Mecamylamin

Mecamylamine is a non-depolarizing ganglion-blocking agent that acts as a competitive antagonist at nicotinic acetylcholine receptors in autonomic ganglia (the Nn subtype). By preventing transmission at both sympathetic and parasympathetic ganglia, it reduces autonomic outflow and can lower blood pressure. Historically, it was used to treat severe or resistant hypertension, particularly before safer antihypertensive drugs became available. Because it blocks autonomic reflexes, its use can cause orthostatic hypotension, tachycardia, dizziness, fatigue, and various central nervous system effects, including sedation and cognitive changes, since it is lipophilic enough to cross the blood–brain barrier.

Mecamylamine is active when taken orally and has a variable pharmacokinetic profile, with effects lasting several hours and requiring multiple daily doses in traditional regimens. It is non-selective with respect to autonomic ganglia and is known for a broad range of adverse effects that limit its tolerability. Consequently, its role in clinical practice has diminished, and it is now mainly encountered in historical reviews or research settings.

In addition to its antihypertensive history, mecamylamine has been studied as a pharmacological tool to investigate nicotinic receptors and, in some research contexts, as an adjunct in nicotine dependence trials. It is not a first-line therapy for smoking cessation today, owing to tolerability concerns and the availability of other treatments.

Contraindications and cautions include conditions where loss of autonomic regulation could be harmful and concurrent use with other agents that lower blood pressure or depress the central nervous system.