Summary & Conclusion
Approximately 8-12% of women in general population have PCOS syndrome but it is the cause in about 30% of women with infertility.
Clomiphene citrate (CC) is the most commonly used oral agent for ovulation induction in this group, but there are some drawbacks with the use of it as it causes long lasting estrogen receptor depletion which have an adverse effect on the cervical mucus and endometrium in 15– 50% of patients causing higher incidence of miscarriage. In addition to increased risk of multiple pregnancies and ovarian hyper stimulation syndrome (OHSS), also, clomiphene resistance occurs in 15–20% of patients and is not predictable before beginning the treatment.
Recently, the new aromatase inhibitor, letrozole has been used for induction of ovulation. Letrozole reversibly inhibits the enzyme responsible for estrogen biosynthesis. By decreasing the estrogen levels in the body, it may release the hypothalamus and/or pituitary from the negative feed back of estrogen on the release of gonadotropins. This will result in an increase in end. However, Letrozole may have another peripheral mechanism of action directly in the ovaries. Letrozole is eliminated from the body in a few days after last administration (in contrast to CC which may last up to few months). Also, it does not have a direct antiestrogen action by itself as in CC. So there should be no unwanted peripheral antiestrogen effects on the endometrium, and the cervix. Letrozole (Femara®, Novartis) is available in 2.5 & 5 mg tablets. It is an approved drug that was developed to inhibit the estrogen production in postmenopausal women with breast cancer. Therefore, it has been tested and tolerated very well when administered continuously
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for several months.ogenous FSH and LH, which stimulate the development of ovarian follicles.
Letrozole is associated with thicker endometrium favorable cervical mucous and better uterine blood flow
The present study was done to compare the efficacy of Short course (5mg daily for 5 days) Vs extended course (2.5mg daily for 10 days) of letrozole therapy for ovulation induction in women with polycystic ovary syndrome.
The study included 40 patients who are attending Benha Hospital and previously diagnosed as having polycystic ovary syndrome. Patients were divided randomly into 2 treatment groups, short letrozole therapy group (20 patients) and long letrozole therapy group (20 patients).
Patients of short letrozole therapy group received 5mg of letrozole daily starting from day 1 menstrual bleeding for 5 days. Patients of long letrozole therapy group received 2.5mg of letrozole daily starting from day 1 of menstrual bleeding for 10 days.
All patients of both groups monitored by trans-vaginal ultrasound for the mean follicular volume and thickness of the endometrium on day 10 of the cycles.
hCG injection (5,000 IU IM) given when at least one follicle measured ≥ 18mm. Patients advised for intercourse 24- 36h after HCG injection.
Serum hCG determined 2 weeks after hCG injection in the absence of menstruation for diagnosis of pregnancy followed by trans- vaginal ultrasound for demonstration of the gestational sac.
Summary & Conclusion
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The study results showed that total number of follicles during stimulation was significantly greater in the long letrozole group (4 ± 1) vs. (3 ± 1; p=>0.001) in short letrozole group. The mean of biggest follicles size (mm) was greater (18± 4) in the long letrozole group when compared to short letrozole group (17± 4), without statistical differences (p=0.476). The number of patients with follicles measuring >18 mm was greater (55%) in the long letrozole group without statistical significance (p=0.766). The mean of endometrial thickness at the time of HCG administration was (8± 2) in the long letrozole group similar to short letrozole group (8 ± 2) without significant difference (p=0.713). The pregnancy was greater (25%) in the long letrozole group when compared to short letrozole group (15%), with no statistical differences (p=0.695). |
