Contraceptive efficacy of once-weekly oral administration of 2.5 mg R 2323

Mechanism of emergency contraception with gestrinone: a preliminary investigation

BACKGROUND

A previous investigation showed that among 120 healthy women treated with a single oral dose of gestrinone for emergency contraception (EC), there was only one pregnancy. The effect of a single oral dose of gestrinone given for EC on ovarian function and endometrial development was studied.

STUDY DESIGN

Healthy fertile women were randomly assigned to Group A (n=8) or Group B (n=7). Gestrinone 5 mg was orally administered to each woman before (Group A) or after (Group B) ovulation. The day of ovulation was determined by transvaginal ultrasound and by urinary luteinizing hormone (LH) measured by enzyme immunoassay (One Step LH Ovulation Test). An endometrial biopsy was performed during implantation. Endometrial maturation and expression of markers of endometrial receptivity were analyzed. The tested markers were integrins alpha(1)beta(1), alpha(4)beta(1) and beta(3). Serum estradiol (E(2)) and progesterone (P) levels in serum were determined by radioimmunoassay, and estradiol receptors and progesterone receptors (PRs) in the endometrium were assessed by immunohistochemistry.

RESULTS

Gestrinone administered during the periovulatory period did not affect follicular development, ovulation, menstrual cycle length and E(2) and P levels but decreased the expression of PR in the endometrium. Integrin alpha(4)beta(1) tended to increase after treatment with gestrinone without reaching statistical significance.

CONCLUSION

The mode of action of gestrinone used for EC is probably inhibition of implantation by acting on the endometrium rather than inhibition of ovulation.

Evaluation of histological and ultrastructural aspects of endometrium during treatment with gestrinone in women with amenorrhea or spotting

Nineteen patients with a laparoscopic diagnosis of endometriosis were treated with gestrinone at a dosage of 2.5 mg twice a week for 6 months. In 7 who reported spotting in the first 3 months, the dose was increased to 2.5 mg three times a week during the second trimester. An endometrial sample was obtained from each patient at the time of laparoscopy (basal) and at 3 and 6 months of treatment. Endometrial structure and ultrastructure were studied. Areas of hemorrhage and of loss of surface epithelium and a lesser degree of involution of the surface epithelium were observed in the 3-month samples of 7 patients with spotting, compared with 12 with amenorrhea. It is hypothesized that incomplete endometrial involution could be due to differences in gestrinone pharmacokinetics in individual patients, in the quality and/or quantity of endometrial cytosolic receptors for sex steroids, or in endocrine compensation to administration of the drug.

Interaction of antiprogestins with progesterone receptors in rat uterus

Cytosolic and nuclear progesterone receptors (PRc and PRn) under antiprogestin treatment were measured in rat deciduoma and compared with values for contralateral (nondeciduomatous) rat uterine tissue. Uterine PRc and PRn of the progesterone treated group were 101 +/- 8.7 and 4770 +/- 590 fmol/mg DNA respectively. After treatment with antiprogestins STS-557, 5 alpha-DNE, (5 alpha-dihydronorethisterone), 5 alpha-DNG (5 alpha-dihydronorgestrel), RU-22092 and RU-16556, PRc in the nondeciduomatous control horn ranged from 127 to 377 fmol/mg DNA and PRn from 2785 to 17925 fmol/mg DNA. In the decidual tissue, PRc decreased significantly (4.6 +/- 0.8 fmol/mg DNA) on 5 alpha-DNG treatment as compared with the progesterone alone treatment group (147 +/- 3.8). PRn in decidual tissue also decreased maximally on 5 alpha-DNG treatment. These results suggest that the interaction of antiprogestins may not be identical in control uterine tissue and in deciduoma.

The response of human endometriotic implants to the anti-progesterone steroid R 2323: a histologic and ultrastructural study

The histology and ultrastructure of small endometriotic lesions were studied in 19 patients before and after hormonal therapy with the anti-progesterone steroid R 2323 (Gestrinone). Histologic results demonstrate that treatment of endometriosis with this steroid does not result in complete elimination of the endometriotic foci, although glandular proliferation and secretion are arrested in most implants. The ultrastructural results indicate that this inhibition of proliferation and secretion is related to an enhanced activity of the lysosomal system in the epithelial cells of some endometriotic foci. In other implants, or even in other cells of the same foci, epithelial cells with only a small amount of supranuclear cytoplasm but lacking lysosomes may be found. The morphologic data demonstrate that the cellular involutionary response to the antiprogesterone drug Gestrinone involves an activation of the lysosomal system, an abortive apocrine secretion of cell remnants and finally, in some implants, an extrusion of individual epithelial cells. Since this involutionary process of endometriotic cells mimics the pre-menstrual lysosomal degradation in the endometrium, it is suggested that the competitive binding of the antiprogesterone Gestrinone to the progesterone receptors of endometriotic epithelium may cause a cellular progesterone withdrawal effect.

Arrest of folliculogenesis and inhibition of ovulation in the monkey following weekly administration of progestins

Studies were undertaken in the rhesus monkey to determine whether development of a dominant ovarian follicle could be repeatedly arrested by the administration of a progestin on day 7 of the menstrual cycle, and then every 7 days thereafter regardless of menstrual bleeding history. Progesterone (7.5 mg), norethisterone (1.5 mg), and 17 alpha-ethinyl-17 beta-methoxy-7 alpha-methyl-4-estren-3-one (1.0 or 1.5 mg) effectively inhibited ovulation when injected intramuscularly once a week for 8 weeks. Orally administered STS 557 (17 alpha-cyanomethyl-17 beta-hydroxy-4,9-estradien-3-one, 1.0 mg) also inhibited ovulation. Two structurally related steroids (17 beta-methoxy-4-estren-3-one, 1.0 mg; and 17 beta-methoxy-7 alpha-methyl-4-estren-3-one, 1.5 mg) did not inhibit ovulation when given intramuscularly at the indicated doses. Although weekly administration of certain progestins effectively arrested follicular development and inhibited ovulation in the primate, the treatment was accompanied by disturbances in menstrual bleeding patterns.

The effects of a once-a-week steroid contraceptive (R2323) on lipid and carbohydrate metabolism in women during three months of use

Forty-four women were prospectively evaluated with a 3-hour oral glucose tolerance test while they used a new weekly oral contraceptive drug, R2323. The blood tests were carried out before the drug was administered and again 3 months after its use. Both blood glucose and plasma insulin levels were measured. In the 40 women with a "normal" control glucose tolerance test, it was found that only the 1-hour blood glucose value was significantly elevated after 3 months of drug use and the plasma insulin values were unchanged. The tests of three of the four women with borderline abnormal to abnormal control test curves converted to normal with 3 months of treatment and that of one remained unchanged. The fasting plasma cholesterol and triglyceride levels were unchanged over the 3 months' time. These results suggest that this steroid contraceptive has no effect on lipid metabolism. It also has minimal adverse effects on normal carbohydrate metabolism and may possibly improve abnormal metabolism.