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Phencyclidine and phenylcyclohexene disposition after smoking phencyclidine
Clinical Pharmacology and Therapeutics
|May 1, 1982
Summary
Smokers absorbed most phencyclidine hydrochloride (PCP) from parsley cigarettes, with measurable plasma levels of PCP and its pyrolysis product, 1-phenylcyclohexene (PC). The drug
Area of Science:
- Pharmacology
- Toxicology
- Drug Metabolism
Background:
- Phencyclidine hydrochloride (PCP) is a drug with known psychoactive effects.
- Understanding PCP absorption and metabolism after smoking is crucial for clinical and forensic toxicology.
Purpose of the Study:
- To quantify the absorption and disposition of PCP and its pyrolysis product, 1-phenylcyclohexene (PC), following inhalation from smoked parsley cigarettes.
Main Methods:
- Five male subjects smoked [3H]-PCP.HCl-containing parsley cigarettes.
- Plasma and urine samples were analyzed for PCP, PC, and their metabolites.
- Pharmacokinetic parameters, including half-life and metabolite ratios, were determined.
Main Results:
- Inhaled dose absorption of PCP was high (estimated >69%).
- PCP exhibited a mean half-life of 24 hours, similar to oral/IV routes.
- PC was detected in plasma at lower concentrations and had a shorter half-life than PCP.
Conclusions:
- Smoking PCP results in significant systemic absorption.
- PCP disposition after smoking is comparable to other administration routes.
- PC is a detectable pyrolysis product but is rapidly cleared and minimally excreted unmetabolized.