 | |
 | |
| Clinical data | |
|---|---|
| Trade names | Arfonad |
| Routes of administration | Oral,IM,IV |
| ATC code | |
| Pharmacokinetic data | |
| Excretion | Renal, mostly unchanged |
| Identifiers | |
| |
| CAS Number |
|
| PubChemCID | |
| DrugBank |
|
| UNII | |
| KEGG | |
| ChEMBL | |
| CompTox Dashboard(EPA) | |
| ECHA InfoCard | 100.000.633 |
| Chemical and physical data | |
| Formula | C22H25N2OS (free base) |
| Molar mass | 365.52 g·mol−1 |
 N Y (what is this?) (verify) | |
Trimetaphan camsilate (INN) ortrimethaphan camsylate (USAN), sold under the trade nameArfonad, is asympatholytic drug that is infrequently used to lowerblood pressure.
Trimetaphan is aganglionic blocker: it counteractscholinergic transmission at thea specific type ofnicotinic acetylcholine receptors in theautonomic ganglia and, therefore, blocks both thesympathetic nervous system and theparasympathetic nervous system. It functions as a non-depolarizingcompetitive antagonist at the nicotinic receptor, has a short duration of action, and is administered intravenously.
It was discovered byLeo Sternbach.[1]
Trimetaphan is asulfonium compound and, as such, carries a positive charge. This charge prevents it from crossinglipidcell membranes, including those that comprise theblood–brain barrier. Consequently, trimethaphan has no effect on thecentral nervous system.
Theciliary muscle of theeye functions to round thelens foraccommodation and is primarily controlled by parasympathetic system input. When a ganglion-blocking drug is administered, the ciliary muscle is unable to contract (cycloplegia), and the patient loses the ability to focus.
Trimetaphan has a significant effect on thecardiovascular system. Blood vessel size is primarily controlled by the sympathetic nervous system. Loss of sympathetic system input to theblood vessels causes them to dilate (vasodilation), which lowersblood pressure.Postural hypotension is a common side effect of these drugs. Trimethaphan causes histamine release, further decreasing blood pressure. Effects on theheart include a decreased force of contraction and an increase in heart rate (tachycardia). Reflexive tachycardia can be diminished or undetected because trimetaphan also blocks the sympathetic ganglia innervating the heart.
The motility of thegastrointestinal tract is regulated by the parasympathetic system, and blockage of this input results in diminished motility andconstipation.
A rare side effect of trimethaphan administration is suddenrespiratory arrest. The mechanism behind this is unknown, as trimethaphan does not appear to block theneuromuscular transmission, and respiratory arrest is not an expected consequence of ganglionic blockage.[2]
The therapeutic uses of trimetaphan are limited due to the availability of newer drugs that are more selective in their actions and effects. It is occasionally used to treat ahypertensive crisis anddissecting aortic aneurysm, to treatpulmonary edema, and to reduce bleeding duringneurosurgery.
 | This article includes a list ofgeneral references, butit lacks sufficient correspondinginline citations. Please help toimprove this article byintroducing more precise citations.(September 2018) (Learn how and when to remove this message) |