Hexamethonium is a non-depolarising ganglionic blocker, a nicotinic (

nAChR Nicotinic acetylcholine receptors, or nAChRs, are receptor polypeptides that respond to the neurotransmitter acetylcholine. Nicotinic receptors also respond to drugs such as the agonist nicotine. They are found in the central and peripheral ner ...

)

receptor antagonist A receptor antagonist is a type of receptor ligand or drug that blocks or dampens a biological response by binding to and blocking a receptor rather than activating it like an agonist. Antagonist drugs interfere in the natural operation of rece ...

that acts in

autonomic ganglia An autonomic ganglion is a cluster of nerve cell bodies (a ganglion) in the autonomic nervous system The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that s ...

by binding mostly in or on the

receptor, and not the

acetylcholine Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Part ...

binding site itself. It does not have any effect on the muscarinic acetylcholine receptors ( mAChR) located on target organs of the

parasympathetic nervous system The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of ...

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 (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). The organ system and adverse effects of

ganglion blockers A ganglionic blocker (or ganglioplegic) is a type of medication that inhibits transmission between preganglionic and postganglionic neurons in the autonomic nervous system, often by acting as a nicotinic receptor antagonist. Nicotinic acetylcholi ...

are due to the parasympathetic and sympathetic stimuli blockage at preganglionic sites. Side-effects include combined

sympatholytic A sympatholytic (or sympathoplegic) drug is a medication that opposes the downstream effects of postganglionic nerve firing in effector organs innervated by the sympathetic nervous system (SNS). They are indicated for various functions; for example, ...

(e.g., orthostatic hypotension and sexual dysfunction) and parasympatholytic (e.g., constipation, urinary retention, glaucoma, blurry vision, decreased lacrimal gland secretion, dry mouth ( xerostomia)) effects.

Uses

It was formerly used to treat disorders, such as chronic

hypertension Hypertension (HTN or HT), also known as high blood pressure (HBP), is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms. Long-term high bl ...

, of the peripheral nervous system, which is innervated only by the

sympathetic nervous system The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of th ...

. 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.

References

{{Nicotinic acetylcholine receptor modulators Nicotinic antagonists Quaternary ammonium compounds

Pharmacology

Uses

See also

References