Implanon NXT Drug Interactions

Note: The prescribing information of concomitant medications should be consulted to identify potential interactions.
Effects of other medicinal products on Implanon NXT: Interactions can occur with drugs that induce microsomal enzymes which can result in increased clearance of sex hormones and which may lead to menstrual bleeding and/or contraceptive failure.
Management: Enzyme induction can already be observed after a few days of treatment. Maximum enzyme induction is generally observed within a few weeks. After the cessation of drug therapy, enzyme induction may be sustained for about 4 weeks.
Women receiving hepatic enzyme-inducing drugs or herbal products should be advised that the efficacy of Implanon NXT may be reduced. Removal of the implant is not needed, but women are advised to use an additional non-hormonal contraceptive method during the time of concomitant drug administration and for 28 days after their discontinuation in order to obtain maximum protection.
The following interactions have been reported in the literature (mainly with combined contraceptives but occasionally also with progestagen-only contraceptives including Implanon NXT).
Substances increasing the clearance of hormonal contraceptives (diminished efficacy of hormonal contraceptives by enzyme-induction): E.g. Barbiturates, bosentan, carbamazepine, phenytoin, primidone, rifampicin, and HIV/HCV medication like ritonavir, efavirenz, boceprevir, nevirapine and possibly also felbamate, griseofulvin, oxcarbazepine, topiramate and products containing the herbal remedy St. John's Wort (Hypericum perforatum).
Substances with variable effects on the clearance of hormonal contraceptives: When co-administered with hormonal contraceptives, many combinations of HIV protease inhibitors and non-nucleoside reverse transcriptase inhibitors, including combinations with HCV inhibitors, can increase or decrease plasma concentrations of progestins, including etonogestrel. The net effect of these changes may be clinically relevant in some cases.
Therefore, the prescribing information on 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 hormonal contraceptives (enzyme inhibitors): Concomitant administration of strong (e.g. ketoconazole, itraconazole, clarithromycin) or moderate (e.g. fluconazole, diltiazem, erythromycin) CYP3A4 inhibitors may increase the serum concentrations of progestins, including etonogestrel.
Effects of Implanon NXT on other medicinal products: Hormonal contraceptives may affect metabolism of certain other active substances. Accordingly, plasma and tissue concentrations may either increase (e.g., ciclosporin) or decrease (e.g., lamotrigine).
Laboratory parameters: Data obtained with combined OCs have shown that contraceptive steroids may affect some laboratory parameters, including biochemical parameters of liver, thyroid, adrenal and renal function, serum levels of (carrier) proteins, e.g., corticosteroid binding globulin and lipid/lipoprotein fractions, parameters of carbohydrate metabolism and parameters of coagulation and fibrinolysis. The changes generally remain within the normal range. To what extent this also applies to progestagen-only contraceptives is not known.