Antiprogestin drugs: research and clinical use in Sweden

The Swedish experience indicates that the combination of RU 486 and vaginal or intramuscular administration of different prostaglandin analogues such as Cervagem, Sulprostone, and 15- methyl PGF2 alpha is a highly effective and safe non-surgical method to terminate early pregnancy. The combined treatment may also be used during the second trimester. In mid- and late second trimester abortion this procedure represents a simple, non-invasive, highly effective method. There are several possibilities by which RU 486 can be used as a contraceptive. We have shown that post-ovulatory administration of RU 486 will effectively inhibit implantation. If the preliminary results are confirmed, treatment with RU 486 once a month on day LH+2 may be an attractive alternative to present contraceptive technology.

Uterine contractility and interaction between prostaglandins and antiprogestins. Clinical implications

It is generally believed that progesterone and PGF2 alpha are of major importance in the regulation of uterine contractility. The results summarized herein indicate that progesterone withdrawal is essential for the changes in uterine contractility normally observed during the secretory phase of the menstrual cycle and that the inactivity of the early pregnant uterus is progesterone dependent. Treatment with the antiprogestin RU486 will convert the inactive early pregnant uterus to an active organ and will increase the sensitivity of the myometrium to prostaglandin. These latter effects of antiprogestin have resulted in the development of highly effective, nonsurgical procedures to terminate early pregnancy based on a combined treatment with RU486 and different PG analogues administered orally, vaginally, or intramuscularly. RU486 also has a softening effect on the cervix as demonstrated in late first trimester of pregnancy. This effect may be useful as pretreatment to vacuum aspiration in late first and early second trimester abortion performed by vacuum aspiration or dilatation and curettage. In prostaglandin-induced second trimester abortions, pretreatment with RU486 will significantly reduce the induction-to-abortion interval and the dose of prostaglandin needed.

Vacuum aspiration for termination of early second trimester pregnancy after treatment with vaginal prostaglandin

Vaginal and intramuscular administration of prostaglandin analogues are routinely used for dilatation of the cervical canal prior to vacuum aspiration in first trimester abortion. Whether the same procedure is also useful during the first weeks of the second trimester has been much less investigated. In the present study, 127 women in the 13th and 14th week of pregnancy were pretreated with 3 mg 9-deoxo-16,16-dimethyl-9-methylene PGE2 administered vaginally 12 hours before surgery. At surgery the cervical canal was dilated to 9.8 mm +/- 2.5 mm (mean +/- SD) and the evacuation of the uterus was uneventful. In 21% of the patients vaginal bleeding occurred prior to the operation. The mean blood loss at surgery was 49 ml and exceeded 100 ml in only 6 patients. Gastrointestinal side effects were rare but analgesic injections were demanded by 29% of the patients during the pretreatment period. No subsequent curettage was performed during the follow-up period but 2 patients (1.6%) were readmitted because of post-abortion endometritis. It can be concluded that after pretreatment with PG, vacuum aspiration can be safely performed during the first weeks of the second trimester.

Regulation of non-pregnant human uterine contractility. Effect of antihormones

Uterine contractility was recorded on cycle day LH+6 to LH+8 in a control and treatment cycle in 14 healthy non-pregnant volunteers. In the treatment cycle the subjects received either 50 mg of the antiprogestin RU 486 daily for three days or 40 mg of the anti-estrogen tamoxifen daily for two days. The treatment started on day LH+2. During the recording, 2 to 5 micrograms PGF2 alpha was administered into the uterine cavity. The plasma levels of progesterone and estrogen were the same in both the control and treatment cycles. RU 486 caused a significant increase in uterine contractility expressed in Montevideo Units (MU) and a decrease in uterine tonus in comparison with corresponding data obtained in the control cycle. Following treatment with tamoxifen, uterine contractility was lower but the difference was not significant. PGF2 alpha invariably caused a stimulation of uterine contractility. However, treatment with the antihormones did not influence the response. The result of the present study indicates that the change in uterine contractility occurring in the latter part of the menstrual cycle and during menstruation is due to progesterone withdrawal.

