Midtrimester abortion induced by serial intravaginal administration of prostaglandin E2 suppositories in conjunction with a contraceptive diaphragm

Midtrimester abortion was successfully induced in a series of 20 patient by intra-amniotic instillation of 15(S)-15-methyl-prostaglandin F_2α with a mean abortion time of 17.78 hours. The patients in this study were divided into two groups, Groups I received on initial dose of 2.5 mg 15-ME-PGF_2α and aborted in a mean time of 16.26 hours. The patients in Group II received 3.0 mg 15-ME-PGF_2α and aborted in a mean time of 18.94 hours. There was no significant difference in the abortion time, occurrence of side effects or the initiation of uterine activity between Group I and Group II. Parous patients aborted somewhat faster than nulliparous patients but this difference was not significant. In this study 80% of the patients aborted in 24 hours or less, and the intra-amniotic instillation of 15-ME-PGF_2α was an effective abortifacient technique from the 15th to the 23rd week of gestation. The uterine response to intra-amniotic instillation of 15-ME-PGF_2α was characterized by the gradual appearance of low amplitude, high frequency contractions accompanied by a rise in baseline intrauterine tonus. Uterine activity developed gradually and peaked at 1:50 hours after intra-amniotic instillation of 15-ME-PGF_2α. In this small series 15-ME-PGF_2α administered via intra-amniotic instillation did not appear to have a distinct advantage over the naturally occurring PGF_2α administered by the same method for the induction of midtrimester abortion; a larger series is indicated to define the advantages of either technique.     

Midtrimester abortion induced by serial intravaginal administration of prostaglandin E2 suppositories in conjunction with a contraceptive diaphragm.

Midtrimester abortion was successfully induced in 68 of 69 patients with serial intravaginal administration of prostaglandin E2 suppositories behind a contraceptive diaphragm. The mean abortion time for the successful inductions was 13.07 hours; multiparous patients aborted somewhat faster, mean 12.72 hours, as compared to nulliparous patients, mean 14.22 hours. In 36 patients the PGE2 suppositories were placed behind an intact diaphragm and the mean abortion time was 14.89 hours. In 33 patients the PGE2 suppositories were placed behind a diaphragm modified by having an opening incised in the center, the mean time in these patients was 11.96 hours. Of the 68 successful abortions 59% of the patients aborted in 12 hours or less and 88% aborted within 24 hours. The most frequently encountered side effect was temperature elevation of 2 degrees F or higher which occurred in 68% of the patients. Temperatures returned to normal levels within 4 to 6 hours after the last adminstration of PGE2. Gastrointestinal side effects occurred in 45% of patients, but these side effects were well tolerated and did not require termination of drug administration in any of the patients. Intravaginal administration of PGE2 suppositories is a very effective abortifacient technque during the midtrimester, however the use of PGE2 in conjunction with a diaphragm did not appreciabley improve the technique although the amount of drug administered and the incidence of side effects was somewhat lower than when the PGE2 suppositories are used alone. If a diaphragm is to be used, a modified diaphragm is indicated since it simplifies the clinical management of the abortion, eases administration of the suppositories and permits a more accurate estimation of cervical changes, vaginal bleeding and abortion.     

Prostaglandin E2 induced abortion with vaginal suppositories in a contraceptive diaphragm

Prostaglandin E₂, 20 mgm vaginal suppositories were administered to two groups of women seeking termination of pregnancy. One group had the suppository inserted inside a contraceptive diaphragm. Statistical comparisons were carried out for instillation to abortion time, side effects, and intra-uterine pressure parameters. The usage of the diaphragm significantly reduced side effects, and resulted in an instillation to abortion time of 12.8 ± 2.3 hours with no failures. The quantitative analysis of the uterine pressure recordings revealed activity significantly different than that seen with intra-amniotic or extra-ovular PG F_2α. The development of uterine activity simulates that of normal labor in that elevation of resting pressure does not occur and maximum active pressure evolves slowly.     

