METHYLERGONOVINE Drug Interactions: What You Need to Know

Drug Interactions CYP 3A4 Inhibitors (e.g., Macrolide Antibiotics and Protease Inhibitors) There have been rare reports of serious adverse events in connection with the coadministration of certain ergot alkaloid drugs (e.g., dihydroergotamine and ergotamine) and potent CYP 3A4 inhibitors, resulting in vasospasm leading to cerebral ischemia and/or ischemia of the extremities. Although there have been no reports of such interactions with methylergonovine alone, strong and moderate CYP 3A4 inhibitors should not be co-administered with methylergonovine. Examples of some of the strong CYP 3A4 inhibitors include saquinavir, grapefruit juice, nefazodone, macrolide antibiotics (e.g., troleandomycin, clarithromycin), HIV protease or reverse transcriptase inhibitors (e.g., ritonavir, indinavir, nelfinavir) or azole antifungals (e.g., ketoconazole, itraconazole, voriconazole). Moderate inhibitors include fluconazole, fluvoxamine and clotrimazole. Weak CYP 3A4 inhibitors should be administered with caution. Weak inhibitors include chlorzoxazone, cilostazol, and ranitidine. These lists are not exhaustive, and the prescriber should consider the effects on CYP 3A4 of other agents being considered for concomitant use with methylergonovine. CYP3A4 inducers Drugs (e.g. nevirapine, rifampin) that are strong inducers of CYP3A4 are likely to decrease the pharmacological action of Methylergonovine Maleate Injection. Beta-blockers Caution should be exercised when Methylergonovine Maleate Injection is used concurrently with beta-blockers. Concomitant administration with beta-blockers may enhance the vasoconstrictive action of ergot alkaloids.

Anesthetics

Anesthetics like halothane and methoxyflurane may reduce the oxytocic potency of Methylergonovine Maleate Injection. Glyceryl trinitrate and other antianginal drugs Methylergonovine maleate produces vasoconstriction and can be expected to reduce the effect of glyceryl trinitrate and other antianginal drugs. No pharmacokinetic interactions involving other cytochrome P450 isoenzymes are known. Caution should be exercised when Methylergonovine Maleate Injection is used concurrently with other vasoconstrictors, ergot alkaloids, or prostaglandins.

CONTRAINDICATIONS Hypertension; toxemia; pregnancy; and hypersensitivity.

WARNINGS General This drug should not be administered I.V. routinely because of the possibility of inducing sudden hypertensive and cerebrovascular accidents. If I.V administration is considered essential as a lifesaving measure, methylergonovine maleate should be given slowly over a period of no less than 60 seconds with careful monitoring of blood pressure. Intra-arterial or periarterial injection should be strictly avoided. Caution should be exercised in presence of impaired hepatic or renal function. Breast-feeding Mothers should not breast-feed during treatment with methylergonovine maleate tablets, USP. Milk secreted during this period should be discarded. Methylergonovine maleate tablets, USP may produce adverse effects in the breast-feeding infant. Methylergonovine maleate tablets, USP may also reduce the yield of breast milk. Mothers should wait at least 12 hours after administration of the last dose of methylergonovine maleate tablets, USP before initiating or resuming breast feeding. Coronary artery disease Patients with coronary artery disease or risk factors for coronary artery disease (e.g., smoking, obesity, diabetes, high cholesterol) may be more susceptible to developing myocardial ischemia and infarction associated with methylergonovine-induced vasospasm. Medication errors Inadvertent administration of methylergonovine maleate tablets, USP to newborn infants has been reported. In these cases of inadvertent neonatal exposure, symptoms such as respiratory depression, convulsions, cyanosis and oliguria have been reported. Usual treatment is symptomatic. However, in severe cases, respiratory and cardiovascular support is required. Methylergonovine maleate tablets, USP have been administered instead of vitamin K and Hepatitis B vaccine, medications which are routinely administered to the newborn. Due to the potential for accidental neonatal exposure, methylergonovine maleate should be stored separately from medications intended for neonatal administration.