The disposition of the local anaesthetic, pentacaine, in rats and mice

The pharmacokinetics of pentacaine, a new local anaesthetic agent from the group of carbanilates, was investigated in the rat at a dose of 2 mg kg −1 i.v. and per os. A three‐compartment open model gave the best fit to the data. The model parameters are: t 1/2 99.0 ± 14.1 min, V ss 7411.1 ml kg −1 , Cl 77.9 ml min −1 kg −1 ; after oral administration t 1/2 ab 4.9 ± 1.9 min, bioavailability 59.1 per cent, and extent of absorption 79.3 per cent. Pentacaine is eliminated almost entirely by metabolism. The metabolites are excreted equally in the urine and faeces at a relatively slow rate. The pharmacokinetics of pentacaine was linear in the dose range 0.008–4 mg kg −1 . The whole‐body autoradiography in mice showed rapid transfer of 3 H radioactivity from the vessels to tissues and a markedly heterogenous disposition pattern in organs.