Uterine contractility during pregnancy and the effect of abortifacient drugs

There are a number of compounds in clinical use for termination of pregnancy. Treatment with all of them will result in increased uterine contractility. PGF2 alpha and PGE2 as well as different prostaglandin analogues all have a direct stimulatory effect on the myometrium, while other compounds such as hypertonic saline and Rivanol seem to act mainly through a stimulation of the endogenous production of PGF2 alpha. Treatment with antiprogestins which compete with progesterone at the receptor level or which inhibit progesterone biosynthesis results in an increased uterine contractility probably through a release from progesterone inhibition. If the withdrawal of progesterone also induces an increased endogenous prostaglandin production is unclear. The medical method to induce abortion which best resembles the physiological events during a spontaneous abortion is probably treatment with antiprogestins (receptor blockers or progesterone biosynthesis inhibitors) followed by prostaglandin.

Oral administration of RU 486 and 9-methylene PGE2 for termination of early pregnancy

It has been shown that the antiprogestin RU 486 increases the sensitivity of the early pregnant human uterus to the stimulatory action of prostaglandin E analogues administered vaginally or intramuscularly. To examine if RU 486 also increases uterine sensitivity to a PGE analogue given orally, two investigative approaches were used in the present study: 1) direct registration of uterine contractions before and after administration of 9-methylene PGE2 in untreated and RU-486-treated early pregnant women; and 2) an efficacy trial involving treatment of pregnant women (amenorrhea of 49 days or less) with 25 mg RU 486 twice daily for three or four days followed by 2.5, 5.0 or 10 mg 9-methylene PGE2, or 600 mg RU486 followed by 10 mg 9-methylene PGE2 administered on day 3 and 4. The results showed that oral 9-methylene PGE2 had a clear stimulatory effect on uterine contractility which was further increased by pretreatment with RU 486. Following 2.5, 5.0 or 10.0 mg 9-methylene PGE2, the frequency of complete abortion was the same, or approximately 80%. The success rate is higher than that generally reported for RU 486 treatment alone. If 600 mg RU 486 was complemented with 10 mg 9-methylene PGE2 administered on both days 3 and 4, the frequency of complete abortion increased to 95%. Side effects were of a mild nature and generally occurred following administration of 9-methylene PGE2. The results of the present study indicate that a combined treatment based on oral administration of both the antiprogestin and the prostaglandin analogue can be developed into a highly effective and simple method to terminate early pregnancy.

The effect of RU 486 administered during the early luteal phase on bleeding pattern, hormonal parameters and endometrium

The purpose of the present study was to investigate the effect of a single dose of RU 486 administered very early in the secretory phase on endometrial development and levels of progesterone receptors, on plasma levels of gonadotrophins and ovarian hormones and on the pattern of menstrual bleeding. Twenty-four regularly menstruating subjects participated and were studied during a control, a treatment and a follow-up cycle. In the treatment cycle, a single dose of 200 mg RU 486 was given in the evening of the second day after the urinary LH peak. Plasma was collected from cycle day 10 until menstruation in both control and treatment cycles. The lengths of the control, treatment and follow-up cycles were equal. Three of the subjects had slight vaginal bleeding in association with RU 486 intake which, however, did not disturb their normal menstrual rhythm. Plasma levels of oestradiol, progesterone and FSH were not affected in the treatment cycle, whereas LH levels increased slightly. The elimination half-life of RU 486 was 28.6 h. An endometrial biopsy was taken 12, 36 or 84 h (LH + 3, LH + 4 and LH + 6) after drug intake (eight subjects in each group) and another biopsy was taken on the corresponding day in the control cycle. The specimens were assessed by morphometric analysis and for cytosolic progesterone receptor concentrations. Endometrial biopsies taken 12 h (on LH + 3) after RU 486 intake contained significantly (P less than 0.001) lower levels of cytosolic progesterone receptors than in the control cycle, but levels at 36 and 84 h were similar.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of tamoxifen on the function and lifespan of the corpus luteum and on subsequent ovarian function

