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 It is thought that schizophrenic patients with negative symptoms become less socially withdrawn and have less affective blunting when using anticholinergic medication (Tandon et al, 1988).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.