Abstract
Effect of high dose administration of pentobarbital and phenylbutazone on the plasma biologic half lives were determined. The remarkable effect on the plasma biologic half life was seen in the pentobarbital administration especially in the mouse, rabbit, cat, dog and monkey. In the case of phenylbutazone administration, however, the prolongation of the half life in the high dose group was seen only in the dog. The liver microsomal pentobarbital and phenylbutazone metabolizing enzyme activities were, in general, in agreement with the plasma biologic half lives.
