drug is mainly eliminated by metabolic degradation. Pronounced differences in beta-phase half-life and total plasma clearance were observed between metabolisers (156 min; 535 ml . min-1) and nonmetabolisers (409 min; 180 ml . min-1).