Mergot Mechanism of Action

Pharmacology: Injection: Mechanism of Action: Methylergometrine maleate acts directly on the smooth muscle of the uterus and increases the tone, rate, and amplitude of rhythmic contractions. Thus, it induces a rapid and sustained tetanic uterotonic effect which shortens the third stage of labor and reduces blood loss.
Pharmacokinetics: Tablet: Methylergometrine Maleate is reportedly to be rapidly absorbed after administration by mouth and intramuscular injection. Elimination is rapid and appears to be by hepatic and renal routes. The absorption and fate of Methylergometrine Maleate had been studied following oral administration in healthy subjects and in postpartum women. Small amounts of Methylergometrine have been detected in breast milk.
Injection: Methylergometrine maleate is rapidly distributed from plasma to peripheral tissues within 2-3 minutes or less. During delivery, with intramuscular injection, bioavailability increased to 78%.
When given intramuscularly, the extent of absorption of Methylergometrine maleate solution was about 25% greater than the tablet. The volume of distribution Vdss/F of methylergometrine was calculated to be 56.1 ± 17.0 liters. The plasma level decline was biphasic with a mean elimination half-life of 3.39 hours (range 1.5 to 12.7 hours).