The pharmacokinetics of 12-week continuous contraceptive patch use

Area of Science:

• Reproductive Endocrinology
• Pharmacokinetics
• Contraception

Background:

• Continuous combined hormonal contraceptives offer potential benefits over traditional cyclic regimens.
• Understanding drug accumulation is crucial for assessing the safety and efficacy of extended-use contraceptive methods.

Purpose of the Study:

• To evaluate serum ethinyl estradiol (EE2) and norelgestromin (NGMN) levels during 12 weeks of continuous contraceptive patch use.
• To determine the pharmacokinetic profile of EE2 and NGMN with extended, uninterrupted patch application.

Main Methods:

• A prospective study involving 30 participants applying contraceptive patches continuously for 12 weeks.
• Serial blood sampling weekly and twice-weekly at key time points (weeks 4, 8, 12).
• Quantification of EE2 and NGMN using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Main Results:

• Serum EE2 levels demonstrated a statistically significant accumulation over 12 weeks at an estimated rate of 2.15 pg/mL per week.
• Serum NGMN levels showed no significant change over the 12-week continuous use period.
• Common side effects included vaginal spotting, breast tenderness, and abdominal discomfort; no serious adverse events were reported.

Conclusions:

• Continuous contraceptive patch use results in a slow, low-level accumulation of EE2, generally within product labeling ranges.
• While NGMN levels remain stable, the observed EE2 accumulation suggests caution.
• Extended continuous use beyond 12 weeks is not recommended without additional safety data.