The current status of prostaglandins as abortifacients

Bacterial lipopolysaccharide-mediated fetal death. Production of a newly recognized form of inducible cyclooxygenase (COX-2) in murine decidua in response to lipopolysaccharide

Maternal infection is a cause of spontaneous abortion and preterm labor in humans, but the pathophysiology is unclear. We hypothesized that eicosanoids play an important role in infection-driven pregnancy loss. To investigate this hypothesis, we administered lipopolysaccharide (LPS) to pregnant C3H/HeN mice and found that LPS administration caused fetal death in a dose-dependent fashion. Pretreatment with indomethacin significantly decreased the proportion of fetal death from 83% to < 25% in mice injected with 10 micrograms of LPS. Also, decidual explants from LPS-treated mice produced significantly more inflammatory eicosanoids, including prostaglandins E2 and F2 alpha and thromboxane B2, than controls. We investigated the regulatory mechanisms responsible for increased decidual prostanoid production in response to LPS. Western and Northern blots demonstrated that decidual protein and mRNA levels of a recently recognized highly inducible form of cyclooxygenase, COX-2, were substantially increased in mice treated with LPS. Induction of COX-2 was rapid: mRNA was detected 30 min after LPS injection. In contrast, another form of cyclooxygenase, COX-1, was only minimally induced in response to LPS. Our data indicate that LPS induces decidual prostanoid production via increased COX-2 expression. Since LPS-mediated fetal death is markedly diminished by pretreatment with indomethacin, COX-2-mediated eicosanoid production is likely a key pathophysiologic event in LPS-mediated fetal death.

Premedication and pain relief with Nubain during second trimester therapeutic pregnancy terminations

OBJECTIVE

To determine the analgesic efficacy of the opioid agonist-antagonist Nubain during midtrimester therapeutic terminations with intra-amniotic PGF2 alpha or i.m. administration of the PGE2 derivative sulprostone.

METHOD

Following osmotic predilatation with laminaria tents patients were given as a premedication 10 mg Valium, 10 mg Nubain and 0.5 mg atropine i.m. prior to prostaglandin treatment, and sequential doses of Nubain during the uterine contractility period. Patients indicated their own perception of uterine pain on a differential graphic rating scale, and the attending physician also evaluated patients' discomfort on a 5-grade scale.

RESULT

In 55% of the cases patients experienced only 'mild' or 'moderate' pain. The mean induction-to-abortion interval was short (11.6 +/- 1.3 h). The well known gastrointestinal side-effects of the prostaglandins were avoided.

CONCLUSION

Nubain proved effective in stabilizing patients' condition during intra-amniotic instillation of prostaglandin, effectively relieved uterine pain during the myometrial contractility period, prevented the occurrence of prostaglandin-related side-effects, and provided simple and good anesthesia during instrumental removal of the already detached but retained placenta.

Intrauterine administration of drugs for termination of pregnancy in the second trimester

Medical methods have been used for many years to terminate mid-trimester pregnancy, ranging from irritant chemicals and traditional plants to ecbolic agents and solutions instilled locally into the uterus. These methods had serious limitations, with relatively high rates of maternal mortality and morbidity. Surgical evacuation requires special skills not available to all practitioners and many doctors consider second trimester dilatation and evacuation as a surgical taboo. In recent years several approaches evolved and reached the clinics, presenting safer and more effective options. Intra-amniotic instillation of hypertonic solutions, particularly saline or urea, proved in many hands to be a good method for pregnancies beyond 15 weeks of gestation. Due to a long latency period after instillation, these agents are often supplemented by an intravenous oxytocin infusion. Extraovular hypertonic saline or ethacridine (Rivanol) have their advocates, particularly in the grey-zone of pregnancy range from 13-15 weeks. In the last two decades, intrauterine prostaglandins were added to the methods in current use. Extra-amniotic prostaglandins (E2, F2 alpha or 15-methyl F2 alpha) were originally given in repeated doses or as a continuous local drip, but later a single instillation was used, usually mixing the drug with a viscous solution or gel. Intra-amniotic prostaglandins, in much higher doses, particularly the 15-methyl analogue, proved highly effective and relatively safe, especially when combined with laminaria tent insertion in the cervix. Various combinations of methods have provided a wide spectrum of data which is difficult to evaluate at present. Studies comparing different methods were mainly attempted in the mid-seventies. The outcome raised many pertinent questions and left many major issues unresolved. Most of the comparisons were not randomized or well-controlled and only referred to the natural prostaglandin compounds. The analogues, however, seem to offer several advantages and the role of additional methods such as laminaria or antiprogestins remains to be further evaluated.