Prostaglandin E2 induced abortion with vaginal suppositories in a contraceptive diaphragm

PGE2 (prostaglandin E2), 20 mgm vaginal suppositories were administered to 2 groups of women seeking termination of pregnancy. 1 group had the suppository inserted inside a contraceptive diaphragm. Statistical comparisons were carried out for instillation to abortion time, side effects, and intrauterine pressure parameters. The usage of the diaphragm significantly reduced side effects, and resulted in an instillation to abortion time of 12.8 + or - 2.3 hours with no failures. The quantitative analysis of the uterine pressure recordings revealed activity significantly different than that seen with intraamniotic or extraovular PGF2alpha. The development of uterine activity simulates that of normal labor in that elevation of resting pressure does not occur and maximum active pressure evolves slowly.     

Controlled trial of induction of labor by vaginal suppositories containing prostaglandin E2

A group of 84 women at 39 – 43 weeks of pregnancy were randomly allocated to a blind trial of induction of labor with vaginal suppositories containing inert material or either 0.2 mg or 0.4 mg of prostaglandin E₂. The suppositories were self-administered every two hours during waking hours on two successive days until labor started or 15 had been used. Side-effects were absent. Labor was established within 48 hr of insertion of the first suppository in 9.3% of control patients, 65.4% of those treated with 0.2 mg PGE₂ and 85.7% of those treated with 0.4 mg PGE₂. The mean Apgar scores in the three groups were the same. The mean total dose of PGE₂ were 2.0 mg (0.2 mg group) and 2.3 mg (0.4 mg group). It is concluded that vaginal PGE₂ is an effective and acceptable method of inducing labor at term.     

Serum relaxin levels in prostaglandin E2 induced abortions

Relaxin, a peptide hormone produced only by the corpus luteum of pregnancy, can be used as a marker of luteal function in human pregnancy. Serum immunoreactive relaxin levels were measured serially in six women having second trimester abortions induced with intravaginal prostaglandin E2 (PGE₂) suppositories. All patients aborted within 17 hours of the first suppository. No significant changes were detectable in serum relaxin levels in any of the patients. It is concluded that PGE₂ does not interfere with the corpus luteum's ability to secrete relaxin in the second trimester of human pregnancy.     

Avian oviduct motility induced by prostaglandin E1

Oviduct segments from infundibulum, magnum, uterus, uterovaginal junction and vagina of actively laying hens at preoviposition time were tested for their contractile reaction to prostaglandin E₁ by or methods. Maximum stimulatory response was observed from the muscular strips of the proximal oviduct segment (infundibulum) and a complete relaxation was recorded from the distal part (vagina) at molar concentrations of 1.4 × 10⁻⁷, 3.4 × 10⁻⁷ and 7.0 × 10⁻⁷. The uterine strips reacted with a stimulatory response at higher concentrations (1.4 × 10⁻⁶ and 2.8 × 10⁻⁶ moles), but lacked any significant change at lower concentrations. The uterovaginal muscular strips showed a mild but prolonged inhibitory response, while the magnum responded with a significant increase in the luminal pressure when tested . It is concluded that PGE₁ exerts a stimulatory effect on the uterus to initiate transport of the egg to subsequent segments (uterovaginal junction and vagina), which relax under PGE₁ influence and allow passage of the egg by pressure differences.     

Prostaglandin E2 in a diaphragm a further note

In a previous study we reported that the administration of Prostaglandin E₂ suppositories in a vaginal contraceptive diaphragm enhanced the effectiveness of the drug and reduced the incidence of side effects by 50%.1 Since that study there have been two reports which could not verify our experiences. 2, 3 Therefore we attempted to look at the problem again.     

Bone remodelling induced by physical stress is prostaglandin E2 mediated

In vitro cultured bone cells were found to be responsive to hormones and physical forces. A simple device has been developed which enables the direct application of physical forces to tissue culture dishes to which cells are firmly attached. The physical forces created a deformation of the dish. It was found that prostaglandin E₂ synthesis underwent a rapid increase, reaching a maximum after 20 min and then declined. Concurrent with the increase in prostaglandin E₂ was an increase in cyclic AMP production, having a maximum around 15 min. The increase in cyclic AMP was blocked by indomethacin, the prostaglandin E₂ synthesis inhibitor, indicating the dependence of cyclic AMP production on the de novo synthesis of prostaglandin E₂. Prostaglandin E₂ added to cells mimicked the effect of physical forces on the production of cyclic AMP. The increase in cyclic AMP resulted from an early rise in adenyl cyclase activity (within 5 min) and a later (10 min) increase in phosphodiesterase activity. The same physical forces also stimulatedthe incorporation of thymidine into DNA after 24 h. On addition of prostaglandin E₂ the increase in DNA synthesis was also mimicked. Pretreatment of the cells with indomethacin abolished the effect of physical forces on DNA synthesis.The results suggest a stimulus receptor mechanism for physical forces which, like hormonal effectors, are mediated by prostaglandins and stimulate cyclic AMP and DNA synthesis.We believe that physical forces stimulate bone remodelling through such a stimulus receptor system, mediated by prostaglandins.     

