Induction of labour by extra-amniotic prostaglandins

Induction of labour with vaginal prostaglandin E2 pessaries

Wax-based pessaries, each containing 3 mg of prostaglandin E2 (PGE2), were administered intravaginally for the induction of labour. The induction to delivery intervals were shorter than those in a control group induced by amniotomy and intravenous oxytocin. There was a remarkable reduction in the Caesarean section rate from 12 per cent in the control group to 2.4 per cent in the study group in primiparae, and from 8 per cent to 1.6 per cent in multiparae. Side effects associated with the PGE2 were rare, as were complications.

The use of prostaglandin gel in obstetrics and gynecology

The use of prostaglandin gel for therapeutic termination of second trimester pregnancy, the management of intrauterine fetal death, ripening of the cervix and induction of labour is reviewed. For these indications, prostaglandin gel is acceptable to patients, effective, and has low incidence of side effects and complications.

Fetal effects of cervical ripening with extra-amniotic prostaglandin E2 in gel

A gel containing 0.5 mg prostaglandin E2 (PGE2) was extra-amniotically instilled 90 clinically normal gravidae at term, for ripening of the cervix before elective induction of labor by amniotomy and intravenous PGE2. An acceptable increase in the Bishop score was noted to have occurred in 87/90 women, when assessed eight hours after administration of the gel; 14 of these women were then in established labor, which progressed uneventfully. Four of the 90 subjects required cesarean section for cephalopelvic disproportion. No adverse maternal or fetal effects of the procedure were detected under careful clinical, electronic and biochemical monitoring. However, epidural anesthesia adversely influenced the acid-base equilibrium of the fetus.

Ripening of the cervix with extra-amniotic prostaglandin E2 in viscous gel before induction of labour

A metohod of extra-amniotic prostaglandin administration to achieve ripening of the cervix as a preliminary to induction of labour is described. Compared with a control group the method achieved a 25 per cent reduction in the length of the induced labour, a fall in the incidence of maternal pyrexia and fetal distress, an improvement in neonatal condition of the infants and a reduction in the need to resort to Caesarean section.

Nucleophilic addition of bisulfite ion to prostaglandins E2 and A2: implication in aqueous stability

Evidence is presented to indicate that the bisulfite ion (HSO3-) adds across the C-9 carbonyl group of dinoprostone (prostaglandin E2) and across the delta 10,11- bond of prostaglandin A2. At room temperature, the apparent equilibrium constant, determined by phase solubility analysis, circular dichroism, UV spectroscopy, and partitioning, for the formation of the bisulfite adduct of dinoprostone is about 7.5 M-1 at neutral pH. From this result and a free energy relationship reported in the literature for the thermodynamics of nucleophilic addition to carbonyl groups, it is concluded that the chemical reactivity of the C-9 carbonyl group of dinoprostone is not high enough to improve aqueous stability through reversible one-step nucleophilic reactions. However, from a series of kinetic experiments, it is concluded that the equilibrium is extremely favorable for the formation of the bisulfite adduct of prostaglandin A2 over pH 4-8 at room temperature. The second-order rate constant for the attack of sulfite ion (SO3 2-) to prostaglandin A2 is 1.75 sec-1 M-1.