Kilic-Okman, T., Kucuk, M., & Altaner, S. (2003). Comparison of the effects of letrozole and clomiphene citrate on ovarian follicles, endometrium, and hormone levels in the rat. Fertility and Sterility, 80(6), 1330-1332. https://doi.org/10.1016/j.fertnstert.2003.05.002
Kilic-Okman T, Kucuk M, Altaner S. Comparison of the effects of letrozole and clomiphene citrate on ovarian follicles, endometrium, and hormone levels in the rat. Fertil Steril. 2003;80(6):1330-1332. doi:10.1016/j.fertnstert.2003.05.002
Kilic-Okman, Tulay, et al. "Comparison of the effects of letrozole and clomiphene citrate on ovarian follicles, endometrium, and hormone levels in the rat." Fertility and Sterility, vol. 80, no. 6, 2003, pp. 1330-1332.
For EndNote, Zotero or Mendeley:
License
No open license is recorded for this paper. Reuse terms are set by the publisher.
Letrozole and clomiphene stimulate similar follicle growth in rats
Letrozole raised mature follicle counts in rats to a level similar to clomiphene citrate, in a controlled prospective study of 30 female rats in three groups of 10. Both drug groups had more mature follicles than the saline group. Endometrial thickness was similar in all three groups.
Key Findings
Mature follicle counts averaged 29.10 with letrozole, 27.60 with clomiphene citrate and 25.00 with saline. Follicle counts did not differ significantly between the letrozole and clomiphene citrate groups.
Ovary size was larger in both drug groups than in the saline group and did not differ significantly between letrozole and clomiphene citrate.
Estradiol was lower with letrozole than with clomiphene citrate or saline, and testosterone was higher with letrozole than with either. Clomiphene citrate and saline did not differ on estradiol or testosterone.
Endometrial thickness averaged 0.80 mm with letrozole, 0.80 mm with clomiphene citrate and 1.0 mm with saline, with no significant difference among the groups.
Interpretation
The authors report the first controlled prospective comparison of the two drugs in rats. Dosing lasted 2 days in 30 cycling rats, 10 per group. A pathologist unaware of group assignment read the tissue sections. Outcomes measured were mature follicle number, ovary size, endometrial thickness and serum hormone levels. The authors note that clomiphene citrate at the dose used may have blocked estrogen action or production. The findings support further study of letrozole for ovulation induction.
RRM Context
The paper calls clomiphene citrate the most commonly prescribed drug for inducing ovulation and tests letrozole as a candidate. Restorative reproductive medicine starts by finding why a woman is not ovulating. That evaluation comes before any drug choice. Animal studies of how a drug acts on the ovary add to that picture.
Our editorial summary of this paper, not the article's abstract.
Abstract
Objective
To compare the effects of letrozole and clomiphene citrate in the rat in terms of number of ovarian follicles; endometrial thickness; and serum levels of E2, FSH, LH, and T.
Design
Controlled prospective study.
Setting
University research laboratory.
Animals
Thirty sexually mature female Wistar-Albino rats that were 20 weeks of age.
Interventions
Letrozole, 5 mg/kg of body weight daily (10 rats); clomiphene citrate, 100 microg/kg daily (10 rats); or saline solution, 2 mL/d (10 rats). After 2 days, rats were euthanized and ovariectomized.
Main Outcome Measures
Number of mature follicles, endometrial thickness, and serum levels of hormones.
Results
Mean levels of FSH, LH, E2, and T; number of mature follicles; and ovary size differed among the groups, whereas the mean endometrial thickness did not differ.
Conclusions
In rats, the effect of letrozole on follicular maturation is similar to that of clomiphene citrate.
00xa0xn82 