Vinca Drug Interactions

Effects of other medication on Dienogest (Vinca): Progestins including Dienogest are metabolized mainly by the cytochrome P450 3A4 system (CYP3A4) located both in the intestinal mucosa and in the liver. Therefore, inducers or inhibitors of CYP3A4 may affect the progestogen drug metabolism.
An increased clearance of sex hormones due to enzyme induction may reduce the therapeutic effect of Dienogest (Vinca) and may result in undesirable effects e.g. changes in the uterine bleeding profile.
A reduced clearance of sex hormones due to enzyme inhibition may increase the exposure to Dienogest and may result in undesirable effects.
Substances increasing the clearance of sex hormones (diminished efficacy by enzyme-induction), e.g.: Phenytoin, barbiturates, primidone, carbamazepine, rifampicin, and possibly also oxcarbazepine, topiramate, felbamate, griseofulvin, and products containing St. John's wort.
Enzyme induction can already be observed after a few days of treatment. Maximum enzyme induction is generally seen within a few weeks. After the cessation of drug therapy enzyme induction may be sustained for about 4 weeks.
The effect of the CYP 3A4 inducer rifampicin was studied in healthy postmenopausal women. Co-administration of rifampicin with estradiol valerate/dienogest tablets led to significant decreases in steady state concentrations and systemic exposures of dienogest. The systemic exposure of dienogest at steady state, measured by AUC(0-24h), were decreased by 83%.
Substance with variable effects in the clearance of sex hormones, e.g.: When co-administered with sex hormones, many HIV/HCV protease inhibitors and non-nucleoside reverse transcriptase inhibitors can increase or decrease plasma concentrations of the progestin. These changes may be clinically relevant in some cases.
Substances decreasing the clearance of sex hormones (enzyme inhibitors): Dienogest is a substrate of cytochrome P450 (CYP) 3A4.
Strong and moderate CYP3A4 inhibitors such as azole antifungals (e.g. itraconazole, voriconazole, fluconazole), verapamil, macrolides (e.g. clarithromycin, erythromycin), diltiazem and grapefruit juice may increase plasma levels of the progestin.
In a study investigating the effect of CYP3A4 inhibitors (ketoconazole, erythromycin) on the combination of estradiol valerate/dienogest, steady state dienogest plasma levels were increased. Co-administration with the strong inhibitor ketoconazole resulted in a 186% increase of AUC(0-24h) at steady state for dienogest. When co-administered with the moderate inhibitor erythromycin, the AUC (0-24h) of dienogest at steady state were increased by 62%.
The clinical relevance of these interactions is unknown.
Effects of Dienogest (Vinca) on other medication: Based on in vitro inhibition studies, a clinically relevant interaction of Dienogest with the cytochrome P450 enzyme mediated metabolism of other medicaments is unlikely.
Note: The prescribing information of concomitant medication should be consulted to identify potential interactions.
Drug-food interaction: A standardized high fat meal did not affect the bioavailability of Dienogest (Vinca).
Other forms of interactions: The use of progestogens may influence the results of certain laboratory tests, including biochemical parameters of liver, thyroid, adrenal and renal function, plasma levels of (carrier) proteins e.g. lipid/lipoprotein fractions, parameters of carbohydrate metabolism and parameters of coagulation and fibrinolysis. Changes generally remain within the normal laboratory range.