Home : Next Page : Next Page : Current Page
Clomiphene Citrate
Clomiphene citrate is very commonly used in patients with a problem ovulating and in some patients as an empirical fertility enhancer.
There are three different brands of clomiphene citrate- clomid, serophene, and generic. The brands do not appear to differ from each other in efficacy. Price also seems to have more to do with the pharmacy from which the drug is purchased than the particular brand. The generic is available at some pharmacies for as low as $4/ treatment cycle.
Clomiphene works by blocking estrogen receptors. In the human, FSH, the pituitary hormone that stimulates egg and follicle development, is very tightly regulated. FSH is higher in the beginning of the first half of the cycle than at the end. As the follicle develops, estrogen is produced and causes the estrogen receptors in the pituitary to have less FSH produced. Larger follicles can get by on smaller amounts of FSH while smaller follicle wither away. (This is why a woman only ovulates one egg a month.) Clomiphene blocks this feedback signal and the amount of FSH stays high and it continues to cause follicle development. Some women, who otherwise would not ovulate, ovulate with clomiphene. Some women produce multiple follicles on clomiphene.
Clomiphene blocks estrogen receptors everywhere including in the cervix and in the uterus. The impact of this may be undesirable from a fertility standpoint and is dose related. That is why we use as low a dose as we can get by with and we seldom use clomiphene alone. Because of potential side-effects of clomiphene on fertility (and the costs and time associated with assessing if a patient has these side-effects), we use it with other medications such as HCG and gonadotropins and with IUI to compensate for these side effects. Letrozole works similarly, but has less fertility related negative side-effects.
Clomiphene is sometimes used to "enhance egg quality", because there is more FSH stimulation available for egg development. However, clomiphene does not increase the (peak) amount of FSH produced; it just enables the peak amount to be produced for a longer period of time. This is adequate for some applications, but for others, it is desirable to use FSH containing medications (gonadotropins) with or without clomiphene. Glucophage, bromocriptine, and dexamethasone all enhance the impact of clomiphene by improving the ovarian or systemic environment so that clomiphene works better.
Most infertility therapies, including clomiphene therapy, work in the first four to six cycles if they are going to work at all. Thus, patients should not be on clomiphene for a prolonged period of time. Clomiphene and its metabolic by-products also have a very long half-life. Some physicians feel that infertility-adverse side effects of clomiphene can be limited by taking a break from clomiphene after four cycles.