Saturday, September 19, 2009

Drugs Used For Anovulation
This list also comprises most of the drugs used for ovulation induction and IVF treatments

The medication which is most commonly used to treat anovulation is clomifene citrate
(or clomid), which has been used since the 1960s. It was first used to treat cases of oligomenorrhea, and it was then applied to the treatment of anovulation. It is relatively easy and convenient to use: factors which contributed to its success. Clomifene citrate has an anti-estrogenic role, and it appears to stimulate the pituitary and therefore affect the ovarian function.It also has an effect on cervical mucus quality and uterine mucosa, which might affect sperm penetration and survival, hence its early administration during the menstrual cycle. Clomifene citrate is a very efficient ovulation inductor, and has a success rate of 67%. Nevertheless, it only has a 37% success rate in inducing pregnancy. This difference may be due to the anti-estrogenic effect which clomifene citrate has on the endometrium, cervical mucus, uterine blood flow, as well as the resulting decrease in the motility of the fallopian tubes and the maturation of the oocytes.
  • Another anti-estrogenic molecule called tamoxifen is often used in the prevention and treatment of breast cancer. It can therefore also be used to treat patients that have a reaction to clomifene citrate. A third anti-estrogenic compound
  • Femara (Letrozole) is used also as a substitute for Clomid . Estrogens are produced by the conversion of androgens through the activity of the aromatase enzyme. Letrozole blocks production of estrogens in this way by competitive, reversible binding to the heme of its cytochrome P450 unit. The action is specific, and letrozole does not reduce production of mineralo- or corticosteroids. In contrast, the antiestrogenic action of tamoxifen, the major medical therapy prior to the arrival of aromatase inhibitors, is due to its interfering with the estrogen receptor, rather than inhibiting estrogen production.
  • Human chorionic gonadotropin (hCG) is a molecule which is structurally similar to luteinizing hormone (LH). LH is secreted by the pituitary just before ovulation occurs, whereas hCG is released during pregnancy. On its own, hCG is not very effective in inducing ovulation, but when combined with clomifene citrate, it is much more effective. HCG should only be administered at certain points in the cycle, around the time of ovulation. A Recombinant version of hCG is available commercially and it is called Ovidrel. Ovidrel works just like hcg but it si more convenient because it does not require mixing.
  • Human menopausal gonadotropin (hMG) is a very powerful treatment for infertility. It consists of a combination of LH and FSH. From menopause onwards, the body starts secreting LH and FSH in large quantities due to the slowing down of the ovarian function. This excess of hormones is not used by the body and is expelled in the urine. HMG is therefore collected from the urine of menopausal women. The urine then undergoes purification and a chemical treatment. The resulting hMG induces the stimulation of several ovarian follicles. This increases the risk of producing several oocytes during the same cycle, and thus the risk of multiple pregnancies. Commercial names of hMGs are Menopur, Repronex.
  • Follicle-stimulating hormone (FSH or recombinant FSH) is now used as a replacement for hMG. Although hMG is a combination of FSH and LH, FSH is the main active component that has an effect on ovulation.
  • Metformin is an oral biguanid used to treat type 2 diabetes that has shown very promising results in the treatment of patients with PCOS. However, some experts question the efficacy of metformin. Though the results from early treatment with metformin were promising, its role and the roles of other similar molecules in reducing insulin levels among patients suffering from PCOS is not very clear.
  • Several studies indicate that in some cases, a simple change in lifestyle could help patients suffering from anovulation. Consulting a nutritionist, for example, could help a young women suffering from anorexia to put on some weight, which might re-start her menstrual cycle. Conversely, a young overweight woman who manages to lose weight could also relieve the problem of anovulation (losing just 5% of body mass could be enough to re-start ovulation). However, it is widely acknowledged by doctors that it is usually very difficult for PCOS patients to lose weight.
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