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Postcoital contraception.

The evolution of postcoital contraception has led to the development of emergency measures to be used following a single unprotected act of intercourse and to ongoing methods, such as the administration of a contraceptive steroid agent following every coital exposure. In emergency situations, the most commonly employed hormonal steroids are the synthetic, conjugated and natural estrogens, administered in large doses for five days. Recently, a combination of an estrogen and a progestin has been employed for the same purpose. A copper-bearing intrauterine device (IUD), inserted within seven days of coitus, has also been utilized with success. Progestins alone have been utilized as an ongoing method of postcoital contraception. Failure rates have been found to vary with the dosage, the specific progestin employed and the frequency of intercourse. The major role of postcoital contraception in the developed world appears to be as an emergency measure. Ease of availability, a high degree of efficacy and a low incidence of side effects are essential for patient and physician acceptance.

Animals↗
PubMed1978

The anti-reproductive pharmacology of LH-RH and agonistic analogues.

LH-RH and three particular ("super") analogues were evaluated for agonistic (ovulation-induction and short-term uterotrophic properties) and postcoital contraceptive activity in rodents. Additionally, LH-RH and/or a representative analogue (D-Ala6-des Gly10-Pro9-LH-RH ethylamide) were tested for postcoital contraceptive/vaginal smear/return to fertility effects, precoital contraceptive activity, and effects on puberty in the immature female. All compounds induced ovulation and uterotrophic effects and terminated pregnancy when administered either pre- or post-implantation. LH-RH and the representative analogue, while terminating pregnancy postcoitally, produced an associated break in the characteristic leucocytic vaginal smear of pregnancy to one of cornification by day 12; at this time mating and insemination were reestablished and all rats carried to normal term. Precoitally, LH-RH administered to nembutalized (but not to unblocked) rats produced a 50% reduction in the pregnancy rate and a 38% decrease in the number of viable pups delivered. In immature rats, the representative analogue delayed puberty (i.e. vaginal canalization) and retarded the growth of the ovaries, uteri, and anterior pituitary gland. The collective data strongly support the concept that LH-RH and agonistic derivatives, in spite of their putative pro-fertility classification, are characteristically antifertility by nature. Since the latter effect appears to be the paradoxically dominant one, it is suggested that LH-RH agonism is synonymous with contraception. Furthermore, such peptides may represent a new potential approach to fertility control.

Animals↗
PubMed1975

[Study of the mechanism of postcoital contraception in the combination of streoids and the central m-cholinolytic, amizil].

Experiments on female rats showed the blocking of the M-cholinoreactive system with amizyl to significantly contribute to the estrogen/norsteroid contraceptive effect during the postcoital periods. This effect was accompanied by decrease in the gonadotropin level and by the change in the LH/FSH ratio, this creating an unfavourable background for implantation of the fertilized ovicell in the endometrium. There was a change in the transport rate in the tube and a delay in the decidual reaction. Changes in the rate of the ovicell transport were not accompanied by distrubances in the process of fertilization or with the cytotoxic action. Mestranol and ethynylestradiol in combination with norethynodrel (1:20) and with the central cholinolytic amizyl were agents with future prospects for short-term postcoital contraception.

Animals↗
PubMed1977

Postcoital contraceptive effects of agonist analogs of luteinizing hormone-releasing hormone.

Various analogs of synthetic hypothalamic luteinizing hormone-releasing hormone (LH-RH) were evaluated for agonistic (ovulation-inducing), postcoital contraceptive, and direct uterotrophic activities. All analogs showing agonistic activity also possessed the ability to terminate pregnancy, as did LH-RH; there appeared to be a direct relationship between agonistic and postcoital potency and activity. The highly potent and active LH-RH agonist, D-[Ala]6-des-[Gly]10-pro9-ethylamide-LH-RH, proved to be the most potent and active postcoital preimplantational and postimplantational antifertility agent. In contrast to LH-RH, none of the analogs tested in the hypophysectomized animal produced a uterotrophic effect, revealing a selective extrapituitary effect of the parent hormone. The collective data demonstrate that peptides derived from LH-RH and bearing agonistic properties can terminate pregnancy postcoitally, via disruption of the pituitary-ovarian reproductive complex. Possible mechanisms are discussed, and the use of members of this neurohormonal class as potential profertility agents should be weighed with caution.

Animals↗
PubMed1976

Luteinizing hormone and progesterone in women under postcoital contraception with D-norgestrel.

Luteinizing hormone (LH) and progesterone (Pg) levels in blood were measured simultaneously by radioimmunoassay during 53 menstrual cycles in order to investigate the effect of 400 mug of D-norgestrel, administered postcoitally, on pituitary and ovarian function. Of 31 control cycles, 2 appeared to be anovulatory, since the LH peak and subsequent Pg elevation were absent. Twenty-nine cycles showed typical LH surges in the middle of the cycle, followed by a manifold Pg increase. Twelve women received 5 to 13 tables of D-norgestrel. A total absence or at least marked suppression of LH and Pg elevations was observed. In a third group, D-norgestrel was administered on scheduled days. Each woman ingested one to four tablets between the 6th and 18th days of the cycle. Two or more tablets disturbed LH and Pg ovulatory patterns. Of four women who received a tablet on day 10, one failed to show characteristic ovulatory patterns and three exhibited a delay in the time of the LH and Pg increase. These results demonstrate that D-norgestrel in a postcoital regimen alters pituitary and ovarian function, strongly suggesting an antiovulatory effect.

Contraceptives, Postcoital↗