Reproductive Health Information
Fertility drugs are available to treat many of the conditions that cause infertility. Many of these fertility drugs, such as Clomid and FSH, are known as "ovulation inducing agents." A normal menstrual cycle involves follicular (egg) recruitment and growth, development of the endometrium,ovulation, fertilization, and implantation in the endometrium.
These processes are regulated by hormone relationships in the "hypothalamic-ovarain-pituitary axis (HPO)." Conditions that adversely affect the HPO axis can lead to anovulation (lack of ovulation) and infertility. Many fertility tests are available to help determine the cause of failed ovulation.
Fertility Drugs and Ovulation
Many fertility drugs work at the hypothalamus or pituitary gland to influence the production of FSH, LH, and other hormones. It is necessary to have a basic understanding of how the HPO axis functions in order to understand how these fertility drugs exert their actions.
The hypothalamus can be compared to a "thermostat" because it monitors the levels of hormones such as follicle stimulating hormone (FSH), luteinizing hormone (LH), estrogen, and others. As it monitors these hormones, it "balances" their levels. Fertility drugs such as Lupron and Ganirelix exert their effects by influencing the production of GnRH. During the first days of the menstrual cycle, the hypothalamus produces gonadotropin-releasing hormone (GnRH), which travels to the pituitary where it stimulates the release of follicle stimulating hormone.
Fertility drugs, such as Lupron and Ganirelex, inhibit GnRH production thus reducing the internal production of FSH and blocking the LH surge. Therefore, FSH must be administered by injection. FSH causes the recruitment of follicles, each of which contains an egg, and supports them as they mature. As the follicles grow they begin to produce estrogen, which travels through the bloodstream to the hypothalamus. Estrogen also stimulates the development of the endometrium.
Fertility drugs (FSH) like Gonal-F, Follistim, and Bravelle are administered during an IVF cycle to stimulate the recruitment and development of numerous eggs, needed for IVF. Unlike Clomid which works at the hypothalamus, FSH stimulates the ovaries directly.
Fertility drugs, such as Lupron and Antagon, influence the actions of GnRH allowing the physician to control the stimulation cycle, particularly when ovulation occurs. Rising levels of estrogen cause the hypothalamus to reduce its production of GnRH thus lowering FSH levels. Once the follicle(s) is mature, the hypothalamus signals the pituitary to release a surge of LH, which triggers ovulation.
Fertility drugs such as Pregnyl and Ovidrel are used in IVF cycles to stimulate ovulation since the effects of GnRH are blocked. These products have the same effect on ovulation as LH.
Fertility drugs such as FSH must be monitored to ensure proper follicular development and reduce the chance of side effects. The fertility specialist carefully adjusts the dose to insure follicular development and to time ovulation. In an in vitro fertilization cycle, ovulation must not occur prior to egg retrieval or the cycle would be "lost."
Lupron and Ganirelex are products that block the LH surge. A women usually will not ovulate as long as she receives one of these products. Once the physician judges that the follicles are mature, an injection of hCG (the fertility drugs Ovidrel, Pregnyl, or Luveris may be used) is given to mimic the natural LH surge and egg retrieval is scheduled.
Many fertility drugs are available to treat infertility:
- Clomid for ovulation induction.
- Gonal-F, Follistim, Bravelle, Menopur, Repronex for ovulation induction.
- Glucophage (metformin) may be used in the management of polycystic ovarian syndrome.
- Parlodel for hyperprolactinemia.
- Lupron or Ganirelix Acetate used to prevent premature ovulation in assisted reproductive technology cycles.
- hCG Ovidrel or Luveris used to stimulate ovulation 36 hours prior to egg retrieval in IVF procedures or 36 hours prior to insemination in IUI cycles. Luveris may also be prescribed for women with hypogonadotropic hypogonadism, which is extremely low levels of FSH and LH.
- Birth Control Pills may be prescribed to insure there are no "leftover follicles" from previous cycles.
- Antibiotics used to treat infection in the male and female.
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