Zinnia P Drug Interactions

Note: The prescribing information of concomitant medications should be consulted to identify potential interactions.
Interactions: Enzyme inducers: Interactions can occur with drugs that induce microsomal enzymes (especially cytochrome P450 3A4) which can result in increased clearance of sex hormones and which may lead to breakthrough bleeding and/or contraceptive failure.
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.
Women on short term treatment with any of these drugs should temporarily use a barrier method in addition to the COC 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. If the period during which the barrier methods used runs beyond the last active tablet, the user should finish taking all the active tablets, discard the inert tablets and start a new pack of Levonorgestrel 150 mcg and Ethinylestradiol 30 mcg Tablets with Inert Tablets the next day with an appropriate active tablet. In this situation, a withdrawal bleed should not be expected until the end of the second pack. If the patient does not have a withdrawal bleed during the tablet free interval following the end of the second pack, the possibility of pregnancy must be ruled out before resuming with the next pack.
For women receiving long-term therapy with enzyme inducers, another method of contraception should be used. The following have been shown to have clinically important interactions with COCs: Anticonvulsants: barbiturates (including phenobarbitone), primidone, phenytoin, carbamazepine, oxcarbazepine, topiramate.
Antibiotics/antifungals: griseofulvin, rifampicin.
Herbal remedies: St John's wort (Hypericum perforatum).
Antiretroviral agents: ritonavir, nelfinavir, nevirapine.
Note: There are other antiretroviral agents that may increase plasma concentration of sex hormones.
Substances decreasing the clearance of COCs (enzyme inhibitors): Strong and moderate CYP3A4 inhibitors such as azole antifungals (e.g. itraconazole, voriconazole, fluconazole), and macrolides (e.g. erythromycin) can increase plasma concentrations of the oestrogen or the progestin or both.
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 on other drugs: Oral contraceptives may affect the metabolism of certain other drugs. Accordingly, plasma and tissue concentrations may either increase (e.g. cyclosporin, tizanidine, theophylline) or decrease (e.g. lamotrigine).
Pharmacodynamic interactions: Concomitant use with medicinal products containing ombitasvir/paritaprevir/ritonavir, dasabuvir, with or without ribavirin, glecaprevir/pibrentasvir and sofosbuvir/velpatasvir/voxilaprevir, may increase the risk of ALT elevations (see Contraindications and Precautions).
Therefore, Levonorgestrel 150 mcg and Ethinylestradiol 30 mcg Tablets with Inert Tablets-users must switch to an alternative method of contraception (e.g., progestogen-only contraception or non-hormonal methods) prior to starting therapy with these drug regimens. Levonorgestrel 150 mcg and Ethinylestradiol 30 mcg Tablets with Inert Tablets can be restarted 2 weeks following completion of treatment with these drug regimens.
Laboratory tests: The use of oral contraceptives 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. corticosteroid binding globulin and lipid/lipoprotein fractions, parameters of carbohydrate metabolism and parameters of coagulation and fibrinolysis. Laboratory staff should therefore be informed about oral contraceptive use when laboratory tests are requested.