Prostaglandin E and F2 alpha receptors in human myometrium during the menstrual cycle and in pregnancy and labor

The binding of prostaglandins E1 and F2 alpha has been studied in the human myometrium and cervix during the menstrual cycle and in the myometrium of pregnant patients at term before and during labor. Tritium-labeled prostaglandin E1 and F2 alpha binding was saturable and reversible. Scatchard analysis of tritium-labeled prostaglandin E1 binding was linear, which suggests a single class of high-affinity binding sites with an estimated apparent equilibrium dissociation constant of 2.5 to 5.4 nmol/L and inhibitor affinities of 0.9, 273, 273, and 217 nmol/L for prostaglandins E2, A1, B1, and F2 alpha, respectively. Scatchard analysis of tritium-labeled prostaglandin F2 alpha, binding was also linear, but the affinity of these binding sites was much lower, with an average dissociation constant of 50 nmol/L and inhibitor affinities of 1.6, 2.2, and 11.2 nmol/L for prostaglandins E1, E2, and A1, respectively. In nonpregnant patients, the concentrations and affinities of tritium-labeled prostaglandin E1 binding sites were similar in the myometrium during the proliferative and secretory phases of the menstrual cycle, but the concentration of these sites was much lower in the cervix. The concentration of the tritium-labeled prostaglandin E1 binding sites was significantly lower in the myometrium of pregnant patients at term than in the myometrium of nonpregnant patients. The concentrations and affinities of tritium-labeled prostaglandin E1 binding sites were not significantly different in the upper and lower myometrium of pregnant patients at term or in the myometrium of such patients before and during labor. The concentrations of the tritium-labeled prostaglandin F2 alpha binding sites during the menstrual cycle and in pregnancy at term were similar to those of tritium-labeled prostaglandin E1 binding sites. In addition to confirming the presence of specific prostaglandin E and F2 alpha binding sites in the myometrium, these data also suggest: that specific prostaglandin E binding sites are present in the cervix and that the concentrations and affinities of prostaglandin E binding sites do not change during the menstrual cycle and are similar before and during labor in pregnant patients at term.

Ovum transport in the rhesus monkey following postovulatory intravaginal 15(S)-15-methyl prostaglandin F2 alpha-methyl ester administration

The effects of postovulatory intravaginal 15(S)-15-methyl prostaglandin F2 alpha-methyl ester (Me PGF2 alpha) on ovum transport was assessed in the spontaneously ovulatory rhesus monkey. A single suppository containing 3.0 mg of Me PGF2 alpha in lipid base was inserted intravaginally in adult female monkeys 14 to 36 hours following laparoscopically timed ovulation. The reproductive tract was flushed 2, 4, or 24 hours later to recover ova. Four of five ova were recovered at 2 hours, one of five at 4 hours, and none of five at 24 hours after insertion. All ova recovered were in the oviduct. Since ova are normally found in the oviduct until 72 hours after ovulation, these results are interpreted to indicate acceleration and expulsion of ova from the tract following exposure to intravaginal Me PGF2 alpha in excess of 4 hours.

Termination of pregnancy complicated by anencephaly with intra-amniotic prostaglandin F2 alpha

It is anticipated that there will be more frequent need to terminate anencephalic pregnancies of greater than 20 weeks' duration before term. Since present methods are unsatisfactory, the use of incremental intra-amniotic injections of prostaglandin F2 alpha with continuous monitoring of intrauterine pressure was evaluated in three cases. The method appears to be satisfactory.

