Safety and efficacy of a single-rod etonogestrel implant (Implanon): results from 11 international clinical trials

Objective

To present efficacy, safety, and bleeding profile results from the clinical trials that supported the U.S. Food and Drug Administration filing for the approval of a single-rod etonogestrel (ENG) contraceptive implant (Implanon).

Design

Integrated analysis of 11 international clinical trials.

Setting

Contraceptive clinics in U.S., Chile, Asia, and Europe.

Patient(s)

A total of 942 healthy women, aged 18 to 40 years.

Intervention(s)

Insertion of an ENG implant. Most women were enrolled in studies lasting either 2 or 3 years.

Main Outcomes Measure(s)

Efficacy was measured by the cumulative Pearl Index in women ≤35 years old. Safety was primarily assessed by incidence of adverse events. Bleeding profiles were analyzed via reference period analyses.

Result(s)

No pregnancies were reported while the ENG implants were in place. Six pregnancies occurred during the first 14 days after ENG implant removal. Including these six pregnancies, the cumulative Pearl Index was 0.38 (year 1 and 2 Pearl Indexes were 0.27 and 0.30, respectively). Common drug-related adverse events were headache, weight gain, acne, breast tenderness, emotional lability, and abdominal pain. Bleeding pattern changes were observed, but no one pattern predominated.

Conclusion(s)

The ENG implant is an efficacious and safe method of contraception which does not require patients' consistent action.

Key Words: Contraceptive implant, etonogestrel, menstruation, desogestrel, levonorgestrel