Hexamethonium
Hexamethonium is a non-depolarising ganglionic blocker, a nicotinic receptor antagonist 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 located on target organs of the parasympathetic nervous system but acts as antagonist at the nicotinic acetylcholine receptors located in sympathetic and parasympathetic ganglia.Pharmacology
It can act on receptors at pre-ganglionic sites in both the sympathetic and parasympathetic nervous systems, which are both regulated by nicotinic ligand-gated ionotropic acetylcholine receptors. Postganglionic sympathetic systems are usually regulated by norepinephrine , whereas parasympathetic systems are acetylcholine-based, and instead rely on muscarinic receptors.
The organ system and adverse effects of ganglion blockers are due to the parasympathetic and sympathetic stimuli blockage at preganglionic sites. Side-effects include combined sympatholytic and parasympatholytic effects.Uses
It was formerly used to treat disorders, such as chronic hypertension, of the peripheral nervous system, which is innervated only by the sympathetic nervous system. The non-specificity of this treatment led to discontinuing its use.
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 in light of the presence of abnormal "ground glass opacities" on her chest X-ray.
