Pharmacology Of Ergonovine

Indication	Used to treat postpartum haemorrhage and postabortion haemorrhage in patients with uterine atony.
Pharmacodynamics	Ergonovine belongs to the group of medicines known as ergot alkaloids. These medicines are usually given to stop excessive bleeding that sometimes occurs after abortion or a baby is delivered. They work by causing the muscle of the uterus to contract.
Mechanism of action	Ergonovine directly stimulates the uterine muscle to increase force and frequency of contractions. With usual doses, these contractions precede periods of relaxation; with larger doses, basal uterine tone is elevated and these relaxation periods will be decreased. Contraction of the uterine wall around bleeding vessels at the placental site produces hemostasis. Ergonovine also induces cervical contractions. The sensitivity of the uterus to the oxytocic effect is much greater toward the end of pregnancy. The oxytocic actions of ergonovine are greater than its vascular effects. Ergonovine, like other ergot alkaloids, produces arterial vasoconstriction by stimulation of alpha-adrenergic and serotonin receptors and inhibition of endothelial-derived relaxation factor release. It is a less potent vasoconstrictor than ergotamine. As a diagnostic aid (coronary vasospasm), ergonovine causes vasoconstriction of coronary arteries.
Absorption	Absorption is rapid and complete after oral or intramuscular administration.
Volume of distribution	Not Available
Protein binding	Not Available
Metabolism	Hepatic.
Route of elimination	Thought to be eliminated by non-renal mechanisms (i.e. hepatic metabolism, excretion in feces)
Half life	t1/2 α=10 minutes; t1/2 β=2 hours
Clearance	Not Available
Toxicity	The principal symptoms of overdose are convulsions and gangrene. Other symptoms include bradycardia, confusion, diarrhoea, dizziness, dyspnoea, drowsiness, fast and/or weak pulse, miosis, hypercoagulability, loss of consciousness, nausea and vomiting, numbness and coldness of the extremities, pain in the chest, peripheral vasoconstriction, respiratory depression, rise or fall in blood pressure, severe cramping of the uterus, tachycardia, tingling, and unusual thirst.