Hypercalcemia induced by prostaglandin E2 in thyroparathyroidectomized but not intact rats

Prostaglandin E₂ was infused into the thoracic aorta of thyroparathyroidectomized (TPTX) and intact rats. Circulating calcium increased significantly in the TPTX group by 30 minutes and reached an increment of

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by 90 minutes. No calcium increments were observed in the intact rats. It is postulated that prior failures to demonstrate hypercalcemia during PGE₂ infusion may have been due to calcitonin counterregulation.     

Induction of midtrimester abortion by serial intravaginal administration of 15(S)-15-methyl-prostaglandin F2α (THAM) suppositories

Midtrimester abortion was successfully induced in 13 of 22 patients by serial intravaginal administration of 15(S)-15-methyl-prostaglandin F_2α (THAM) suppositories. Nine patients, 4 nulliparas and 5 multiparas, failed to abort after 24 hours of prostaglandin administration and a concomitant infusion of oxytocin was initiated. Seven of the nine patients aborted within 7 hours of the combined therapy and one patient on methadone maintainence aborted after 17.5 hours of combined therapy, 41.5 hours after the first dose of prostaglandin. A single patient failed to abort, despite the concomitant prostaglandin-oxytocin administration and underwent surgical evacuation. The mean abortion time for the 21 successful abortions was 22.56 hours. Nulliparous patients aborted somewhat faster, mean 21.79 hours, than multiparous patients, mean 23.80 hours, but this difference was not statistically significant. In this study, one patient aborted in less than 12 hours, and 62% of the successful cases aborted within 24 hours. The plasma levels of 15-ME-PGF_2α were analyzed by radioimmunoassay in 10 patients. Plasma prostaglandin levels rose significantly 30 minutes after the insertion of the first suppository, but there was a wide variation in levels from patient to patient. It was observed that the 2 patients with the highest levels had the fastest abortion times and episodes of gastro-intestinal side effects appeared related to a rise in prostaglandin levels. Sixty-four percent of the patients in this study had no gastro-intestinal side effect related to prostaglandin administration.     

Molecular conformation of prostaglandin E2

The crystal and molecular structure of prostaglandin E₂ (PGE₂) has been determined by X-ray diffraction. The compound crystallizes in the triclinic space group P1 with Z = 1 and , , , α = 87.347°, β = 94.042°, and γ = 91.010°. Gauche-gauche interactions appear in both side chains. The efficient molecular packing and hydrogen bonding network appears to stabilize the observed molecular conformation.     

Stimulation of bone formation by prostaglandin E2

We examined the effect of prostaglandin E₂ (PGE₂), in the presence or absence of cortisol, on bone formation in 21-day fetal rat calvaria maintained in organ culture for 24 to 96 h. [³H]Thymidine and [³H] proline incorporation were used to assess DNA and collagen synthesis, respectively. Changes in dry weight and DNA content were assessed after 96 h.PGE₂ (10⁻⁷ M) stimulated both DNA and collagen synthesis in calvaria. The effect on DNA synthesis was early (24 h), transient and limited to the periosteum. Collagen synthesis was stimulated at a later time (96 h), predominantly in the central bone. Cortisol (10⁻⁷ M) inhibited DNA and collagen synthesis. The addition of PGE₂ reversed the inhibitory effects of cortisol on DNA synthesis and content and increased collage synthesis in central bone to levels above control untreated cultures.We conclude that PGE₂ has stimulatory effects on bone formation and can reverse the inhibitory effects of cortisol. Hence the effects of cortisol may be mediated in part by their ability to reduce the endogenous production of prostaglandins.     

