Effects of intranasal administration of norethisterone on folliculogenesis, cervical mucus, vaginal cytology, endometrial morphology and reproductive-endocrine profile in women

Abstract

The effects of intranasal administration of norethisterone (NET) on menstrual cycle length, folliculogenesis, serum levels of estradiol, FSH, LH and progesterone, vaginal cytology, cervical mucus and endometrial morphology were studied in 8 volunteers (age 28 to 39 years, weighing between 46 to 54 kg). The study period comprised 4 consecutive menstrual cycles. In the first cycle (pretreatment cycle), only the vehicle (alcohol, propylene glycol, water; 3:3:4) was sprayed intranasally (100 μl in each nostril), using a metered nebulizer, once daily from day 3 to the last day of menstrual cycle. In the next two cycles (treatment cycles), NET (300 μg/day) was administered once daily, starting from day one of menstrual cycle, between 9 and 10 a.m. The fourth cycle was a post-treatment cycle in which the volunteers were monitored for recovery. Blood samples (about 5 ml each) were collected once daily from day 8 to 24 and thereafter on alternate days until the last day of cycle during all the 4 cycles. Levels of estradiol, FSH, LH and progesterone were measured in the serum samples by radioimmunoassay methods. Cervical mucus samples and vaginal smears were collected once daily starting from day 7 or 8 of each cycle until the mucus was very scanty. Serial pelvic ultrasonography was performed starting from day 7 or 8 until the growing follicle disappeared or throughout the cycle in case a growing follicular cyst was observed. Endometrial aspirates were collected once around day 22 in each cycle and processed for routine histological examination. Intranasal administration of NET had no significant effect on mean menstrual cycle length. However, other parameters were affected in a significant number of treatment cycles. The mean cervical mucus score of 13.5 in pretreatment cycle was reduced significantly in 5 and 6 volunteers in the first and second treatment cycles, respectively, and in the others it was not affected. In 10 treatment cycles the vaginal cytology was indicative of anovulation and in one each it was inconclusive and ovulatory. Since in 2 volunteers the vaginal smears during the pretreatment cycles were not indicative of ovulatory cycles, it was considered that their vagina were probably refractory to hormonal changes and were thus not considered for purposes of evaluating the effects of NET on vaginal cytology. On the basis of endocrine profile, 8 cycles showed ovulatory pattern in which progesterone levels were indistinquishable from pretreatment cycle, 5 cycles were anovulatory and the remaining 3 were deficient in progesterone and had longer follicular phase and shorter luteal phases. Ultrasonographic evidence of normal folliculogenesis and ovulation was observed in 7 cycles. Formation of follicular cysts was seen in 8 treatment cycles of which 7 were anovulatory and in one ovulation was observed in the contralateral ovary. The size of the cysts varied between 29 to 44 mm. The cysts disappeared either just before the menses in the same cycle or by the middle of post-treatment cycle. A positive correlation (r = 0.679) in the size of follicular cyst with estradiol levels was observed. In two cycles normal folliculogenesis was observed; however, the follicle did not rupture at the anticipated time. Since these two cycles had normal estradiol and progesterone levels, these were classified to have luteinized unruptured follicles. Out of 11 samples of endometrial aspirates, which could be collected during two treatment cycles, hormonal effects were seen in 10 and in one the endometrium was secretory. In 5 cycles where the aspirates could not be collected, it is possible that the endometrium was either very scanty or had undergone atrophy. These observations, therefore, provide convincing evidence that NET administered intranasally causes changes both in the reproductive endocrine parameters as well as on the end organs and that these changes are suggestive of antifertility effects.