Failure to interrupt established pregnancy in humans by D-tryptophan-6-luteinizing hormone-releasing hormone

Comparison of leuprolide acetate and triptorelin in assisted reproductive technology cycles: a prospective, randomized study

OBJECTIVE

To compare the use of two depot GnRH-a, leuprolide and triptorelin, in long-suppression GnRH-a protocols.

DESIGN

Prospective, randomized study.

SETTING

An IVF unit of an academic medical center.Fifty-two women who underwent controlled ovarian hyperstimulation and IVF.

INTERVENTION(S)

Patients were prospectively randomized to receive 3.75 mg depot formulations of either leuprolide or triptorelin on days 21-23 of the menstrual cycle. Stimulation with gonadotropins was initiated after pituitary desensitization was achieved.

MAIN OUTCOME MEASURE(S)

The stimulation pattern and cycle outcomes were compared between the two groups.

RESULT(S)

Twenty-six patients were included in each group. No significant differences were observed in the patient age, estrogen, and P levels on day of hCG administration, gonadotropin dosage, number of oocytes retrieved, fertilization rate, percentage of high-quality embryos, and number of embryos transferred. However, significantly higher clinical implantation and pregnancy rates were found in the leuprolide group compared with the triptorelin group.

CONCLUSION(S)

A depot preparation of leuprolide is associated with higher implantation and pregnancy rates than a depot preparation of triptorelin when it is used in the midluteal phase as part of the long-suppression GnRH-a protocol in IVF.

Should we still advise infertile couples to use (barrier) contraception before IVF down-regulation?

OBJECTIVE

To determine the outcome of spontaneous conceptions in women who received GnRH agonists during mid-luteal phase down-regulation before IVF treatment.

DESIGN

Retrospective analysis of case records and study of the literature.

SETTING

Two university-affiliated reproductive medicine units.

PATIENT(S)

Seventy-three women who conceived spontaneously after starting down-regulation with a GnRH agonist before controlled ovarian hyperstimulation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Course and clinical outcome of pregnancies.

RESULT(S)

Seventy-four pregnancies occurred in 73 women who received a GnRH agonist. Of these patients, 6 (8%) had a biochemical pregnancy, 6 (8%) had an ectopic pregnancy, 21 (28%) miscarried, and 41 pregnancies resulted in successfully delivered babies; there were 2 cases of congenital abnormalities.

CONCLUSION(S)

These cases, together with other published data, suggest that pregnancy outcome is not adversely affected by exposure to GnRH agonist during luteal-phase down-regulation. A central register of pregnant women who received a GnRH agonist is needed.

A comparison of three gonadotrophin-releasing hormone analogues in an in-vitro fertilization programme: a prospective randomized study

The use of gonadotrophin-releasing hormone analogues (GnRHa) has resulted in improved pregnancy rates in in-vitro fertilization (IVF) treatment cycles. Traditionally, short-acting analogues have been employed because of concerns over long-acting depot preparations causing profound suppression and luteal phase defects adversely affecting pregnancy and miscarriage rates. We randomized 60 IVF patients to receive a short-acting GnRHa, nafarelin or buserelin, or to receive a depot formulation, leuprorelin, all commenced in the early follicular phase and compared their effects on hormonal suppression and clinical outcome. We found that on day 15 of administration there was a significant difference in the suppression of oestradiol from initial concentrations, when patients on buserelin were compared with patients on nafarelin or leuprorelin (54 versus 72 and 65%; P < 0.05) and also in the number of patients satisfactorily suppressed, (80 versus 90 and 90%; P < 0.05), though there were no differences between the analogues by day 21. Similarly there was no difference in hormonal suppression during the stimulation phase or in implantation, pregnancy or miscarriage rates in comparing the three agonists. We conclude that with nafarelin and leuprorelin, stimulation with gonadotrophins may begin after 2 weeks of suppression and that long-acting GnRHa are as effective as short-acting analogues with no detrimental effects on the luteal phase.

