Parkinsonism from haloperidol

Circunstantial evidence directly implicating dopamine in the pathogenesis of duodenal ulcer in man is the unusual incidence of peptic ulcer disease in dopamine-deficient disorders. From purely descriptive clinical and epidemiologic studies we know that patients with Parkinson s disease, before the introduction of dopamine therapy, had an excess of ulcer disease (72). One report even comments on the curiosity that after initiation of L-DOPA administration the ulcer symptoms have virtually disappeared (72 ). On the other hand, less clearly, schizophrenia which is associated with dopamine excess and/or receptor hyperactivity is accompanied by virtual lack, or decreased prevalence, of peptic ulcer (73-76). Schizophrenia associated with ulcer disease has been viewed as a reportable curiosity in medical literature (75). At present, possibly because of the widespread therapeutic application of neuroleptics, the lack of peptic ulcer disease in schizophrenics is less striking than in the past. On the other hand, we recently observed in our autopsy series perforated duodenal ulcers in two schizophrenic patients who had been on large doses of haloperidol therapy (Szabo, unpublished observation). Thus, even in man, dopamine may indeed be implicated in the pathogenesis of duodenal ulcer disease. 

D2-receptor activation gives Gai-mediated inhibition of adenylate cyclase (decreasing cAMP) and these receptors are involved in schizophrenia and Parkinson s disease and in control of motor function, cardiovascular function and behaviour by the CNS. The well-known antipsychotics chlorpromazine and haloperidol are D2-R antagonists. A number of hallucinogenic indole alkaloids from ergot-infected grasses and cereals are D2-R agonists (Table 5.4). 

Biperiden, a substance with a parasympatholytic effect, is used in the treatment of Parkinson s disease. It is available on prescription only, the therapeutic dose being 2-12 mg/day. Apart from this use, biperiden is also prescribed for the treatment of extrapyramidal motor disturbances caused by the use of highly active neuroleptic drugs (haloperidol, benperidol etc.). The consumption of 20-30 mg biperiden produces a euphoric effect which can occasionally culminate in a reversible psychosis. 

A 49-year-old woman was taking amantadine 200 mg daily, haloperidol 5 mg daily and flurazepam 30 mg at night was given phenelzine 15 mg twice daily for depression. Within 72 hours her blood pressure rose from 140/90 to 160/110 mmHg. The phenelzine was withdrawn, and 24 hours later, the amantadine and haloperidol were withdrawn. The blood pressure remained elevated for a further 72 hours. In contrast, a woman is reported to have been successfully and uneventfully treated with amantadine 200 mg daily for Parkinson s disease and phenelzine 45 mg daily for depression. ... 

Possibly. Sufferers from Tourette s syndrome are helped by using a nicotine patch to stimulate the haloperidol medicine they are taking. It is also believed that smokers are less likely to contract Parkinson s disease, but smoking is a rather drastic way to get those benefits. 

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