From the FDA Drug Label
The plasma level decline was biphasic with a mean elimination half-life of 3. 39 hours (range 1.5 to 12.7 hours). The duration of action of Methergine (methylergonovine) is related to its elimination half-life, which is approximately 3.39 hours on average, but can range from 1.5 to 12.7 hours 1.
- The onset of action is immediate after intravenous administration, 2 to 5 minutes after intramuscular administration, and 5 to 10 minutes after oral administration.
- The duration of action is not explicitly stated, but based on the elimination half-life, it can be inferred that the effects of Methergine may last for several hours.
From the Research
Methergine (methylergonovine maleate) has a duration of action of approximately 3 to 6 hours when administered orally, and about 45 minutes to 3 hours when given intramuscularly or intravenously. This uterotonic medication is primarily used to prevent and treat postpartum hemorrhage by causing sustained uterine contractions. The relatively short duration necessitates repeated dosing when used for ongoing management of uterine atony. Typical oral dosing is 0.2 mg every 6-8 hours for up to 7 days postpartum, while parenteral administration is usually 0.2 mg intramuscularly every 2-4 hours for a maximum of 5 doses. Methergine works by directly stimulating smooth muscle receptors in the uterus, leading to increased tone, rate, and amplitude of rhythmic contractions. This action helps compress blood vessels and reduce bleeding. Patients should be monitored for hypertension during treatment as Methergine can cause significant vasoconstriction, and it is contraindicated in patients with hypertension and preeclampsia.
Some key points to consider when using Methergine include:
- The need for repeated dosing due to its relatively short duration of action
- The importance of monitoring for hypertension and other potential side effects
- The contraindication in patients with hypertension and preeclampsia
- The potential for additive or synergistic effects when used in combination with other uterotonics, such as oxytocin 2
- The comparison of Methergine with other uterotonics, such as carbetocin, misoprostol, and carboprost, in terms of efficacy and safety 3
It is essential to weigh the benefits and risks of Methergine and other uterotonics in the prevention and treatment of postpartum hemorrhage, considering the most recent and highest-quality evidence available 3.