Five-year, multicenter study of a triphasic, low-dose, combination oral contraceptive

Area of Science:

• Reproductive Health
• Pharmacology
• Contraception

Background:

• Oral contraceptives are widely used for family planning.
• Triphasic formulations aim to mimic natural hormonal fluctuations.
• Assessing the efficacy and tolerability of specific oral contraceptive formulations is crucial.

Purpose of the Study:

• To evaluate the efficacy and tolerability of a specific triphasic oral contraceptive containing levonorgestrel and ethinyl estradiol.
• To determine the Pearl Index (PI) and corrected PI for this contraceptive formulation.
• To assess cycle control and adverse experiences associated with its use.

Main Methods:

• A 5-year prospective study involving 4,342 women and 70,282 cycles.
• Administration of a triphasic oral contraceptive with specific dosages of levonorgestrel (LNg) and ethinyl estradiol (EE2).
• No backup contraception was used; medication initiation was on day 1 of the first cycle.

Main Results:

• A total of 12 pregnancies occurred, yielding a Pearl Index of 0.22.
• Misuse of the drug was reported in 7.2% of cycles, with 9 pregnancies attributed to misuse.
• A corrected Pearl Index of 0.06 was calculated, indicating high efficacy with correct usage.
• Excellent cycle control, minimal bleeding irregularities, and a low incidence of adverse experiences (<1% of cycles) were observed.

Conclusions:

• The triphasic oral contraceptive containing levonorgestrel and ethinyl estradiol is a predictable and efficacious method of contraception.
• The formulation is well-tolerated and accepted by users.
• Pharmacologic doses patterned after normal cycles contribute to its effectiveness and tolerability.