Clinical evaluation of injectable biodegradable contraceptive system

Area of Science:

• Reproductive endocrinology
• Pharmacology
• Biomaterials science

Background:

• Long-acting injectable contraceptives are crucial for family planning.
• Biodegradable microsphere technology offers sustained drug delivery.
• Norethisterone (NET) is a progestin used in hormonal contraception.

Purpose of the Study:

• To evaluate a novel long-acting injectable contraceptive system using norethisterone (NET) microspheres.
• To determine the effective dosage for ovulation suppression and its impact on menstrual bleeding.
• To assess the safety and tolerability of the NET microsphere system.

Main Methods:

• A Phase I clinical trial involving 24 women.
• Administration of biodegradable d,l-polylactic acid microspheres containing micronized NET.
• Monitoring of serum NET, estrogen, and progesterone levels via radioimmunoassay.
• Evaluation of ovarian function and menstrual bleeding patterns.

Main Results:

• Sustained NET release for 6 months, with serum levels proportional to dose.
• Doses below 0.267 mg NET/kg had no effect on ovarian function or menses.
• Higher doses (0.419–2.30 mg NET/kg) showed variable effects, with increased doses suppressing ovulation and altering bleeding patterns.
• Optimal doses of 1.33–3.45 mg NET/kg were identified for 6-month ovulation suppression.

Conclusions:

• The NET-loaded biodegradable microsphere system is a promising long-acting injectable contraceptive.
• Specific dosage ranges are critical for achieving effective ovulation suppression and managing menstrual bleeding.
• The system was well-tolerated, with minor side effects like spotting and irregular cycles.