The aim of the present study was to investigate the effects of tamoxifen on pituitary and luteal function and on the bleeding pattern when administered continuously in the secretory phase. The study included 16 women with regular menstrual cycles followed during one control, one treatment and one follow-up cycle. Each volunteer received 20 mg tamoxifen twice daily from cycle day 18 to menstruation in the treatment cycle. The luteal phase was slightly, but significantly prolonged during treatment, and FSH, progesterone, 17-hydroxyprogesterone, 20 alpha- dihydro progesterone, estrone, estrone sulphate and estradiol significantly elevated in comparison with corresponding data during the control cycle. The results indicate that estrogen may be of some importance for the regulation of the life span of the corpus luteum in the human. The significantly elevated levels of pregnanediol glucuronide and estrone glucuronide during the follow-up cycle are most likely a result of either a direct effect of remaining circulating tamoxifen levels on the ovary, or mediated through the increased release of FSH. If estrogens are of importance for the process of implantation, which has recently been suggested in sub-human primates, also in the human remains unclear. Studies on the effect of anti-estrogens on the endometrium during the secretory phase of the cycle are ongoing.

Termination of early human pregnancy with RU 486 (mifepristone) and the prostaglandin analogue sulprostone: a multi-centre, randomized comparison between two treatment regimens

A multi-centre, randomized trial was conducted to compare the efficacy and side-effects of two combination regimens of the antiprogestin RU 486 and the intramuscular PGE2 analogue sulprostone for termination of early pregnancy (amenorrhoea up to 49 days). Women in the 3-day group (n = 125) received 25 mg RU 486 twice daily for 3 days plus a single injection of 0.25 mg sulprostone in the morning of the third day of antiprogestin treatment. In the 4-day group (n = 126), RU 486 was given for 4 days and the sulprostone injection in the morning of the fourth day. Treatment outcome in the two groups was similar. Overall, 88.8% had a complete abortion, 6.8% an incomplete abortion and 2.4% were treatment failures; in the remaining 2% treatment outcome could not be determined. Only three of the six women with treatment failure still had detectable fetal heart activity when the pregnancy was terminated by vacuum aspiration two weeks after the start of treatment. Five of the 17 interventions for incomplete abortion were carried out as emergency procedures because of heavy bleeding; two of these five women were given a blood transfusion. The majority of the curettages (10/17) were performed in one centre. If the data from this centre and the women with undetermined treatment outcome were excluded, the rates for complete abortion, incomplete abortion and treatment failure in the remaining six centres were 93.6, 3.7 and 2.7%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of oral prostaglandin E2 on uterine contractility and outcome of treatment in women receiving RU 486 (mifepristone) for termination of early pregnancy

It has been shown that the antiprogestin RU 486 (mifepristone) increases the sensitivity of the early pregnant human uterus to the stimulatory action of synthetic prostaglandin E (PGE) analogues. To examine if RU 486 also increases uterine sensitivity to the naturally occurring PGE2 given orally, two investigative approaches were used in the present studies: (i) direct registration of uterine contractions before and after PGE2 administration in untreated and RU 486-treated early pregnant women; and (ii) a double-blind, randomized, controlled efficacy trial involving treatment of pregnant women (amenorrhoea of less than or equal to 49 days) with RU 486 (25 mg twice daily for 4 days) and PGE2 (1 mg once or twice) or placebo on the last day of RU 486 treatment. The results indicate that oral PGE2 at the doses employed had little or no stimulatory effect on uterine contractility and that it did not improve the rate of complete abortion achieved with RU 486 alone. Overall, 25 of 42 women (59%) had a complete abortion, 15 women (36%) did not abort and the remaining two had incomplete abortions. Women with complete abortions had significantly lower pretreatment levels of progesterone and a longer duration of induced bleeding than those who did not abort. Thus oral PGE2, when given in clinically acceptable doses, is not a suitable alternative to synthetic PGE analogues for use in combination with RU 486 for termination of early pregnancy.

