Pharmacologic response to pentobarbital in passively immunized mice

Rabbits were actively immunized using a barbiturate--BGG conjugate as the immunogen. The antiserum obtained from actively immunized rabbits was administered intravenously to mice to accomplish passive immunization. The antibody binding capacity for 3H-phenobarbital was shown to be sustained in passively immunized mice for periods of up to three weeks. Serum levels of 3H-phenobarbital in passively immunized mice and control mice were compared following drug administration and found to be altered in the antibody-containing mice. There was a 4-fold higher amount of 3H-phenobarbital present in the serum of passively immunized mice compared to control animals. The higher barbiturate levels were due to binding of 3H-phenobarbital to globulin fraction of serum in passively immunized mice. Additionally, decreased pentobarbital-induced ataxia was demonstrated in passively immunized mice. The decreased responsiveness was selective for barbiturates in passively immunized mice and did not modify the ataxia produced in these animals by another depressant agent, ethanol.