Plasma levels of 15 (S) 15-methyl-PGF 2 alpha-methyl ester following vaginal administration for induction of abortion in women

A single suppository containing 3.0 mg 15 (S)15-methyl-PGF2 alpha-methyl ester was administered vaginally in women to terminate mid-trimester pregnancy. Plasma levels of the drug (both methyl ester and free acid forms) were measured at different time intervals using deuterated carriers and gas chromatography-mass-spectrometry. 15(S)15-methyl PGF2 alpha (sum of methyl ester + free acid) was found to have a mean value of 1166 pg/ml plasma at 3 hrs after administration of the suppository. The mean levels were subsequently found to be maintained in the range of 1000 pg/ml. Preliminary studies showed that unlike the successfully aborted women, in those who did not abort within 30 hrs with this suppository, the plasma levels of the drug were not maintained for a sufficiently long time. The episodes of side effects, body surface area and the induction-abortion interval in relation to the plasma levels are discussed.

Efficacy and acceptability of intravenously administered sulprostone, a tissue-selective prostaglandin-E2 derivative, for induction of first-trimester abortion

The abortifacient effect of a new tissue-selective prostaglandin E2-derivative, sulprostone, administered intravenously, has been investigated in 166 women in the the first trimester of pregnancy. Four different dose schedules (1.7 mcg/min for 5 or 10 hour--total dose 500 mcg or 1000 mcg, 2.8 mcg/min and 4.1 mcg/min for 6 hours--total dose 1000 mcg and 1500 mcg) have been evaluated. No absolute failures occurred and no severe complications or side-effects were recorded. Best results (high abortifacient efficacy and low systemic side-effects) were obtained by infusing 1000 mcg sulprostone in appr. 10 h. Our study indicates that sulprostone appears to have a high degree of acceptability.

Midtrimester abortion with prostaglandin and hypertonic saline--a comparative study

This study was conducted in Baroda, India, to evaluate and compare the safety and effectiveness of intraamniotic prostaglandin F2alpha (PGF2alpha) and 20% saline augmented with intravenous oxytocin for terminating 200 pregnancies of 14 to 20 weeks' gestation. While there was no method failure among the group treated with saline, ten method failures were reported for patients treated with the PGF2alpha. The rate of incomplete abortions was significantly lower for the group treated with saline (19.4%) than it was for the group treated with the PGF2alpha (33.7%). The administration of oxytocin after fetal expulsion did not reduce the rate of incomplete abortion. The mean instillation-to-abortion time was significantly lower with saline than with PGF2alpha. The incidence of gastrointestinal side effects and excessive bleeding (less than 200 ml) during the procedure was significantly higher for patients treated with PGF2alpha than for those treated with saline.

Catecholamines during therapeutic abortion induced with intra-amniotic prostaglandin F2alpha

Serial plasma, amniotic fluid, and urine samples were analyzed for epinephrine (E) and norepinephrine (NE) in eight subjects during midtrimester abortion induced by intra-amniotic prostaglandin F2alpha (PGF2alpha). After PGF2alpha administration, plasma E increased and there was no change in plasma NE levels. Amniotic fluid levels of E and NE decreased initially. During the course of abortion the mean level of E in the amniotic fluid increased after fetal distress and decreased after fetal death, indicating that the midtrimester fetus of both E and NE increased following PGF2alpha. The observation that mean plasma levels and urinary excretion rate changes correlated better with the course of abortion and uterine contractility rather than with the time of PGF2alpha administration was consistent with the hypothesis that the catecholamine response may be due to the stress of labor rather than to the PGF2alpha per se.

Induction of abortion by intrauterine administration of prostaglandin via laparoscopy with concurrent sterilization

This is a preliminary report of a method of inducing abortion at 12 to 15 weeks' gestation, a period when none ot the currently available methods are wholly satisfactory. The authors investigated both prostaglandin F2ALpha (PGF2alpha) and 15-methyl PGF2alpha injected intramyometrially and intraamniotically under laparoscopic visualization prior to sterlization as a means of inducing abortion. They conclude that the results from this small series (13 patients) indicate that this is a practicable method for abortion combined with sterilization for patients at 10 to 15 weeks' gestation and recommend that further comparative studies be undertaken.