Vascular changes in the human endometrium following the administration of the progesterone antagonist RU 486

Eleven healthy women were assigned to one of two groups. They received 50 mg RU 486 orally per day either on cycle days 7 to 10 (preovulatory group n = 5) or on cycle days 20 to 23 (postovulatory group, n = 6). An endometrial biopsy was taken on the fourth day of the RU-treatment in the preovulatory group and on the second (n = 2) or fourth (n = 4) treatment day in the postovulatory group. Biopsies from 34 untreated women representing matched samples from early and mid preovulatory phase (n = 10) and mid and late postovulatory phase (n = 24) were used as control. The ultrastructure of the endometrial capillaries was investigated by morphometric methods. The administration of RU 486 during the preovulatory phase did not modify the vascular structure. However, when given in the postovulatory phase, necrosis occurred in the capillary endothelial cells with and without regressive changes of the adjacent stroma. The area and diameter of the capillary lumen and the area of the adventitia was smaller than in the control material (p less than 0.01). The result of the study suggests that RU 486, when administered in the postovulatory phase, directly affects the capillary vessels of the endometrium.

Termination of early pregnancy with RU 486 (mifepristone) in combination with a prostaglandin analogue (sulprostone)

The antiprogestin RU 486 (mifepristone) has been shown to induce abortion when administered in early pregnancy, but the rate of incomplete abortion is high, around 40%. As blockage of the progesterone receptor increases the myometrial sensitivity to prostaglandins, a combination of RU 486 and a prostaglandin E2-analogue was tested for termination of pregnancy. One hundred and sixteen women, with a gestational length of less than 49 days from the first day of the last menstrual period, were treated with a daily dose of 50 or 100 mg RU 486 for 3 to 6 days, complemented with an intramuscular dose of 0.25 mg sulprostone (16-phenoxy-PGE2-sulfonylamide) on the last day of RU 486 treatment. The results confirmed that a reduction of treatment duration to 3 days is just as effective for inducing abortion (91% complete abortion) as a 4-6-day treatment regimen (95% complete abortion). Six patients had an incomplete abortion and in one the pregnancy continued unaffected. Side effects included intense uterine pain after the prostaglandin administration (16%), vomiting associated with the antiprogestin intake (9%) and after the prostaglandin administration (9%). One woman needed emergency curettage due to heavy bleeding. Six percent of the treated patients had a decrease in hemoglobin exceeding 20 g/l during the first week but no patient needed blood transfusion. No serious side effects were recorded.

Prostaglandins and antiprogestins

There is considerable interest in the development of a non-surgical method to terminate early pregnancy. During the three weeks immediately following the first missed menstrual period, several prostaglandin (PG) analogs such as sulprostone, gemeprost and 9-methylene PGE2 have been used to terminate the pregnancy. Prostaglandins, however, at the doses required to induce disruption of the conceptus cause gastrointestinal side effects and uterine pain which are more severe than those subsequent to vacuum aspiration. Treatment with the antiprogestin, mifepristone counteracts the effects of progesterone in pregnancy and thus prevents maintenance of the pregnancy. Mifepristone administered alone causes termination of the pregnancy in most, but not all, cases. In addition to removing the influence of progesterone, mifepristrone also induces regular uterine contractions and significantly increased the sensitivity of the uterus to PG analogs. Mifepristone (50 mg/day) followed by an intramuscular injection of a low dose, (0.25 mg), of sulprostone (approximately 1/6 of the dose of prostaglandin necessary to induce abortion if used alone) was highly effective in terminating early pregnancy, causing complete abortion in 94% of cases. Gastrointestinal side effects were rare and uterine pain significantly less common than if PG analogs were used alone. Subsequently the combination of mifepristone and vaginal administration of gemeprost (0.5-1.0 mg) has been shown to be equally effective Ideally, the PG analog would be administered orally rather than by injection or vaginal administration. Preliminary data indicate that 9-methylene PGE2 but not PEG2 may be suitable for this purpose in combination with mifepristone.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of RU486 administered during the proliferative and secretory phase of the cycle on the bleeding pattern, hormonal parameters and the endometrium

