Effect of chronic pentobarbital treatment on blood-cerebrospinal fluid kinetics

Cats were made tolerant and physically dependent by twice daily equieffective anesthetic dosing with sodium pentobarbital intragastrically for 5 weeks. Serial blood and CSF samples were simultaneously collected on day 1 and day 35 and analyzed for pentobarbital by a gas chromatographic method. Pentobarbital penetration into CSF was rapid and unchanged by chronic treatment. The concentration in blood and CSF increased significantly with chronic treatment; however, the relative CSF/blood concentration ratios were unchanged.