Triptorelin acetate administration in early pregnancy: case reports and review of the literature

When using a long protocol with cycle day 23 gonadotrophin-releasing hormone agonists (GnRH-a) administration, an elevated estradiol level or a missed period 10-14 days after initiating pituitary downregulation should alert the physician to the possibility of a pregnancy. We report 4 pregnancies occurring during pituitary downregulation with Triptorelin acetate in 366 in-vitro fertilization (IVF) cycles resulting in 3 deliveries of 4 normal neonates at term and 1 first trimester abortion. This supports published data reporting a 1% spontaneous pregnancy incidence in women undergoing pituitary desensitization GnRH-a during the luteal phase prior to planned IVF treatment, a 15.9% abortion rate and a 1.7% malformation rate. Our cases together with other published data suggest that pregnancy outcome is not adversely affected by GnRH-a administration during the luteal phase of the conception cycle. However, long term follow-up of these babies is still lacking and the number of reported cases is too small adequately to rule out the possibility of any detrimental effect related GnRH-a administration in pregnancy.

Breast cancer prevention through modulation of endogenous hormones

The use of exogenous sex-steroids for hormonal contraception is important to the way of life of many modern women. The widespread use of hormonal contraceptives represents a unique opportunity to have a substantial positive impact on women's health. The observation that users of oral combination type contraceptives have a reduced risk of ovarian cancer should encourage the extension of contraceptive development to address the most important malignancy facing modern women, breast cancer. Epidemiological evidence strongly suggests that both estrogens and progestogens contribute to breast cancer risk, and account for the steep rise in risk seen during the premenopausal years. Studies of normal breast epithelial cell proliferation confirm that progestogens are breast mitogens, and explain why current contraceptives, which are progestogen dominant, do not prevent breast cancer. A long-acting depot contraceptive can be developed which releases: 1) an agonist of gonadotropin releasing hormone to suppress ovarian function; and 2) sex-steroids at doses below those in current contraceptives, and below those associated with ovulation. Such a contraceptive should provide substantial life-time protection against both breast and ovarian cancer, and would retain many of the other health benefits of current contraceptives.

Pregnancy during long-term gonadotropin-releasing hormone agonist therapy associated with clinical pseudomenopause

A case of pregnancy occurring with escape of suppression from GnRH-a therapy is described. Clinical pseudomenopause had been established, and the pregnancy was exposed to depot GnRH-a for 8 weeks. Normal pregnancy outcome demonstrated that successful implantation may occur in the first escaped ovulatory cycle.

GnRH agonists as contraceptive agents: predicted significantly reduced risk of breast cancer

Gonadotrophin-releasing hormone agonists (GnRHAs) were investigated as contraceptive agents from the late 1970's to the mid-1980's. They were abandoned as they appeared to offer no advantage over conventional combination-type oral contraceptives (COCs). This conclusion appears to be incorrect. We propose here a contraceptive regimen of a depot formulation of a GnRHA plus add-back estrogen and intermittent progestogen. The dose of add-back sex-steroids is substantially less than that in COCs; this reduction in sex-steroids should lead to a major reduction in lifetime breast cancer occurrence.

The effect of LHRH analogs on pregnancy in the baboon

Thirty-three baboons were maintained throughout their peri-ovulatory period in group enclosures with fertile males. They received treatment on days 14-19 of presumed pregnancy with either twice daily injection of 50 micrograms of an LHRH agonist or of 2 mg of an LHRH antagonist. Three pregnancies from 14 cycles were maintained in each of the treatment groups as compared to 5 of 14 in controls. Four abortions were noted but as 1 occurred in a control group the response could not be attributed to treatment. The agonist had no apparent effect on urinary progestins in nonpregnant animals but both analogs did cause a transient decline in pregnant animals. Results indicated that LHRH analogs are not suitable agents for early pregnancy termination under the present treatment regimen.

Comparisons of the potential utility of LHRH agonists and antagonists for fertility control

Prospects for the use of LHRH analogs for human fertility control have been reviewed with particular reference to two highly potent representatives. Nafarelin acetate, the LHRH agonist, has a potency about 200 X that of LHRH and is consistently effective in suppressing gonadal function in females through a desensitization of LHRH receptors in the pituitary. Such agents show promise as ovulation inhibitors for women although concern has been expressed over the dangers of unopposed estrogen or alternatively hypoestrogenemia. Although early studies indicated luteolysis in women and interceptive action in baboons it is now clear that the LHRH agonists will not be useful clinically to terminate pregnancy. Wide species differences in the male response to LHRH agonists exist. Unfortunately azoospermia has not been achieved in men. The LHRH antagonists, typified by [N-Ac-D-Nal(2)1, D-pCl-Phe2, D-Trp3, D-hArg(Et2)6, D-Ala10]LHRH, require high doses to competitively inhibit responses to endogenous LHRH. Their advantages include a rapid induction of the hypogonadal state with apparently little species or sexual variation in response. Based on animal studies, preferable utility of the antagonists would lie in male contraception and pregnancy interception.

