METHYLERGOMETRINE 0.2MG/ML INJECTION

Indications

• Postpartum hemorrhage
• Post-abortion hemorrhage
• Control of uterine atony

Dosage

Children: Refer to the BNF for Children for specific dosing guidelines.

Adults: Refer to the BNF for specific dosing guidelines.

Mechanism of action

Methylergometrine acts directly on the smooth muscle of the uterus, increasing the tone, rate, and amplitude of rhythmic contractions through binding and antagonism of the dopamine D1 receptor. This results in a rapid and sustained tetanic uterotonic effect, which shortens the third stage of labor and reduces blood loss. It also stimulates contractions of the cervix and produces vasoconstriction, mainly of capacitance vessels, which may elevate blood pressure.

Pharmacodynamics

Methylergometrine, as a derivative of ergonovine, functions as a partial agonist or antagonist at adrenergic, dopaminergic, and tryptaminergic receptors. Its effects vary with dosage, species, and physiological conditions. At lower doses, it enhances uterine contractions with periods of relaxation, while higher doses result in sustained contractions with increased resting tone and potentially prolonged contracture. It significantly increases motor activity in the uterus, aiding in the management of hemorrhage.

Pharmacokinetics

Methylergometrine is typically administered intravenously or intramuscularly, with onset of action occurring rapidly. The drug is metabolized in the liver and excreted primarily in the urine. Due to its effects on smooth muscle and its vasoconstrictive properties, careful monitoring of blood pressure and uterine tone is advisable during its use.

Contra-indications

• Hypersensitivity to methylergometrine or any of its components
• Severe hypertension
• Preeclampsia or eclampsia
• Obstetric conditions where increased uterine activity is contraindicated

Adverse effects

• Nausea
• Vomiting
• Headache
• Hypertension
• Bradycardia
• Uterine hypertonicity
• Peripheral vasoconstriction
• Gangrene (rare)

Interactions

• Antihypertensives (may have additive effects)
• Sympathomimetics (may enhance vasoconstriction)
• Dopaminergic agents (may antagonize effect)

Precautions

• Monitor blood pressure closely during use
• Use cautiously in patients with cardiovascular disease
• Administer with care to avoid excessive uterine contractions

Pregnancy

Methylergometrine is used during the third stage of labor to manage postpartum hemorrhage. It should only be used when the benefits outweigh potential risks.

Breast-feeding

Methylergometrine is excreted in breast milk; caution is advised when administering to breastfeeding mothers.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Formulations

• Tablets
• Injection solution

Mechanism of action

Methylergometrine acts directly on the smooth muscle of the uterus and increases the tone, rate, and amplitude of rhythmic contractions through binding and the resultant antagonism of the dopamine D1 receptor. Thus, it induces a rapid and sustained tetanic uterotonic effect which shortens the third stage of labor and reduces blood loss. Methylergonovine 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. Ergonovine maleate and methylergonovine maleate are pharmacologically similar. Both drugs directly stimulate contractions of uterine and vascular smooth muscle. Following administration of usual therapeutic doses of ergonovine or methylergonovine, intense contractions of the uterus are produced and are usually followed by periods of relaxation. Larger doses of the drugs, however, produce sustained, forceful contractions followed by only short or no periods of relaxation. The drugs increase the amplitude and frequency of uterine contractions and uterine tone which in turn impede uterine blood flow. Ergonovine and methylergonovine also increase contractions of the cervix. Ergonovine and methylergonovine produce vasoconstriction, mainly of capacitance vessels; increased central venous pressure, elevated blood pressure, and, rarely, peripheral ischemia and gangrene may result. Methylergonovine reportedly may interfere with prolactin secretion, but this effect has not been definitely established. Ergot alkaloids are antagonists of actions of 5-hydroxytryptamine and of certain metabolic actions of catecholamines. /Ergot alkaloids/

Pharmacodynamics

Methylergometrine is a semisynthetic ergot alkaloid and a derivative of ergonovine and is used for the prevention and control of postpartum and post-abortion hemorrhage. In general, the effects of all the ergot alkaloids appear to results from their actions as partial agonists or antagonists at adrenergic, dopaminergic, and tryptaminergic receptors. The spectrum of effects depends on the agent, dosage, species, tissue, and experimental or physiological conditions. All of the alkaloids of ergot significantly increase the motor activity of the uterus. After small doses contractions are increased in force or frequency, or both, but are followed by a normal degree of relaxation. As the dose is increased, contractions become more forceful and prolonged, resting tonus is markedly increased, and sustained contracture can result.