Metherspan Methylergonovine Maleate Ritonavir
ModerateRitonavir is one of the strong CYP3A4 inhibitors. That means it slows down the liver enzyme that clears methylergonovine from the body. Taking the two together can raise the level of methylergonovine in the blood, and that is exactly the situation the leaflet is warning about. Ritonavir belongs to the same group as the other HIV protease inhibitors named here (indinavir, nelfinavir, delavirdine), alongside macrolide antibiotics such as erythromycin and clarithromycin, and azole antifungals such as ketoconazole and itraconazole.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.