Orthostatic hypotension alpha-blocking drugs causing

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). 

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. 

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