<prompt> Dryness of mouth caused by antipsychotic drug is caused by blockade of:Muscarinic ACh receptorsGABA receptorsSerotonergic receptorsDopaminergic receptors  <response>: Xerostomia, commonly known as dry mouth, is a repoed side effect of 1,800 drugs from 80 classes. ... Among all repoed side effects of antidepressants andantipsychotics, dry mouth often is the most prevalent complaint. For example, in a study of 5 antidepressants 35 to 46 of patients repoed dry mouth. Ref KD Tripati 8th ed. 