MEDizzy - A 30-year-old man complained of dry mouth, constipation, and

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NEUROLEPTIC DRUGS

A 30-year-old man complained of dry mouth, constipation, and blurred vision while reading the newspaper. The man, recently diagnosed with a schizoid disorder, had started treatment with clozapine 2 weeks previously. Blockade of which of the following receptors most likely mediated the adverse effects reported by the patient?

ExplanationThe correct answer is D. Some atypical neuroleptics such as clozapine have significant blocking activity on muscarinic receptors. The patient’s symptoms are classic antimuscarinic effects due to clozapine. Blockade of cholinergic M3 receptors in the salivary glands causes dry mouth, in the intestinal system causes a decrease in peristalsis, and in the ciliary muscles causes a loss of accommodation for near vision.