Nexplanon (Etonogestrel)

Etonogestrel, a synthetic progestin, is indicated for hormonal contraception in women.

• Prevention of pregnancy: provides continuous release of progestin to inhibit ovulation and create cervical mucus changes that prevent fertilization for up to three years.
• Family planning: allows women to plan and space pregnancies without daily adherence, supporting reproductive autonomy and reducing unintended pregnancies.
• Long‑acting reversible contraception: offers a single‑procedure implant lasting up to three years, reducing the need for frequent dosing and improving compliance.

• Etonogestrel binds to progesterone receptors in the hypothalamus and pituitary, suppressing the luteinizing hormone surge required for ovulation. The hormone also thickens cervical mucus, creating a barrier to sperm penetration, and induces endometrial alterations that diminish the likelihood of implantation. Continuous low‑dose release from the subcutaneous rod maintains these effects throughout the implant’s lifespan and ensures consistent plasma concentrations throughout the intended duration of use.

Etonogestrel may be associated with a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Irregular bleeding or spotting
• Headache
• Acne
• Breast tenderness

Serious or Rare Side Effects

• Deep vein thrombosis or pulmonary embolism
• Infection at the insertion site
• Ectopic pregnancy if contraceptive failure occurs

Prior to implantation, clinicians should evaluate patients for contraindications and counsel on safe use.

• Confirm non‑pregnancy: verify the patient is not pregnant before insertion.
• Review thromboembolic history: avoid use in women with a history of blood clots or clotting disorders.
• Assess liver function: contraindicated in severe hepatic impairment.
• Evaluate medication interactions: consider drugs that may reduce contraceptive efficacy.
• Counsel on menstrual changes: inform patients that irregular bleeding is common.
• Store at ambient temperature: keep the implant in its original packaging, protect from moisture and direct sunlight.

Etonogestrel’s contraceptive effectiveness can be altered by concomitant medicines that affect hormone metabolism or protein binding.

Major Interactions (Avoid)

• Enzyme‑inducing anticonvulsants (e.g., carbamazepine, phenytoin, phenobarbital): may markedly reduce hormone levels.
• Rifampin or other strong CYP3A4 inducers: can decrease contraceptive efficacy.
• Protease inhibitors used in HIV therapy: may increase hormone concentrations and risk of side effects.

Moderate Interactions (Monitor Closely)

• Antibiotics such as tetracycline or metronidazole: may slightly lower effectiveness.
• St. John’s wort herbal supplement: may modestly reduce plasma etonogestrel levels.
• Antifungal agents (e.g., ketoconazole): can increase hormone levels, requiring monitoring.