Seventeen healthy women aged 24-45 years with regular menstrual periods, proven fertility and not using steroidal contraceptives or IUD were recruited for the study. The volunteers were followed during one control, one treatment and one follow-up cycle. Daily morning urine samples were obtained during the control and the treatment cycle. The samples were analysed with regard to pregnanediol glucuronide (P2-G), oestrone glucuronide (E1-G), oestradiol (E2), progesterone (P4), LH and creatinine. During the entire 3-month study the subjects kept a record of uterine bleeding and side effects. The subjects received 50 mg RU486 daily either on cycle days 7-10 (n = 7) or on cycle days 20-23 (n = 10). An endometrial biopsy was taken on cycle day 10 in the first group and on cycle days 21-28 in the second group of patients. Treatment during the proliferative phase caused significant prolongation of the cycle length due to a delay of the oestrogen and LH surge. However, once the oestrogen concentration started to increase, the remaining part of the cycle was normal. The length of the follow-up cycle was similar to that of the control cycle. The morphology of the endometrium did not differ from control samples taken from untreated women at the same time of the cycle. All ovulating women (n = 9) treated in the mid-luteal phase started to bleed on the 3rd to 4th day of the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of a vaginal gel containing 9-deoxo-16,16-dimethyl-9-methylene PGE2 for cervical dilatation and pregnancy termination

A stable hydrophilic gel for vaginal administration containing 9-deoxo-16,16-dimethyl-9-methylene PGE2 (9-methylene PGE2) was developed and its clinical usefulness for preoperative cervical dilatation and for termination of first and second trimester pregnancy evaluated in 521 pregnant patients admitted to the hospital for therapeutic abortion. Following vaginal administration of 3 mg of 9-methylene PGE2 gel a peak plasma level of between 3.5 and 10 ng/ml was found 3 to 6 hours following treatment. The "bioavailability" of the drug was in the order of 25-30%. 9-methylene PGE2 was found to be equally effective as 1 mg Cervagem for preoperative cervical dilatation. With a pretreatment period of 3 hours side effects were rare with both compounds. If the pretreatment period was extended to 12 hours the degree of cervical dilatation, but also the frequency of side effects increased significantly. Repeated administration of 9-methylene PGE2 was found to be effective (96% complete abortion) in terminating very early pregnancy provided the total dose was 10 mg or more. During second trimester the minimum effective dose was 4.5 mg of the compound repeated every fourth hour. The results of the present study have shown that with the new gel formulation the amount of 9-methylene PGE2 needed to terminate first and second trimester pregnancy was approximately ten times less in comparison with the previously used lipid base suppositories. The treatment was also associated with a low frequency of side effects.

