Women should be informed that IMPLANON (etonogestrel implant) 68 mg does not protect against infection from HIV (the virus that causes AIDS) or other sexually transmitted diseases.
Important: Pregnancy must be excluded before inserting this product.
IMPLANON may induce mild insulin resistance and small changes in glucose concentrations of unknown clinical significance. Women with diabetes or impaired glucose tolerance should be carefully observed while using IMPLANON.
Women who are being treated for hyperlipidemias should be followed closely if they elect to use hormonal contraceptives. Some progestins may elevate LDL levels and may render the control of hyperlipidemias more difficult.
Changes in contraceptive effectiveness associated with coadministration of other drugs
Anti-infective agents and anticonvulsants
IMPLANON is not recommended for women who require chronic use of drugs that are potent inducers of hepatic enzymes because IMPLANON is likely to be less effective for these women.
Contraceptive effectiveness may be reduced when hormonal contraceptives are co-administered with some antibiotics, antifungals, anticonvulsants, and other drugs that increase the metabolism of contraceptive steroids. This could result in an unintended pregnancy or breakthrough bleeding. Examples include: barbiturates, griseofulvin, rifampin, phenylbutazone, phenytoin, carbamazepine, felbamate, oxcarbazepine, topiramate, and modafinil. Patients should use an additional non-hormonal contraceptive method when taking medications that may decrease the efficacy of hormonal contraceptives.
Anti-HIV protease inhibitors
Several of the anti-HIV protease inhibitors have been studied with co-administration of combination oral contraceptives; significant changes (increase and decrease) in the mean area under the curve (AUC) of the estrogen and progestin have been noted in some cases. The efficacy and safety of combination oral contraceptive products may be affected with coadministration of anti-HIV protease inhibitors; it is unknown whether this applies to IMPLANON. Healthcare providers should refer to the labeling of the individual anti-HIV protease inhibitors for further drug-drug interaction information.
Herbal products containing St. John’s Wort (Hypericum perforatum) may induce hepatic enzymes and p-glycoprotein transporter and may reduce the effectiveness of contraceptive steroids.
Increase in plasma hormone levels associated with coadministered drugs
Inhibitors of hepatic enzymes such as itraconazole or ketoconazole may increase plasma hormone levels.
Certain endocrine tests may be affected by IMPLANON use:
a. Sex hormone-binding globulin concentrations may be decreased for the first six months after IMPLANON insertion followed by a gradual recovery.
b. Thyroxine concentrations may initially be slightly decreased followed by gradual recovery to baseline.
IMPLANON is not indicated for use during pregnancy.
Teratology studies have been performed in rats and rabbits, respectively, using oral administration up to 390 and 790 times the human IMPLANON dose (based upon body surface) and revealed no evidence of fetal harm due to ENG exposure.
Studies have revealed no increased risk of birth defects in women who have used combination oral contraceptives before pregnancy or during early pregnancy. There is no evidence that the risk associated with IMPLANON is different from that of combination oral contraceptives. IMPLANON should be removed if maintaining a pregnancy.
Based on limited data, IMPLANON may be used during lactation after the fourth postpartum week. Use of IMPLANON before the fourth postpartum week has not been studied.
Small amounts of ENG are excreted in breast milk. During the first months after IMPLANON insertion, when maternal blood levels of ENG are highest, about 100 ng of ENG may be ingested by the child per day based on an average daily milk ingestion of 658 mL. Based on daily milk ingestion of 150 mL/kg, the mean daily infant ENG dose one month after insertion of IMPLANON is about 2.2% of the weight-adjusted maternal daily dose, or about 0.2% of the estimated absolute maternal daily dose. The health of breast-fed infants whose mothers began using IMPLANON during the fourth to eighth week postpartum (n=38) was evaluated in a comparative study with infants of mothers using a non-hormonal IUD (n=33). They were breast-fed for a mean duration of 14 months and followed up to 36 months of age. No significant effects and no differences between the groups were observed on the physical and psychomotor development of these infants. No differences between groups in the production or quality of breast milk were detected.
Healthcare providers should discuss both hormonal and nonhormonal contraceptive options, as steroids may not be the initial choice for these patients.