Purpose
Fertility drugs are given to stimulate the ovaries so that they produce mature egg containing follicles. In a normal menstrual cycle, one follicle (occasionally more) matures and releases an egg. Fertility medications often stimulate the production of many follicles, so that there's a greater chance of at least one egg being fertilized. Fertility drugs are most often given in conjunction with assisted reproductive technology (ART), such as in vitro fertilization or intrauterine insemination.
Mechanisms
The first drug used in fertility treatment is often clomiphene citrate, or Clomid. Clomid stimulates ovulation in anovulatory women or helps the ovary create a more mature follicle. Clomid fools the body into thinking that it's not producing enough estrogen. This prompts the hypothalamus to produce more gonadotropin-releasing hormone, or GnRH, which increases the release of follicle stimulating hormone (FSH). FSH encourages the ovary to produce estrogen, so that a follicle matures. Clomid is given in the first half of the menstrual cycle, usually for five days, then stopped.
If Clomid isn't doing the job, or if a couple moves to in vitro fertilization, fertility drugs called gonadotropins are given. This is called controlled ovarian hyperstimulation, or COH. Gonadotropins are hormones that stimulate the ovaries directly. Gonadotropins contain either pure FSH, or FSH plus a small amount of luteinizing hormone (LH). Gonadotropins must be given by injection because they break down in the stomach and aren't properly absorbed.
LH and FSH work on the ovaries in different ways. LH causes the theca cells in the ovary to release testosterone, which is then converted into estrogen. FSH stimulates follicles to mature in the ovary.
Administration
There are several types of gonadotropins on the market in 2009. Two are synthetically created man made forms of pure FSH: Gonal F and Follistim. These drugs can be injected subcutaneously, because they contain no animal proteins that irritate tissue.
Bravelle is highly purified FSH, with LH removed; it's made from the urine of postmenopusal women. Bravelle is also given subcutaneously. Repronex is a mixture of LH and FSH made from postmenopausal women's urine; some doctors give the drug subcutaneously. Menopur is a more purified form of Repronex and can be given subcutaneously. The recombinant (made in the lab) gonadotropins are most expensive.
Some gonadotropins are sold in prefilled pens that can be programmed to deliver a specific amount of the drug. A study reported at the annual meeting of the Pacific Coast Fertility Society meeting in 2006 noted that egg donors using gonadotropin pens needed less medication and tolerated the injections better.
The most serious risk for patients using gondotropins, according to the American Society for Reproductive Medicine, is ovarian hyperstimulation syndrome, where the ovaries become painfully swollen.
References
- A retrospective comparison of clinical outcomes and satisfaction using reconstituted recombinant gonadotropins (rFSH) or cartridge rFSH with a pen device in donor oocyte cycles; M.S. Christianson et al ; 2006
- Medications for Inducing Ovulation: A Patient's Guide; American Society for Reproductive Medicine
