special subjects
Ketamine and Phencyclidine (PCP)
Symptoms and Signs ofKetamineor PCP Use
Intoxication, characterized by a giddy euphoria, occurs with lower doses; euphoria is often followed by bursts of anxiety or mood lability. Overdose causes a withdrawn state of depersonalization and disassociation; when doses are higher, disassociation can become severe and response to external stimuli is impaired, with combativeness, ataxia, dysarthria, muscular hypertonicity, nystagmus, hyperreflexia, and myoclonic jerks. With very high doses, acidosis, hyperthermia, tachycardia, severe hypertension, seizures, and coma may occur; deaths are unusual. Although rare,ketaminemay induce brief or recurrent laryngospasm even at a therapeutic dose. Acute effects generally fade rapidly and many patients regain normal consciousness in 45 minutes to several hours. Emergence reaction is an adverse reaction to PCP andketamineuse seen during the recovery phase. It manifests with bizarre behavior, psychosis, confusion, hallucinations, vivid dreams, or the sensation of floating. Some symptoms may last for weeks. Development oftolerance and dependence to PCPhave been seen in animal studies. Psychologic dependence onketaminehas been reported. Some patients may developwithdrawal symptoms fromketaminesuch as anxiety, sweating, and palpitations. Lower urinary tract symptoms such as dysuria, urinary frequency, and hematuria have been reported among long-termketamineusers. Frequent use ofketaminemay cause long-term memory impairment. 