Ovulation Induction

What is Ovulation Induction And Ovarian Stimulation?

Ovulation Induction refers to the therapeutic restoration of the release of one egg per cycle in a woman who is not ovulating at all or ovulating irregularly. It differs from Ovarian Stimulation where we aim to have multi-follicular development, especially in unexplained infertility. Ovulatory disturbances are present in about 15 – 25% of infertile couples and the majority of these women have polycystic ovaries.

What are the various Ovulation Induction Drugs?

• Insulin Sensitizers like Metformin or Myoinositol
• Clomiphene Citrate
• Aromatase Inhibitors
• Gonadotropins

Description of Drugs

• Insulin Sensitizers: Weight reduction either by lifestyle modification or by insulin sensitizers like metformin or myoinositol constitutes the first and foremost modality in obese patients to restore ovulation followed by other therapeutic drugs like Clomiphene Citrate.
• Clomiphene Citrate: It’s the first line and most ubiquitously used drug for ovulation in PCOS patients. It’s a weak synthetic estrogen, with antiestrogenic properties. It is usually given in a starting dose of 50- 100 mg, from day 2/3/5 of the cycle for 5 days. Ovulation is expected to occur 7-10 days after the last tablet in 80- 85% of treated women and 40% conceive. Side effects are usually mild and usually occur in the form of hot flushes, abdominal distention, bloating, nausea, vomiting, and headache. This drug is safe, cheap, easy to administer, and highly effective for ovulation induction.
• Aromatase inhibitors (Letrozole, Anastrozole): 20-25 % of women are resistant to clomiphene citrate and do not ovulate. Aromatase inhibitors(AI) originally developed and approved for the treatment of breast cancer are currently being used as an alternative to clomiphene with increased frequency. Letrozole is a third-generation aromatase inhibitor (AI). The AI, letrozole, is effective in ovulation induction in women with PCOS resistant to clomiphene citrate and ovarian stimulation for intrauterine insemination and in vitro fertilization (IVF). Letrozole is an attractive option with its oral route of administration, cost, safety profile, and effectiveness in ovulation induction and ovarian stimulation. Letrozole gives comparable ovulation, pregnancy, and miscarriage rates to clomiphene.
• Gonadotrophins: May be used to stimulate follicular development and induce ovulation. They may be used for PCOS women who have failed to respond to oral drugs like Clomiphene Citrate or Letrozole. They are also used for Controlled Ovarian Stimulation, especially when combined with IUI in unexplained infertility. Gonadotrophin treatment requires daily injection with either HMG, Urinary FSH or Recombinant FSH. Gonadotropins require intensive follicle monitoring by Ultrasound and to be supplemented with serum Serum Estradiol levels when required. The pregnancy rates are better than clomiphene citrate but the cost increases and there are increased chances of multiple pregnancies and OHSS.