Hypotension alpha-blocking drugs causing

D. Toxicity and Interactions Sedation is common, especially with diphenhydramine, doxylamine, and promethazine. It is much less common with second-generation agents, which do not enter the CNS readily. Antimuscarinic effects such as dry mouth and blurred vision occur with some first-generation drugs in some patients. Alpha-blocking actions may cause orthostatic hypotension. 

Answer C. Orthostatic hypotension occurs with both tricyclic antidepressants and phe-nothiazines because both types of drug can block alpha adrenergic receptors in venous beds. Their ability to block M receptors leads to xerostomia (not salivation) and mydriasis (not miosis). THcyclics and phenothiazines also share a common tendency to decrease seizure threshold and cause weight gain (not loss). 

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