Mercilon Drug Interactions

Note: The prescribing information of concomitant medications should be consulted to identify potential interactions.
Effect of other medicinal products on Mercilon: Interactions can occur with medicinal or herbal products that induce microsomal enzymes, specifically cytochrome P450 enzymes (CYP), which can result in increased clearance of sex hormones and which may lead to breakthrough bleeding and/or contraceptive failure.
Management: 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.
Short-term treatment: Women on treatment with enzyme-inducing medicinal or herbal products should temporarily use a barrier method or another method of contraception in addition to the Mercilon. The barrier method must be used during the whole time of the concomitant drug therapy and for 28 days after its discontinuation.
Long-term treatment: In women on long-term therapy with enzyme-inducing active substances, another reliable, non-hormonal method of contraception unaffected by enzyme inducing medicinal products is recommended.
The following interactions have been reported in literature: Substances increasing the clearance of Mercilon (enzyme induction): Phenytoin, phenobarbital, primidone, bosentan, carbamazepine, rifampicin, some HIV protease inhibitors (e.g., ritonavir) and non-nucleoside reverse transcriptase inhibitors (e.g., efavirenz, nevirapine), and possibly also oxcarbazepine, topiramate, rifabutin, felbamate, griseofulvin, and products containing the herbal remedy St. John's wort.
Substances with variable effects on the clearance of Mercilon: When co-administered with hormonal contraceptives, many combinations of HIV protease inhibitors (e.g., nelfinavir) and non-nucleoside reverse transcriptase inhibitors (e.g., nevirapine), and/or combinations with Hepatitis C virus (HCV) medicinal products (e.g., boceprevir, telaprevir), can increase or decrease plasma concentrations of progestagens, including etonogestrel or estrogens. The net effect of these changes may be clinically relevant in some cases.
Therefore, the prescribing information of concomitant HIV/HCV medications should be consulted to identify potential interactions and any related recommendations. In case of any doubt, an additional barrier contraceptive method should be used by women on protease inhibitor or non-nucleoside reverse transcriptase inhibitor therapy.
Substances decreasing the clearance of Mercilon (enzyme inhibitors): The clinical relevance of potential interactions with enzyme inhibitors remains unknown.
Concomitant administration of strong (e.g., ketoconazole, itraconazole, clarithromycin) or moderate (e.g., fluconazole, diltiazem, erythromycin) CYP3A4 inhibitors may increase the serum concentrations of estrogens or progestagens, including etonogestrel.
Etoricoxib doses of 60 to 120 mg/day have been shown to increase plasma concentrations of ethinylestradiol 1.4 to 1.6-fold, respectively when taken concomitantly with a combined hormonal contraceptive containing 0.035 mg ethinylestradiol.
Effects of Mercilon on other medicinal products: Hormonal contraceptives COCs may interfere with the metabolism of other drugs. Accordingly, plasma and tissue concentrations may either increase (e.g., ciclosporin) or decrease (e.g. lamotrigine).
Clinical data suggests that ethinylestradiol is inhibiting the clearance of CYP1A2 substrates leading to a weak (e.g. theophylline) or moderate (e.g. tizanidine) increase in their plasma concentration.
Laboratory Tests: The use of contraceptive steroids may influence the results of certain laboratory tests, including biochemical parameters of liver, thyroid, adrenal and renal function, plasma levels of (carrier) proteins such as corticosteroid-binding globulin, lipid/lipoprotein fractions and parameters of carbohydrate metabolism, coagulation and fibrinolysis. Changes generally remain within the normal laboratory range.
Pharmacodynamic interactions: Concomitant use with medicinal products containing ombitasvir/paritaprevir/ritonavir and dasabuvir, with or without ribavirin may increase the risk of ALT elevations (see Contraindications and Warnings). Therefore, Mercilon users must switch to an alternative method of contraception (e.g., progestagen-only contraception or non-hormonal methods) prior to starting therapy with this combination drug regimen. Mercilon can be restarted 2 weeks following completion of treatment with this combination drug regimen.