In situations where treatment with Clomiphene Citrate does not work, the use of medicines containing gonadotropins, which are hormones that act by stimulating the ovaries directly, promoting follicular development and oocytes, may be necessary.
The gonadotropin hormones used in the treatment of infertility can be urinary (extracted and purified from the urine of postmenopausal women) or recombinant (synthesised in the laboratory by applying biotechnology techniques).
The two main gonadotropins are follicle stimulating hormone (FSH) and luteinizing hormone (LH), so called because they exert their effects mainly on the ovaries and testes (also called gonads).
In women, FSH and LH exert complementary but separate actions: The growth and development of ovarian follicles and the synthesis and secretion of important ovarian hormones, such as oestrogens and progesterone.
FSH stimulates follicle development, whereas LH is the most important hormone in the luteal phase. Decreases or imbalances in the levels of LH and FSH can lead to situations such as anovulation (no ovulation) and infertility. In the presence of high levels of intratesticular androgens, FSH induces spermatogenesis (sperm production).
The gonadotropins are administered by injection and are the most common drugs used to treat infertility in modern day. When the ovaries are properly developed, an injection of the hormone hCG (human chorionic gonadotropin) is administered to trigger the ovulation process and the subsequent release of an oocyte. These type of drugs are used to stimulate ovulation in IUI cycles, IVF and ICSI treatment cycles or timed intercourse.