Tricyclic antidepressants
In addition to blocking reuptake of NE and 5HT, pharmacodynamic actions of the tricyclic antidepressants include block of peripheral adrenergic and muscarinic receptors--the former resulting in postural hypotension and the latter, via mydriasis, exacerbating glaucoma. TCAs block the uptake of guanethidine into sympathetic nerve endings, decreasing its antihypertensive effects, and they may cause arrhythmias in overdose. They have no effect on the absorption of levodopa.
increase the antihypertensive effect of guanethidine
have anticonvulsant activity
should not be used in patients with glaucoma
may increase oral absorption of levodopa
C.N.S