Second trimester abortion: single dose intra-amniotic injection of prostaglandin F2alpha with intravenous oxytocin augmentation

One hundred-sixty mid-trimester pregnancies were terminated by intra-amniotic injection of Prostaglandin F2alpha with concomitant intravenous oxytocin. Only four of 77 nulliparas and one of 83 multiparas required a second prostaglandin injection. Mean injection-abortion interval was 22.8 hours, and 17.0 hours respectively. This difference between groups was statistically significant. Four nulliparas sustained uterine trauma, a high incidence suggesting that this method may be ill-advised in these women. Because of the predictable short injection-abortion interval in the multipara, this method can be combined conveniently with surgical sterilization.

The effect of prostaglandin f2alpha on endocrine parameters in early pregnancy

The luteolytic effect of prostaglandin f2alpha (PGF2alpha) has been well documented in a variety of primates. This property has not been proven in early human pregnancy. A study of the luteolytic activity of extraamnial administration of 5 mg PGF2alpha was carried out on 7 healthy women who were less than 6 weeks pregnant and on 4 women who were more than 9 weeks pregnant. Serum levels of 17beta-estradiol, 17-hydroxyprogesterone, progesterone and human chorionic gonadotropin (HCG) were measured by radioimmunoassay before, during and after the administration of PGF2alpha. Abortion was successfully induced in all the patients with early pregnancies, but in the control group of more mature pregnancies only one of the four women aborted. In the older pregnancies, the administration of 5 mg PGF2alpha caused no significant alteration in the serum levels of the measured hormones. In the younger pregnancies the serum concentration of 17beta-estradiol and progesterone decreased within hours after PGF2alpha administration. Serum 17-hydroxyprogesterone concentrations remained unchanged at a high level and declined significantly later in a manner similar to HCG. This discrepancy in the decline of 17-hydroxyprogesterone as opposed to progesterone and 17beta-estradiol may be explained by two mechanisms, the one mechanical, and the other secondary luteolytic. The marked increase of intrauterine pressure occurring within minutes after PGF2alpha instillation damages the fetoplacental unit. This leads to a decrease in the placental steroido-genesis and HCG production necessary for the maintenance of the corpus luteum.

Abortion deaths associated with the use of prostaglandin F2alpha

Six abortion-related deaths associated with the use of prostaglandin F2alpha were reported through the Center for Disease Control's surveillance of abortion deaths between 1972 and 1975. Prostaglandin may have had only indirect association with these deaths. The patients' ages ranged from 16 to 38 years, their length of gestation ranged from 15 to 24 menstrual weeks, four were white, and three were nulliparous. Four patients had pre-existing conditions that increased their risks and contributed to their death. The estimated death-to-case rate for prostaglandin F2alpha was 10.5 per 100,000 abortions. Although lower than the rate for intra-amniotic saline instillation, this death-to-case rate is only an approximation. The relative safety of intra-amniotic prostaglandin F2alpha as a second-trimester abortifacient, compared to saline, remains to be established.

Induction of abortion with 15(S)-15-methyl PGF2alpha (Tham) vaginal suppositories

The repeated administration of vaginal suppositories containing 1 mg 15(S)-15 methyl PGF2alpha (Tham) sucessfully induced abortions in 60 of 62 patients. Among patients who successfully aborted, the mean abortion time was 19.0 hours. The mean abortion time was not related to gestational age or parity. Sixty (96.8 precent) aborted within 48 hours, and 53 (85.5 percent) aborted within 24 hours. Gastrointestinal side effects occurred for 33.9 percent of the patients. Diarrhea was the most frequent side effect. The abortion was complete for 40.3 percent of the patients.

