Estradiol + Dydrogesterone Ritonavir
ModerateRitonavir can work the other way when it is taken with hormone medicines like estradiol and dydrogesterone. Ritonavir is known to block the CYP450 enzymes 3A4, A5 and A7, but when it is used together with steroid hormones it can instead speed these enzymes up. Nelfinavir behaves in the same way.
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.