Pharmacokinetics and brain entry of alaptide, a novel nootropic agent, in mice, rats and rabbits.

Pharmacokinetics of a novel nootropic agent, alaptide, have been examined in plasma and brain of mice, rats and rabbits following an intravenous dose (1 mg kg-1). First-order equilibration rate constants between plasma and brain (kBO) were calculated by a two-compartment model with a linked compartment (brain). Brain alaptide equilibrates rapidly with the central compartment in mice and rats due to the high kBO/beta ratio. In rabbits the equilibration is much slower (kBO/beta approximately 1). Partition coefficients between brain and plasma calculated from areas under the brain and plasma concentration-time curves, are 0.479, 0.549 and 0.864, in mice, rats and rabbits, respectively.