Induction of midtrimester abortion by the combined method of continuous extravovular infusion of prostaglandin F2alpha and intracervical laminaria tents

Midtrimester abortion was successfully induced in 55 of 60 patients with continuous extraovular infusion of prostaglandin F2alpha (PGF2alpha) following the insertion of intracervical laminaria tents. Intravenous oxytocin was also used in 38 (63%) of the 60 patients. The mean induction-abortion time (IAT) was 11.72 hours +/- 1.06 SD). Abortion was completed in 40% within 8 hours, 80% within 16 hours, and 93% within 24 hours. The mean total dose of PGF2alpha was 41.9 mg. There was no significant difference in IAT between the parous patients (13.40 hours +/- 1.90 SD) and the nulliparous patients (10.41 hours +/- 1.13 SD). There was no apparent correlation between IAT and the stages of gestation (12 to 22 weeks). The five patients who failed to abort within 24 to 36 hours underwent uterine evacuation, which was easily accomplished because there was a marked degree of cervical dilatation. Side effects and complications of the technique were few. Endometritis occurred in three patients, two of whom had had intrauterine devices in situ until just prior to the procedure. It appears that this method has a high success rate, an acceptable safety factor, good patient tolerance, and relatively few side effects.

Abortifacient efficiency of 15 (S) 15-methyl-prostaglandin F2alpha-methyl ester administered vaginally during early pregnancy

Forty early pregnancies (menses delay 13 - 27 days) were terminated by administering four vaginal suppositoreis each containing 1.0 or 1.5 mg of 15 (S) 15-methyl-prostaglandin F2alpha-methyl ester, one every third hour. In 14 cases serial measurementsof serum estradiol and progesterone were performed during and after therapy. Uterine contractions and bleeding started 1 - 17 hours after administration of the first suppository. Abortion was complete after one week in five women (13%), and after two weeks in 30 (75%). A curettage was performed on eight women, residual placental fragments were found in seven and pregnancy continued in one woman. Mild diarrhoea (65%) and vomiting (40%) were the major side-effects, despite premedication. Estradiol and progesterone levels fell progressively during the therapy. Self-administration of 4 or 6 mg of the methyl ester caused too low a rate of complete abortion for use in practice, but it may be a valuable and practical agent for preoperative dilation of the cervix.

Midtrimester abortion: a comparison of intraamniotic prostaglandin F2alpha and hypertonic saline

The safety and effectiveness of two intraamniotic prostaglandin F2alpha (PGF2alpha) dose schedules (a single 50 mg dose and a repeated 25 mg dose) and intraamniotic hypertonic saline were evaluated in a study where each abortion procedure was randomly assigned to 50 patients. All patients were at 16 to 20 weeks' gestation. Rates of gastrointestinal and other side effects were generally higher for the 50 mg PGF2alpha dose schedule than for the other two procedures. The repeated 25 mg PGF2alpha dose schedule resulted in higher 24-hour (68.0%) and 48-hour (98.0%) cumulative abortion rates than the 50 mg PGF2alpha dose schedule (54.0%, 92.0%) or saline (34.7%, 91.8%). Rates of spontaneous placental expulsion were highest for the repeated 25 mg PGF2alpha dose (74.0%) and lowest for the 50 mg PGF2alpha dose schedule (40.0%).

Repeated extra-amniotic administration of prostaglandin F2alpha for midtrimester abortion

Midtrimester abortion was induced in 94 of 100 patients at 16 to 24 weeks' gestation by the extra-amniotic administration of 1170 microng of prostaglandin F2alpha (PGF2alpha) every 10 minutes. The number of prostaglandin doses varied from 16 to 24 depending on the patient's response to the prostaglandin. The median abortion time was 10.0 hours, and 82.0% of the patients aborted within 24 hours. Overall, 68.0% of the patients failed to expel the placenta within one hour of abortion of the fetus. Vomiting and diarrhea occurred among 42.0 and 17.0% of the patients, respectively. Compared with the intra-amniotic administration of a single 50 mg dose of PGF2alpha, the extra-amniotic procedure was associated with similar side effect rates, a higher rate of incomplete abortion, and a significantly shorter abortion time.

Midtrimester prostaglandin-induced abortion: gross and light microscopic findings in the placenta

A systematic gross and light microscopic study was done of 60 placentas, spontaneously delivered following induction by intra-amniotic PGF2alpha administration. The main findings were: high incidence of marginal and basal decidual hemorrhage, widespread degenerative changes in the decidua and chorionic villi, intervillous congestion and thrombosis and significant underfilling of the fetal vasculature. These changes are discussed in terms of the possible factors underlying the mechanism of prostaglandin-induced abortion.