Hexamethonium is a non-depolarising ganglionic blocker, a neuronal nicotinic (nAChR) receptor antagonist[1] that acts in autonomic ganglia by binding mostly in or on the nAChR receptor, and not the acetylcholine binding site itself. It does not have any effect on the muscarinic acetylcholine receptors (mAChR) located on target organs of the parasympathetic nervous system, nor on the nicotinic receptors at the skeletal neuromuscular junction, but acts as antagonist at the nicotinic acetylcholine receptors located in sympathetic and parasympathetic ganglia (nAChR).[2]
Pharmacology
By blocking the neuronal nicotinic receptors in autonomic ganglia, which are necessary for transmission in all autonomic ganglia, both the sympathetic and parasympathetic nervous systems are inhibited. Its action on the neuronal nicotinic receptors is primarily through the block of the ion pore, rather than through competition with the binding site for acetylcholine.[3]
Postganglionic sympathetic systems are usually regulated by norepinephrine (noradrenaline) (adrenergic receptors), whereas parasympathetic systems are acetylcholine-based, and instead rely on muscarinic receptors (some post-ganglionic sympathetic neurons, such as those stimulating sweat glands, release acetylcholine).[citation needed]
The use of inhaled hexamethonium, an unapproved drug, in a normal volunteer during a medical study is believed to have caused or contributed to her death[5][6] in light of the presence of abnormal "ground glass opacities" on her chest X-ray.[needs context]
↑Hardman JB, Limbird LE, Gilman AG (2001). Goodman and Gilman's The Pharmacological Basis of Therapeutics (10thed.). McGraw-Hill. pp.210–211. ISBN978-0071354691.
