Trimethaphan

Trimethaphan is a ganglionic blocker that was introduced in the mid-20th century for the treatment of hypertension. It is a short-acting, non-depolarizing ganglion blocker that acts by inhibiting the nicotinic acetylcholine receptors (nAChRs) at the autonomic ganglia, thereby preventing the transmission of impulses along the autonomic nervous system.

Pharmacology

Trimethaphan acts as a competitive antagonist at the nAChRs, blocking the action of acetylcholine and other agonists. It is a non-depolarizing agent, meaning that it does not cause a persistent depolarization of the ganglia, but rather prevents the depolarization from occurring in the first place. This results in a decrease in the activity of both the sympathetic nervous system and the parasympathetic nervous system, leading to effects such as a decrease in blood pressure.

Clinical uses

Trimethaphan was primarily used in the acute management of hypertensive emergencies. It was also used in the management of aortic dissection and pulmonary edema. However, due to the availability of newer, safer, and more effective drugs, it is no longer commonly used.

Side effects

The most common side effects of trimethaphan are related to its action as a ganglionic blocker. These include hypotension, bradycardia, dry mouth, and blurred vision. In rare cases, it can cause respiratory failure due to paralysis of the respiratory muscles.

History

Trimethaphan was first synthesized in the 1940s and was introduced into clinical practice in the 1950s. It was one of the first drugs to be used in the treatment of hypertension. However, its use has declined significantly since the introduction of newer antihypertensive drugs.