Phencyclidine (PCP, Angel Dust) is a cheap and popular drug often concentrated in selected socioeconomic groups. PCP may be characterized as a hallucinogenic drug due to the wide range of bizarre behaviors associated with individuals under the influence. It was originally used as a veterinary tranquilizer and has had some human experimentation, but the bizarre recovery room effects made it useless. PCP has been illicitly used since the 1960’s, but not a widely abused drug until the 1980’s when it was placed on cigarettes (Sherms), and smoked. Smoking allows the user to rapidly and accurately titrate their dose. The effects of a drug ingested by smoking are quickly felt since it is rapidly absorbed by the lungs into the bloodstream and circulated to the site of action in the brain. Thus, smoking allows the user a rapid feedback on how “high” they are getting. Phencyclidine is easily manufactured from relatively common chemical precursors, is relatively potent, and long lasting. These factors combined make it a frequently abused illicit drug.
Phencyclidine is rapidly absorbed from the lung and easily crosses the blood/brain barrier. In an average size (150 lb.) individual, each absorbed milligram (mg) will produce approximately 10 ng/ml concentration in the blood. Symptomatic blood concentrations range from about 4 ng/ml to 100 ng/ml. Symptoms progress from barely observable/perceptible at the lower end to comatose/catatonic at 100 ng/ml. Higher concentrations have been recorded. Observable symptoms include “ether” breath (or “solvent” breath), nystagmus (vertical and horizontal) movements of the eye, “moon walk”, and a diverse variety of behavior including hallucinations, catatonic rigidity, “superhuman” strength, lack of stimulus to pain, time distortions, and lack of memory and events while “stoned”.
Phencyclidine has several analogues and precursors. Most are illegal. Some labratories screen for phencyclidine by immunoassay and confirms by gas chromatography/mass spectrometry (GC/MS).
Cutoff and Detection Post Dose
The immunoassay technique used to detect PCP in urine has a cutoff level of 25 ng/ml. PCP is cleared from the bloodstream with a relatively long half life of 7-11 hours. Because it is a lipid (fat) soluble drug, detection in the urine is possible up to 48 hours or longer post dose. Blood levels correspond much better than urine to behavioral effects, i.e. being under the influence, but urine is a better screening fluid since drugs are concentrated for elimination. Confirmation levels on GC/MS is 25 ng/ml.