The effect of the antiprogestin RU 486 on uterine contractility and sensitivity to prostaglandin and oxytocin

The effect of RU 486, a steroid acting as an antiprogestin at the receptor level, on uterine contractility and sensitivity to the prostaglandin analogue, 16-phenoxy-PGE2 methyl sulfonylamide (16-phenoxy-PGE2) and to oxytocin was studied in 29 women in early pregnancy. Seven untreated women at the same stage of pregnancy served as controls. In the untreated women no spontaneous uterine contractility was recorded and the response to 0.25 mg 16-phenoxy-PGE2 was characterized by an increase in uterine tonus with superimposed irregular contractions of low amplitude. Treatment with 25 mg RU 486 twice daily resulted in the appearance of regular uterine contractions at 24 h in two out of five patients and in all patients at 36, 48 and 72 h after the start of RU 486 treatment. The withdrawal of progesterone influence changed the inactive early pregnant uterus into an active organ. Administration of 16-phenoxy-PGE2 caused an obvious stimulation of both frequency and amplitude of the contractions. In addition, the significantly increased sensitivity to the prostaglandin analogue, but not to oxytocin, was already apparent 24 h after the start of RU 486 treatment. We have previously shown that the addition of one intramuscular injection of 16-phenoxy-PGE2 on the fourth day of treatment with RU 486 (25 mg twice daily) significantly increased the abortifacient effect of the antiprogestin during early pregnancy. The present study suggests that a shorter treatment may be possible.

Plasma levels of antiprogestin RU 486 following oral administration to non-pregnant and early pregnant women

RU 486 is a synthetic steroid which acts as an antiprogestin at the receptor level. The clinical usefulness of the compound for menstrual regulation and termination of early pregnancy is currently being evaluated. The aim of the present study was to determine the plasma levels of RU 486 following the oral administration of the compound to 42 pregnant and 10 non-pregnant women. The levels of RU 486 were measured by a radioimmunoassay method which uses chromatography on Sephadex LH 20 columns. The identity of the compound assayed as RU 486 was confirmed, but the presence of small amounts of two highly cross-reacting metabolites (monodemethyl and didemethyl RU 486) in the analyzed fractions could not be excluded. Following the ingestion of a single tablet containing 25 and 50 mg of the compound, a peak plasma value of approximately 3.5 to 4.0 mumol/l in both the pregnant and non-pregnant subjects was reached one to two hours later. The half-lives of elimination were about 20 hours in both the pregnant and the non-pregnant women. Following the repeated oral administration of 50, 100 or 200 mg of RU 486 daily for four days, maximum plasma levels of 2.9, 4.5 and 5.4 mumol/l, respectively, were found. Thus, the increase in plasma levels was not directly proportional to the increase in the dose. No accumulation of RU 486 in the plasma was found, even when the duration of treatment was prolonged to six days. The data partly explain the reported lack of relation between ingested dose and frequency of induced abortion and they may be useful for designing future studies on the use of compound to prevent implantation, induce menstruation or terminate an early pregnancy.

Progesterone receptor blockage. Effect on uterine contractility and early pregnancy

RU 486 is an antiprogestin which acts at the receptor level. In the present study the effect of this compound on uterine contractility and sensitivity during early pregnancy was evaluated in 10 patients. Five patients in the 6th to 7th week of pregnancy received 25 mg RU 486 twice daily for four days. On the fourth day of treatment, uterine contractility was recorded. The remaining five early pregnant patients were untreated and served as control. Withdrawal of progesterone locally by RU 486 treatment resulted in the development of a regular uterine activity which was in sharp contrast to the low level contractility pattern found in the untreated control patients. Also the sensitivity to prostaglandin increased following RU 486 treatment. The efficacy of a sequential therapy of RU 486 and the PGE analogue 16-phenoxy-tetranor-PGE2 methyl sulfonylamide for termination of early pregnancy was also studied. Thirty-four early pregnant women (duration of amenorrhea for up to 49 days) admitted to the hospital for termination of their pregnancy volunteered for the study. The patients received 25 mg RU 486 twice or four times daily for four days. In the morning of the fourth day of RU 486 treatment, a small dose (0.25 mg) of the PGE analogue was given as a single intramuscular injection. The combined treatment resulted in complete abortion in 32 patients (94%). One patient experienced an incomplete abortion and in one patient the pregnancy continued unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Termination of very early pregnancy by RU 486--an antiprogestational compound

