Trihexyphenidyl toxicity

Trihexyphenidyl (Artane) and benztropine (Cogentin) are prescription drugs used in the treatment both of Parkinson s disease and the extrapyramidal side effects produced by neuroleptic medication. They are occasionally abused for their mind-altering properties, which occur at toxic doses (Perry et al. 1978). Abusers often try to obtain these drugs by false representation of extrapyramidal symptoms, which are claimed to result from the use of phenothi-azines or other neuroleptics (Rubinstein 1978). 

Ricaurte GA, McCann UD, Szabo Z, et al Toxicodynamics and long-term toxicity of the recreational drug 3,4-methylenedioxy-methamphetamine (MDMA, Ecstasy ). Toxicol Lett 112-113 143-146, 2000 Robinson TN, Killen JD, Taylor CB, et al Perspectives on adolescent substance use a defined population study. JAMA 258 2072-2076, 1987 Rubinstein JS Abuse of antiparkinson drugs feigning of extrapyramidal symptoms to obtain trihexyphenidyl. JAMA 239 2365, 1978 Rumack BH (ed) LSD, in Poisindex, Vol 54. Denver, CO, Micromedex, 1987 Rusyniak DE, Banks ML, Mills EM, et al Dantrolene use in 3,4-methylenedioxymethamphetamine ( ecstasy )-medicated hyperthermia (letter). Anesthesiology 10 263, 2004... 

Digoxin (cardiac glycoside) and trihexyphenidyl (antimuscarinic drug) must be used with caution in elderly patients. Low doses are recommended in elderly patients to avoid toxicity. Lactulose may be safely administered to elderly patients with constipation. 

Trihexyphenidyl has been misused by drug addicts to produce elation or reheve depression. One patient who took 300 mg with suicidal intent survived the resulting toxic psychosis (4). 

Answer C. Muscarinic receptor antagonists such as benztropine, trihexyphenidyl, and diphenhydramine are used to manage the reversible extrapyramidal dysfunction (e.g., pseu-do-Parkinsonism) that results from treatment with drugs that block DA receptors in the striatum. Drugs that activate DA receptors, although theoretically possible, require doses that are toxic and exacerbate psychoses. Because the actions of DA in the striatum lead to... 

In a double-blind study 3 patients given a phenothiazine and benzatropine for the parkinsonian adverse effects, developed an intermittent toxic confusional state (marked disturbance of short-term memory, impaired attention, disorientation, anxiety, visual and auditory hallucinations) with peripheral antimusearinies signs. Similar reactions occurred in 3 elderly patients given imipramine or desipramine, with trihexyphenidyl, and in another man given chlorpromazine, benzatropine and doxepin. ... 

---