vi medicine informatics




The most likely class of antidepressants to cause orthostatic hypotension is the tricyclic antidepressants (TCAs) (eg, amitriptyline). Although TCAs function via blockage of norepinephrine and 5-HT reuptake, they interact with other receptors as well, producing important side effects, such as TCA blockade of α1-receptors, resulting in orthostatic hypotension. Activation of α1-receptors in the vascular smooth muscle causes vasoconstriction. Thus, blockage of α1-receptors can lead to reduced arteriolar resistance and postural hypotension. α1-Receptors are of the Gq class, and blockage of α1-receptors will lead to a decrease in phospholipase C and calcium release. TCAs can also produce anticholinergic side effects (tachycardia, urinary retention, dry mouth) via interaction with muscarinic receptors and sedation via interaction with the H1-receptor. As mentioned above, the side effect profile of TCAs is a cardinal reason why TCAs are avoided in the elderly.

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