Intravenous self-administration of phencyclidine and related compounds in the dog.

Beagle dogs were given access to response-contingent i.v. infusions of phenycyclidine (PCP) and eight related compound. The infusions of phencyclidine (PCP) and eight related compounds. The infusions were available during short (1- or 4-hr) daily sessions when each pedal-press produced a drug or vehicle infusion. All nine compounds maintained consistent, dose-related pedal-pressing at rates considerably above those maintained by their respective vehicles. For each compound there was an inverted, U-shaped relationship between dose (microgram per kilogram per infusion) and number of infusions self-administered per session. By comparing the descending portions of the dose-response curves obtained with each compound, estimates of their relative potencies to maintain equal rates of drug-taking behavior were calculated. The thiophene analog was the most potent compound, followed in order by PCP, the N-ethyl, pyrrolidino, 4-methyl and N-propyl analogs, the two monohydroxylated metabolites and ketamine. The rank-order of these potency estimates is similar to those obtained with a variety of other animal paradigms used to assess the effects of PCP and its analogs. All nine compounds produced varying degrees of ataxia, vocalizations and salivation in the dogs. The results suggest that several compounds related to PCP may have an abuse potential like that of PCP.