Phencyclidine is central nervous system (CNS) depressants. Phencyclidine, also known as PCP, is a hallucinogen that was first marketed as a surgical anesthetic in the 1950's. It was removed from the market because patients receiving it became delirious and experienced hallucinations. Phencyclidine is used in powder, capsule, and tablet form. The powder is either snorted or smoked after mixing it with marijuana or vegetable matter. Phencyclidine is most commonly administered by inhalation but can be used intravenously, intranasally, and orally. After low doses, the user thinks and acts swiftly and experiences mood swings from euphoria to depression. Self-injurious behavior is one of the devastating effects of Phencyclidine. Phencyclidine is excreted in the urine as unchanged drug (4% to 19%) and conjugated metabolites (25% to 30%) with a half-life of about 12 hours. This test detects the presence of phencyclidine in human urine specimens, qualitatively.