Teratological studies with prostaglandin E2 in chick embryos

Prostaglandin E₂ (20–100 μg) was lethal to a relatively high percentage of chick embryos when administered at 48 hours incubation; no such effect was observed after 72 hours incubation. A relatively high incidence of abnormal embryos, which increased with the dose-levels of prostaglandin, was induced at both 48 and 72 hours incubation compared to the controls. However, this difference was statistically significant only in embryos treated with 100 μg prostaglandin at 48 hours incubation. The embryos showed no signs of growth retardation.     

Termination of pregnancy with prostaglandin E2 methyl ester

Prostaglandin E₂ methyl ester was several times more potent than PGE₂ (free acid) in stimulating the human uterus at mid-pregnancy, when administered by the intra-amniotic, extra-amniotic and intravaginal routes. At effective abortifacient dosage, however, the frequency and intensity of gastrointestinal, central nervous and cardiovascular side effects were high. This precluded further clinical trials with the compound. It is suggested that rapid entry of the drug into the systemic circulation takes place.     

Radioimmunoassay of 15-keto-prostaglandin E2 in peripheral plasma after oral administration of prostaglandin E2 tablets used for induction of labour

A radioimmunoassay of the 15-keto-metabolite of prostaglandin E₂ has been developed. The details of the assay are described. Using unextracted plama, serial measurements of 15-keto-PGE₂ have been carried out every 15 minutes for 3 hours in 9 women ingesting 0.5 mg PGE₂ oral tablets used for the induction of labour.     

Labour induction using buccal prostaglandin E2

Prostaglandins may remain in the circulation for some two hours after oral therapy and any resultant hypertonus may be difficult to treat in these circumstances. Buccal administration based on the concept that tablets could be discarded should this occur, has been evaluated in 30 patients. Effective uterine stimulation occured in 90% of subjects receiving a dose of 1mg hourly. No hypertonus occured but two patients had a prolonged contraction on a single occasion during labour. The fact that the tablets dissolve rapidly and in addition produce an unpleasant taste with a high incidence of nausea and vomiting, indicates buccal prostaglandins do not have advantages over alternative methods of oxytocic administration.     

Correlation between cyclic AMP and LH release following prostaglandin E2 administration

Five min following a single iv injection of PGE₂ into ovariectomized mature rats pretreated with estrogen and progesterone, plasma LH and plasma and pituitary cyclic AMP levels were raised significantly. A close correlation was observed between increased pituitary cyclic AMP contents and release of plasma LH. The average level of cyclic AMP in the anterior pituitary and plasma cyclic AMP increased significantly, while the circulating plasma LH level was not changed at 1 min after PGE₂ injection. Plasma LH level increased at 2 min after PGE₂ and reached a maximum level at the above-mentioned time. This is consistent with hypothesis that increased release of hormone is a consequence of increased pituitary cyclic AMP content.     

Tissue differences in vascular permeability induced by leukortriene B4 and prostaglandin E2 in the rat

The activity of synthetic LTB₄ and PGE₂, in increasing vascular permeability was tested simultaneously in seventeen different organs in the rat. Rats were injected in the aortic arch through a cannula in the carotid artery with ¹²⁵-I-albumin, ⁵¹Cr-erythrocytes, and ⁵⁷Co-EDTA. The rats were then injected through the carotid artery cannula with LTB₄, PGE₂ or a combination of LTB₄ and PGE₂. Eight minutes later the rats were killed and the activity of ¹²⁵I, ⁵¹Cr, and ⁵⁷Co measured in different organs. Changes in vascular permeability were infered from changes in the ratios of the isotope activities. LTB₄ (15 μg/kg) induced enhanced permeability in caecum, small bowel, skin, fat pad, stomach, pancreas, and aorta, but not in the heart, brain, colon, testes, diaphragm, forelimb, cremaster muscle, lung, kidney or eye. A lower dose of LTB₄, 3 μg/kg, enhanced vascular permeability in caecum, small bowel, skin, stomach, and aorta. PGE₂ (1 μg/kg) enhanced vascular permeability only in the caecum. A combination of LTB₄ (3 μg/kg) and PGE₂ (1 μg/kg) was more potent than either alone. Rats depleted of neutrophils with anti-neutrophil serum were less sensitive to LTB₄ than intact rats. These findings suggest that the vasculatures of different tissues in the rat vary markedly in their susceptibility to LTB₄ induced increases in permeability.