Overview Nicotinic antagonist hexamethonium first drug developed for hypertension treatment mecamylamine CNS penetration therefore can result in sedation, tremor, and choreiform movements trimethaphan short-acting, IV-administered Clinical use block nicotinic receptors at sympathetic and parasympathetic autonomic ganglia have low selectivity and wide array of effects limiting its use used in experimental models to prevent vagal reflex responses to changes in blood pressure such as to prevent reflex bradycardia caused by NE Toxicity severe orthostatic hypotension cycloplegia with loss of accommodation constipation sexual dysfunction: may prevent erection and ejaculation urinary retention in men with prostatic hyperplasia