Luteinizing hormone-releasing hormone (LHRH) and its analogs for contraception in women: a review

In animals, LHRH agonists have multiple sites of action including the pituitary, the gonads, and the reproductive tract. In humans, the major antifertility action of this class of peptides is believed to be mediated via the pituitary. Studies in women have indicated that potent LHRH agonists can block ovulation when administered once daily. In the volunteers who have used these agents no serious side effects were observed, although some women experienced irregular bleeding or amenorrhea. It is anticipated that formal clinical trials could be conducted in the near future to determine the efficacy of continuous LHRH agonist administration. Early attempts to use an LHRH agonist to produce luteal insufficiency, luteolysis, or interruption of pregnancy have either been unsuccessful or the results are still too preliminary to ascertain whether these approaches warrant further trials. LHRH antagonists are believed to act by inhibiting the action of LHRH on the pituitary. Although some of these peptides are known to be active in women, very large doses have been required. Recently several investigators have produced LHRH antagonists with increased potency. In the near future, it should be possible to determine whether these peptides should be considered as potential contraceptives in men or in women.

Clinical applications of LHRH and its analogues

The physiological requirement for activation of pituitary gonadotrophin secretion by pulsatile LHRH stimulation is discussed, and compared with the effect of pituitary stimulation by LHRH agonists. Initial stimulation is followed by a phase of progressive pituitary and gonadal inhibition. This inhibition is fully reversible at the end of agonist treatment. Clinical applications of high dose suppression are the treatment of precocious puberty and hormone-dependent tumours (mammary and prostatic carcinoma). In women, agonist administration by nasal spray is a reversible method of inhibiting ovulation, and may also be useful in the treatment of endometriosis. Clinical advantages of agonist therapy are favourable biological tolerance, lack of side effects and rapid reversibility.

Failure to induce early abortion by huge doses of a superactive LRH agonist in women

The possible abortifacient effect of the potent stimulatory luteinizing hormone-releasing hormone analogue D-Ser(TBU)6-EA10-LRH was studied in five women in early pregnancy. Four of them were treated by intravenous injections of the superactive LRH agonist in a dose of 50-125 micrograms t.i.d. for four days (total dose 600-1500 micrograms). The fifth woman discontinued treatment after the first 50 micrograms dose. The treatment was instituted on gestational day 37, 38, 40, 42 and 46. Clinical examinations and frequently taken peripheral venous blood samples for analyses of human chorionic gonadotropin and ovarian steroids were used for monitoring the treatment. No abortifacient effects of these large doses of the superactive LRH agonist were observed and the pregnancies had to be terminated by suction curettage after 10-13 days. Thus, previously described luteolytic effects by superactive LRH agonist are overcome probably by endogenous chorionic gonadotropin in early human pregnancy.

Resistance of the mouse to the antifertility effects of LHRH agonists

In the mouse, the LH-releasing activity of the LHRH agonist, D-Trp6-N alpha-MeLeu7-DesGly10-Pro9-NHEt-LHRH (Wy-40,972), was established by its ability both to induce ovulation when administered at 1600 hours on the the second day of diestrus and to elevate serum LH in adult males. While Wy-40,972 was only slightly less active in terms of these and points than it was in the rat, the predictive and possibly causal association between LH-releasing and antifertility activity established for this LHRH analog in the rat could not be clearly identified in the mouse. A total daily dose of 1000 microgram Wy-40,972/mouse was required to completely inhibit pregnancy during days 1-7 of pregnancy and produced only partial inhibition during days 7-12. This dose represents, on a body weigh basis, 8250 times the 100 percent effective pregnancy-terminating dose for the rat during equivalent intervals. The resistance of the mouse to the antifertility activity of Wy-40,972 was found not to be restricted to this particular LHRH analog or to the reproductive state. Administration of another potent LHRH analog, D-Ala6-DesGly10-Pro9-NHEt-LHRH (Wy-18,481), to adult male mice at a dose of 100 microgram/mouse/day for up to 14 days had no inhibitory effect on the weights of the testes or sex accesory organs. This dose of Wy-18,481 is 7500 times that necessary for significant reduction of these reproductive organ weights in rats within 7 days of treatment. Investigation as to the nature of the mouse's apparently divergent response to the LHRH agonists may further elucidate the antifertility mechanism of such compounds in susceptible species.