© Priory Lodge Education Limited, 1996.
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Potential for abuse

Abuse of anticholinergic drugs for pleasurable purposes has been recognised and anticholinergic drugs have been reported to be drugs of abuse by patients on prescription as well as by those dependent on other agents (Smith, 1980; Pullen et al, 1984). Amongst psychiatric patients, although most abusers of anticholinergic drugs are found to be patients receiving neuroleptics to control symptoms of schizophrenia or affective disorders, patients with antisocial or borderline personality disorder have also been reported to use anticholinergic drugs as drugs of abuse (Crawshaw & Mullen, 1984). Increased abuse of anticholinergic drugs is thought to be related to unavailability of other commonly abused substances (Kaminer et al, 1982) and some abusers may use anticholinergic drugs to potentiate the effects of other psychoactive substances.

Many schizophrenic patients have been observed to prefer anticholinergic drugs to neuroleptic drugs (Gelenberg, 1984) which is thought to be related to stimulant or euphorogenic properties of anticholinergics. It is thought that up to 17% of patients on prescription of anticholinergic drugs will misuse or abuse them at some time (Wells et al, 1989). Anticholinergic drugs have also been found to have antidepressant, stimulant, euphoriant and hallucinogenic effects (Bolin, 1960; Dilsaver, 1988).

Patients with schizophrenia have been known to increase the dose of anticholinergic drugs. It is thought that schizophrenic patients with negative symptoms become less socially withdrawn and have less affective blunting when using anticholinergic medication (Tandon et al, 1988). This is thought to be the primary reason for misuse of anticholinergic drugs in this patient group.

Abuse of all anticholinergic drugs has been reported in the literature (Pullen et al, 1984), however, abuse of trihexyphenydyl is thought to be most common (Dilsaver, 1988). Oral ingestion is the commonest route of administration although intravenous injections and even smoking the drug often mixed with tobacco (Rouchell, 1977) has been reported.