Levoplant Drug Interactions

Effects of other medicinal products on Levonorgestrel (Levoplant): Interactions can occur with drugs that induce microsomal enzymes, which can result in increased clearance of sex hormones and which may lead to changes in the uterine bleeding profile and/or contraceptive failure.
Women on treatment with any of these drugs should temporarily use a barrier method in addition to Levonorgestrel (Levoplant) or choose another method of contraception. The barrier method should be used during the time of concomitant drug administration and for 28 days after their discontinuation.
Substances increasing the clearance of levonorgestrel (diminished efficacy of Levonorgestrel (Levoplant) by enzyme-induction), e.g.: Phenytoin, barbiturates, primidone, carbamazepine, rifampicin, efavirenz, and possibly also oxcarbazepine, topiramate, bosentan, felbamate, griseofulvin and products containing St. John's wort.
Enzyme induction can already be observed after a few days of treatment.
Maximal enzyme induction is generally seen within a few weeks. After the cessation of drug therapy enzyme induction may be sustained for about 4 weeks.
Levonorgestrel (Levoplant) users should be warned of the possibility of decreased contraceptive efficacy when using medicinal products exhibiting enzyme-inducing activity such as those mentioned previously. Breakthrough bleeding and unintended pregnancies have been reported.
Substances decreasing the clearance of Levonorgestrel (Levoplant) (enzyme inhibitors): Strong and moderate CYP3A4 inhibitors such as azole antifungals (e.g. itraconazole, voriconazole, fluconazole), verapamil, macrolides (e.g. clarithromycin, erythromycin) and diltiazem and grapefruit juice can increase plasma concentrations of the progestin.
Substances with variable effects on the clearance of levonorgestrel: When co-administered, many HIV medications can decrease or increase plasma concentrations of levonorgestrel (decrease [e.g. nevirapine, etravirine, efavirenz], or increase [ritonavir, darunavir/ritonavir, lopinavir/ritonavir, atazanavir/ritonavir, tipranavir/ritonavir, and (fos)amprenavir/ritonavir, indinavir]). These changes may be clinically relevant in some cases. (Note: Women with HIV were excluded from the pivotal clinical study.)
Effects of Levonorgestrel (Levoplant) on other medicinal products: Levonorgestrel (Levoplant) may affect the metabolism of other medicinal products. Accordingly, plasma and tissue concentrations may either increase (e.g. cyclosporin) or decrease (e.g. lamotrigine). Note: The prescribing information of concomitant medications should be consulted to identify potential interactions.
Other forms of interaction: Laboratory tests: The use of contraceptive steroids may influence the results of certain laboratory tests. Levonorgestrel (Levoplant) implants may have the following effects on the results of some endocrine laboratory tests: 1. Reduce the concentration of SHBG (sex hormone binding globulin).
2. Decrease thyroxine concentration in serum and elevate the values in triiodothyronine binding test.