RU 486, a new antiprogestational compound, was given to 37 women seeking termination of pregnancy and with amenorrhea of 42 days or less. One patient was found at the second follow-up visit to have an extrauterine pregnancy. The patients received either 25 mg, 50 mg or 100 mg RU 486 twice daily for four days. All patients attended three follow-up visits, one, two and five to six weeks after the start of therapy. The start, duration and amount of bleeding as well as plasma progesterone, beta-hCG and cortisol concentrations were determined for each treatment day and at the follow-up visits. All patients but three started to bleed during treatment. Frequency of complete abortion was 61% (22 out of 36 patients). In only three patients was the pregnancy unaffected by treatment. The clinical efficacy of the treatment was not dose-dependent. Most of the patients experienced only minor side effects in terms of mild uterine pain, nausea and vomiting. However, two patients suffered from heavy bleeding requiring blood transfusion and curettage. In the patients with complete abortion, beta-hCG values decreased significantly but not until the first follow-up visit. The plasma progesterone also decreased. The decrease appeared earlier with the higher daily dose of RU 486. Cortisol concentrations increased during treatment with all 3 dosage regimens but the levels remained within the normal range. It is concluded that treatment with RU 486 may provide a novel therapy for "menstrual regulation" but the efficacy of the treatment needs to be improved to compete with alternatives such as vacuum aspiration.

Diurnal variation of uterine contractility

The diurnal uterine activity in four normal women in the secretory phase of their menstrual cycles and one woman suffering from dysmenorrhea were studied in relation to concomitant hormone levels in blood (progesterone, hGH, prolactin, cortisol, vasopressin, and 15-keto-13,14-dihydro-PGF2 alpha). In the four normal women uterine activity decreased after midnight, unrelated to circulating levels of 15-keto-13,14-dihydro-PGF2 alpha. But during a dysmenorrheic episode the uterine hypercontractility pattern correlated well with levels of the PGF2 alpha-metabolite, indicating a role of endogenous-produced PGF2 alpha in this condition. The results demonstrate a diurnal rhythm, possibly related to the wake-sleep cycle. No simple associations were seen between vasopressin, cortisol, prolactin, hGH, the PGF2 alpha-metabolite, and uterine activity.

The possible roles of prostaglandins and related compounds in endometrial bleeding. A mini-review

This mini-review summarizes some aspects of hemostatic defects, with particular reference to endometrial bleeding, both the normal menstruation and some bleeding disorders of the uterus. Two cell types are of particularly great interest in the hemostatic mechanism, viz. the platelet and the vascular endothelial cell. We will therefore start with a brief survey of the roles of platelets and vascular endothelium in hemostasis, and the underlying biochemical events will be discussed, particularly the participation of the arachidonate metabolites: the prostaglandins, the thromboxanes and the leukotrienes. This section is then followed by a brief description of some histological findings in the menstruating endometrium; the normal as well as the pathologically bleeding tissue. The possible roles of arachidonate metabolites in these events will be discussed. Several clinical studies have been published, in which various attempts have been made to treat excessive endometrial bleeding with inhibitors of prostaglandin biosynthesis. The findings in these studies are described. The relevance of this approach and its possible effects on other areas of arachidonic acid metabolism will be discussed. Finally, some studies will be summarized in which various attempts have been made to quantitate and endometrial prostaglandins in different physiological and pathological conditions.

The effect of intravenous and intrauterine administration of prostacyclin on non-pregnant uterine contractility in vivo

Intravenous administration of prostacyclin at a dose of 10 ng/min/kg bodyweight for 10 minutes did not have any effect on non-pregnant human contractility in three subjects. Higher doses were not given due to side effects. Intrauterine administration of PGI2 at doses of 0.3-0.6 micrograms resulted in a gradual stimulation of the myometrial activity. Whether this response is a secondary effect of the vasodilation caused by PGI2 or a direct effect on the myometrium could not be established in these experiments.