Kinetics of ketamine and its metabolites in rabbits with normal and impaired renal function

The plasma levels of ketamine, an anaesthetic, and its metabolites were studied in 10 rabbits with normal renal function and in 9 rabbits with varying degrees of experimentally induced renal impairment. All the animals received a single bolus type i.v. dose of 10 mg/kg of the drug. The results obtained reveal an apparent inhibition of the biotransformation of ketamine in rabbits with renal impairment in which the drug is accumulated. The plasma half-life of ketamine ranged from 0.74 h in rabbits with normal renal function to 2.6 h in the animals with severe renal impairment. The plasma levels of norketamine (metabolite I) did not alter significantly in states of renal impairment. However, the kinetics of the other metabolite (II), dehydronorketamine, did change significantly in renal impairment, due to its high renal excretion capacity.