Disposition of Phencyclidine after Intramuscular Administration

Abstract

The disposition of radioactive phencyclidine (PCP) in various rat tissues, after single or repeated intramuscular injections for 23 days, have been investigated. Peak levels of radioactivity appeared 45–90 min after a single administration. The pancreas, salivary glands and mesenteric fat contained 4 to 6-fold higher radioactivity than brain, muscles, tendons, and bones. After repeated ³H-PCP injections, radioactivity levels showed a similar pattern as to that of the peak levels after a single administration, but at notably higher values. On the other hand, the percentage of depletion, within 48 h after the final injection, was the highest in the pancreas, salivary glands and mesenteric fat. It is possible that despite the low retention capacity of PCP radioactivity per unit weight of muscle, tendon and bone, they may be considered important reservoirs for either PCP, or its metabolites or both because of their large relative mass in the body.