Clomiphene Citrate Actions
Clomiphene Citrate acts as a competitive inhibitor at oestrogen-receptors blocking their activation by endogenous oestrogen. Clomiphene Citrate competes with oestrogen on binding sites at hypothalamic level in which gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone secretion are increased. These increase results in the maturation of the ovarian follicle and thus, the development and function of the Corpus luteum.
Take Clomiphene Citrate only as directed by your doctor. If you are to begin on Day 5, count the first day of your menstrual period as Day 1. Beginning on Day 5, take the correct dose every day for as many days as your doctor ordered. To help you to remember to take your dose of medicine, take it at the same time every day.
The dose of Clomiphene Citrate will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of Clomiphene Citrate. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
If you miss a dose of Clomiphene Citrate, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
If you do not remember until it is time for the next dose, take both doses together; then go back to your regular dosing schedule. If you miss more than one dose, check with your doctor.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
The total daily dose should be taken at one time to maximize effectiveness (Dickey, 1996).
Clomiphene Citrate tablets USP is a drug of considerable pharmacologic potency. With careful selection and proper management of the patient, Clomiphene Citrate tablets USP has been demonstrated to be a useful therapy for the anovulatory patient desiring pregnancy.
Clomiphene Citrate is capable of interacting with estrogen-receptor-containing tissues, including the hypothalamus, pituitary, ovary, endometrium, vagina, and cervix. It may compete with estrogen for estrogen-receptor-binding sites and may delay replenishment of intracellular estrogen receptors. Clomiphene Citrate initiates a series of endocrine events culminating in a preovulatory gonadotropin surge and subsequent follicular rupture. The first endocrine event in response to a course of Clomiphene Citrate therapy is an increase in the release of pituitary gonadotropins. This initiates steroidogenesis and folliculogenesis, resulting in growth of the ovarian follicle and an increase in the circulating level of estradiol. Following ovulation, plasma progesterone and estradiol rise and fall as they would in a normal ovulatory cycle.
Available data suggest that both the estrogenic and antiestrogenic properties of Clomiphene Citrate may participate in the initiation of ovulation. The two Clomiphene Citrate isomers have been found to have mixed estrogenic and antiestrogenic effects, which may vary from one species to another. Some data suggest that zuClomiphene has greater estrogenic activity than enClomiphene.
Clomiphene Citrate has no apparent progestational, androgenic, or antiandrogenic effects and does not appear to interfere with pituitary-adrenal or pituitary-thyroid function.
Although there is no evidence of a "carryover effect" of Clomiphene Citrate tablets USP, spontaneous ovulatory menses have been noted in some patients after Clomiphene Citrate tablets USP therapy.
Based on early studies with 14C-labeled Clomiphene Citrate, the drug was shown to be readily absorbed orally in humans and excreted principally in the feces. Cumulative urinary and fecal excretion of the 14C averaged about 50% of the oral dose and 37% of an intravenous dose after 5 days. Mean urinary excretion was approximately 8% with fecal excretion of about 42%.
Some 14C label was still present in the feces 6 weeks after administration. Subsequent single-dose studies in normal volunteers showed that zuClomiphene (cis) has a longer half-life than enClomiphene (trans). Detectable levels of zuClomiphene persisted for longer than a month in these subjects. This may be suggestive of stereo-specific enterohepatic recycling or sequestering of the zuClomiphene. Thus, it is possible that some active drug may remain in the body during early pregnancy in women who conceive in the menstrual cycle during Clomiphene Citrate tablets USP therapy.
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Information checked by Dr. Sachin Kumar, MD Pharmacology