Etonogestrel and ethinyl estradiol

Consult the labeling of all concurrently-used drugs to obtain further information about interactions with hormonal contraceptives or the potential for enzyme alterations. Drugs or herbal products that induce certain enzymes, such as CYP3A4, may decrease the effectiveness of CHCs or increase breakthrough bleeding. Counsel patients to use a back-up or alternative method of contraception when enzyme inducers are used with CHCs. ( 7 )

7.1 Effects of Other Drugs on CHCs Substances decreasing the plasma concentrations of CHCs and potentially diminishing the effectiveness of CHCs Drugs or herbal products that induce certain enzymes, including cytochrome P450 3A4 (CYP3A4), may decrease the plasma concentrations of CHCs and potentially diminish the effectiveness of CHCs or increase breakthrough bleeding. Some drugs or herbal products that may decrease the effectiveness of hormonal contraceptives include: phenytoin, barbiturates, carbamazepine, bosentan, felbamate, griseofulvin, oxcarbazepine, rifampicin, topiramate, rifabutin, rufinamide, aprepitant, and products containing St. John's wort.

Interactions between CHCs and other drugs may lead to breakthrough bleeding and/or contraceptive failure. Counsel women to use an alternative non-hormonal method of contraception or a back-up method when enzyme inducers are used with NuvaRing, and to continue back-up non-hormonal contraception for 28 days after discontinuing the enzyme inducer to ensure contraceptive reliability. Note: NuvaRing may interfere with the correct placement and position of certain female barrier methods such as a diaphragm or female condom. These methods are not recommended as back-up methods with NuvaRing use [see Dosage and Administration (2.5) ] .

The serum concentrations of etonogestrel and ethinyl estradiol were not affected by concomitant administration of oral amoxicillin or doxycycline in standard dosages during 10 days of antibiotic treatment. The effects of other antibiotics on etonogestrel or ethinyl estradiol concentrations have not been evaluated. Substances increasing the plasma concentrations of CHCs Co-administration of atorvastatin and certain CHCs containing ethinyl estradiol increase AUC values for ethinyl estradiol by approximately 20-25%. Ascorbic acid and acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation.

Concomitant administration of strong or moderate CYP3A4 inhibitors such as itraconazole, voriconazole, fluconazole, grapefruit juice, or ketoconazole may increase plasma estrogen and/or progestin concentrations. Co-administration of vaginal miconazole nitrate and NuvaRing increases the serum concentrations of etonogestrel and ethinyl estradiol by up to 40% [see Clinical Pharmacology (12.3) ] .

Human immunodeficiency virus (HIV) / Hepatitis C Virus (HCV) protease inhibitors and non-nucleoside reverse transcriptase inhibitors Significant changes in the plasma concentrations of the estrogen and /or progestin have been noted in some cases of co-administration with HIV protease inhibitors (decrease [e.g., nelfinavir, ritonavir, darunavir/ritonavir, (fos)amprenavir/ritonavir, lopinavir/ritonavir, and tipranavir/ritonavir] or increase [e.g., indinavir and atazanavir/ritonavir]) /HCV protease inhibitors (decrease [e.g., boceprevir and telaprevir]) or with non-nucleoside reverse transcriptase inhibitors (decrease [e.g., efavirenz, nevirapine] or increase [e.g., etravirine]).

These changes may be clinically relevant in some cases.

7.2 Effects of CHCs on Other Drugs CHCs containing ethinyl estradiol may inhibit the metabolism of other compounds (e.g., cyclosporine, prednisolone, theophylline, tizanidine, and voriconazole) and increase their plasma concentrations. CHCs have been shown to decrease plasma concentrations of acetaminophen, clofibric acid, morphine, salicylic acid and temazepam. A significant decrease in the plasma concentrations of lamotrigine has been shown, likely due to induction of lamotrigine glucuronidation. This may reduce seizure control; therefore, dosage adjustments of lamotrigine may be necessary.

Women on thyroid hormone replacement therapy may need increased doses of thyroid hormone because serum concentrations of thyroid-binding globulin increase with use of CHCs.

7.3 Concomitant Use with HCV Combination Therapy – Liver Enzyme Elevation Do not co-administer NuvaRing with HCV drug combinations containing ombitasvir/paritaprevir/ritonavir, with or without dasabuvir, due to potential for ALT elevations. Concomitant use with some other HCV antiviral medicinal products, such as those containing glecaprevir/pibrentasvir, may increase the risk of ALT elevations [see Warnings and Precautions (5.4) ] .

7.4 Interference with Laboratory Tests The use of contraceptive steroids may influence the results of certain laboratory tests, such as coagulation factors, lipids, glucose tolerance, and binding proteins.

8.1 Pregnancy Risk Summary NuvaRing is contraindicated during pregnancy because there is no need for pregnancy prevention in a woman who is already pregnant. Epidemiologic studies and meta-analyses have not shown an increased risk of genital or non-genital birth defects (including cardiac anomalies and limb-reduction defects) following maternal exposure to low dose CHCs prior to conception or during early pregnancy. No adverse developmental outcomes were observed in pregnant rats and rabbits with the administration of etonogestrel during organogenesis at doses approximately 300 times the anticipated daily vaginal human dose (~0.002 mg/kg/day).

No adverse developmental outcomes were observed in pregnant rats and rabbits with the co-administration of the combination desogestrel/ethinyl estradiol during organogenesis at desogestrel/ethinyl estradiol doses at least 2/5 times, respectively, the anticipated daily vaginal human dose (~0.002 desogestrel/0.00025 ethinyl estradiol mg/kg/day). Discontinue NuvaRing use if pregnancy is confirmed. Data Animal Data In rats and rabbits at dosages up to 300 times the anticipated dose, etonogestrel is neither embryotoxic nor teratogenic.

Co-administration of a maternally toxic dose of desogestrel/ethinyl estradiol to pregnant rats was associated with embryolethality and wavy ribs at a desogestrel/ethinyl estradiol dose that was 40/130 times, respectively, the anticipated vaginal human dose (0.002 desogestrel/0.00025 ethinyl estradiol mg/kg/day). No adverse embryofetal effects were observed when the combination was administered to pregnant rats at a desogestrel/ethinyl estradiol dose that was 4/13 times, respectively, the anticipated vaginal human dose.

When desogestrel/ethinyl estradiol was given to pregnant rabbits, pre-implantation loss was observed at a desogestrel/ethinyl estradiol dose that was 3/10 times, respectively, the anticipated vaginal human dose. No adverse embryofetal effects were observed when the combination was administered to pregnant rabbits at a desogestrel/ethinyl estradiol dose that was 2/5 times the anticipated vaginal human dose. Pregnancy Inform patients that NuvaRing is not to be used during pregnancy. If pregnancy is planned or occurs during treatment with NuvaRing, instruct the patient to discontinue NuvaRing use [see Use in Specific Populations (8.1) ] .