Prostaglandin E2 preparations for preinduction cervical ripening. Pharmacy considerations.

The use of locally applied prostaglandin E2 (PGE2) has become a common intervention in the management of the unripened cervix in term pregnancy. The extemporaneously prepared, vaginally administered prostaglandin E2 gels are most often used clinically in the United States. Large-scale clinical trials have not been conducted with these products. The extemporaneously prepared gels are not standardized with regard to potency, purity or stability; the assessment of efficacy and safety is based on anecdotal clinical reports. PGE2 and its metabolites are eliminated rapidly from the circulation, thus plasma levels are not useful in assessing clinical efficacy. Pharmacokinetic evaluations are based on plasma levels of the stable bicyclo-metabolite of PGE2. Plasma levels resulting from exogenous administration of PGE2 cannot be distinguished from plasma levels caused by endogenous production. Available evidence supports local application of low doses of PGE2 for cervical ripening prior to labor induction. Local application may minimize undesirable systemic effects and uterine hypertonus. A cost/benefit evaluation of a commercially prepared intracervical PGE2 gel must consider several factors in addition to acquisition cost including avoidance of other more costly procedures, such as cesarean section, instrumental delivery, anesthesia, transfusions and monitoring of prolonged labor and fetal outcome, liability issues and pharmacy preparation costs.