What are the characteristics and side effects of Nexplanon (etonogestrel) implants for contraception?

Nexplanon (Etonogestrel) Implant for Contraception

Nexplanon is the most effective reversible contraceptive method available, with a failure rate of only 0.05%, and should be considered first-line for women seeking highly effective, long-acting contraception that requires no user adherence. 1

Device Characteristics

Composition and Mechanism

• Nexplanon is a single-rod subdermal implant containing 68 mg of etonogestrel, the active metabolite of the progestin desogestrel 1
• The device is radiopaque (unlike its predecessor Implanon), allowing visualization on X-ray if localization is needed 2
• It is inserted subdermally in the inner aspect of the upper arm by a trained clinician 1

Duration and Efficacy

• FDA-approved for 3 years of continuous use 1, 3
• Both typical-use and perfect-use failure rates are less than 1%, with the Pearl Index of 0.05% making it more effective than sterilization 1
• Evidence suggests effectiveness may extend to 4 years, though this is not currently FDA-approved for routine practice 3
• No pregnancies occurred while implants were in place in clinical trials of 942 women 4

Continuation Rates

• 84% of users continue the method at 1 year, reflecting high satisfaction despite bleeding irregularities 1, 3
• In one study, the continuation rate was 93.8% at 12 months 5

Common Side Effects

Menstrual Changes (Most Common)

Unpredictable bleeding or spotting is the primary reason for discontinuation and must be thoroughly counseled before insertion. 1

• Menstrual pattern changes occur in the majority of users, but no single pattern predominates 4
• In clinical trials, 56.3% reported reduced bleeding, 3.1% increased bleeding, and 40.6% experienced combinations of bleeding patterns 5
• No participants maintained completely normal menstrual cycles in some studies 5

Other Frequent Adverse Effects (≥2% incidence)

• Headache (including migraine): 11.2% 6
• Mood changes (depression, mood swings, affect lability): 6.4% 6
• Weight gain: 4.9% 6
• Breast pain/discomfort/tenderness: 3.8% 6
• Acne: 2.4% 6
• Decreased libido: 2.0% 6, 5
• Nausea/vomiting: 5.9% 6

Device-Related Complications

• Device-related events (discomfort, foreign body sensation): 6.3% 6
• Insertion difficulties: 430 reports in a 10-year French surveillance study 7
• Removal difficulties, failure to locate, or migration: 1,137 reports over 10 years 7
• Important: Nexplanon has significantly reduced insertion/removal complications compared to Implanon (0.92 vs 1.31 per 1,000 patients) due to improved applicator design and radiopacity 7, 2
• Fibrosis around the implant was the most common removal complication at 4.4%, with mean removal time of 2 minutes 2

Serious Adverse Effects (Rare)

Cardiovascular

• Deep vein thrombosis has been reported 6
• The American Academy of Pediatrics notes that implants are considered safe for women with estrogen contraindications, as they contain only progestin 1

Pregnancy-Related

• 789 unintended pregnancies were reported over 10 years in France 7
• When circumstances were known, failures were due to: apparent implant inefficiency (n=224), technique failure (n=203), or drug-drug interactions (n=59) 7
• Six pregnancies occurred within 14 days after implant removal in clinical trials 4

Other Serious Events

• Anxiety, cholelithiasis, and vomiting have been reported 6
• Infectious complications at the implant site (infrequent) 7

Important Clinical Considerations

Contraceptive Counseling

• Backup contraception (condoms or abstinence) must be used for at least the first 7 days after insertion 1, 3
• Condoms should be used at all times for STI protection regardless of implant use 1

Drug Interactions

Hepatic enzyme-inducing drugs significantly reduce contraceptive efficacy and require alternative or additional contraceptive methods. 1, 3

• Medications that reduce effectiveness include: efavirenz, nevirapine, most protease inhibitors, phenytoin, barbiturates, carbamazepine, rifampicin, St. John's wort, and others 3, 6
• For patients on efavirenz, nevirapine, or most protease inhibitors, alternative or additional contraceptive methods should be used for the duration of treatment and the implant 3
• Standard oral antibiotics do NOT interfere with Nexplanon effectiveness 3

Special Populations

• Safe for immediate postpartum insertion, including while breastfeeding 1
• Studies show no adverse effects on breastfeeding performance or infant health and growth 1
• Safe for nulliparous adolescents 1
• Appropriate for women who cannot use estrogen-containing contraceptives 1

Discontinuation Rates

• 13.0% of women discontinued in clinical trials due to adverse reactions 6
• Most common reasons for discontinuation: device-related events (2.7%), mood changes (1.7%), headache (1.5%), and vaginal symptoms (1.2%) 6

Metabolic and Laboratory Effects

Weight and Blood Pressure

• Mean weight changes were not statistically significant at 6 months (71.4 kg to 70.0 kg, p<0.13) or 12 months (71.5 kg, p<0.88) 5
• Blood pressure showed statistically significant but clinically normal reductions at 12 months 5

Hematologic Effects

• No significant changes in packed cell volume or white blood cell count at 6 and 12 months 5
• Statistically significant increase in mean platelet count at 12 months (176,344 to 205,313 per µL, p<0.04) 5
• One case of thrombocytopenia without adverse effects was reported 5

Common Pitfalls to Avoid

1. Inadequate counseling about bleeding irregularities before insertion leads to premature removal 1
2. Failure to screen for drug interactions, particularly with antiretrovirals, resulting in contraceptive failure 3, 7
3. Not ensuring proper insertion technique by trained clinicians increases risk of migration and removal difficulties 7, 2
4. Forgetting to advise backup contraception for the first week after insertion 1, 3
5. Not counseling about STI protection—implants provide no protection against sexually transmitted infections 1