|AHFS/Drugs.com||International Drug Names|
|Elimination half-life||30–120 min|
|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||339.439 g·mol−1|
|3D model (JSmol)|
|Melting point||172 °C (342 °F)|
|Solubility in water||insoluble mg/mL (20 °C)|
|(what is this?)|
Methylergometrine (also called methylergonovine, methylergobasin, and d-lysergic acid 1-butanolamide) is a synthetic analogue of ergometrine, a psychedelic alkaloid found in ergot, and many species of morning glory. It is a member of the ergoline family and chemically similar to LSD, ergine, ergometrine, and lysergic acid. Due to its oxytocic properties, it has a medical use in obstetrics. According to Jonathan Ott, methylergonovine has LSD-like actions above 2 milligrams, due to its agonistic action at the 5HT2A-mGlu2 receptor protomers. Clinical efficacy occurs around 200 µg, ten times lower than the hallucinogenic threshold.
Methylergometrine maleate is marketed under the trade name Methergine.
Methylergometrine is a smooth muscle constrictor that mostly acts on the uterus. It is most commonly used to prevent or control excessive bleeding following childbirth and spontaneous or elective abortion, and also to aid in expulsion of retained products of conception after a missed abortion (miscarriage in which all or part of the fetus remains in the uterus) and to help deliver the placenta after childbirth. It is available as tablets or injection (IM or IV) or in liquid form to be taken orally.
Methylergometrine is contraindicated in patients with hypertension and pre-eclampsia. It is also contraindicated in HIV positive patients taking protease inhibitors, delavirdine and efavirenz (which is also an agonist at the 5HT2A-mGlu2 receptor protomer and increases the chances of a patient experiencing hallucinations during methylergometrine therapy).
Adverse effects include:
- Cholinergic effects such as nausea, vomiting, and diarrhea
- Pulmonary hypertension
- Coronary artery vasoconstriction
- Severe systemic hypertension (especially in patients with pre-eclampsia)
Methylergometrine likely interacts with drugs that inhibit the liver enzyme CYP3A4, such as azole antifungals, macrolide antibiotics and many HIV drugs. It can also increase constriction of blood vessels caused by sympathomimetic drugs and other ergot alkaloids.
Mechanism of action
Methylergometrine is a partial agonist/antagonist on serotonergic, dopaminergic and alpha-adrenergic receptors. Its specific binding and activation pattern on these receptors leads to a highly, if not completely, specific contraction of smooth uterus muscle via 5-HT2A serotonin receptors, while blood vessels are affected to a lesser extent compared to other ergot alkaloids.
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