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A new gel-formulation for intracervical application of prostaglandin E2 (PGE2) has been prepared. As a vehicle for the gel a cross-link starch polymer is used. PGE2 substance is added to the starch polymer and after homogenization and lyophilization a PGE2 powder is obtained. The powder can be stored at room temperature for more than four months without inactivation of the prostaglandin. Before clinical application a few ml of saline is added to the powder giving, within 30 seconds, an easily-handled ready to use PGE2-gel. Chemical analysis by spectrophotometric technique reveals that the amount of unchanged PGE2 is the same in the new gel-formulation as in a conventional cellulose gel. In a randomized double-blind study the new PGE2-gel was intracervically applied to twenty nulliparae before abortion by dilatation and evacuation (D & E). Ten women were given a gel containing 0.25 mg PGE2 (PGE2-gel) and ten a gel without PGE2 (placebo gel). It was found that the PGE2-gel, in contrast to the placebo gel, produced a rapid ripening of the cervix facilitating the subsequent D & E. No adverse systemic or local reactions were found during or after the treatment.

In 54 patients with an unripe cervix in late third trimester, in which gestational age had been properly determined by repeated ultrasound scannings, labor was induced by intracervical application of 0.5 mg PGE2 in viscous gel. It was found that the outcome of the induced labor was not related to the gestational duration, but to the pre-inductive cervical score. Thus, the number of successful inductions was smaller and induction-delivery time longer, the lower the cervical score. Moreover, instrumental deliveries occurred most frequently in nulliparous women, with a low pre-inductive cervical score. Taking into consideration the difficulties of labor induction in the present type of patient, the overall proportion of instrumental deliveries (17%, including 7% cesarean sections) was low. No maternal or fetal side effects were observed. It is concluded that intracervical application a small dose of PGE2 in gel can be recommended for cervical priming and labor induction in pre- and post-term pregnancy.

Prostaglandin E2 (PGE2) suspended in a viscous gel was deposited intracervically to 115 patients at term with an unripe cervix. 45 of these patients were given a single dose of 1.0 mg PGE2, whereas the remaining 70 received only half that dose, i.e. 0.5 mg. Irrespective of dose greater than 60 per cent of the patients were induced into labor and delivered without further stimulation within less than 24 hours. The mean induction delivery time was 10 hours. In the remaining patients a considerable ripening of the cervix was registered. Hypercontractility did occur in one patient given 1.0 mg PGE2, otherwise no maternal side effects were observed. There were no adverse effects on the fetuses. The number of instrumental deliveries was 19 per cent including 9 per cent cesarean sections. It is concluded that locally applied PGE2-gel can be used to produce ripening of the cervix and/or induce labor in patients at term with an unripe cervix. Since there was practically no difference in efficiency between the two doses but one case of hyperstimulation in patients given 1.0 mg PGE2, the smaller dose, i.e. 0.5 mg is recommended.

In a randomized double-blind study a viscous gel, containing 0.25 mg prostaglandin E2 (PGE2-gel) or without prostaglandin (placebo gel), was applied intracervically in twenty-two nulliparous patients just before termination of early pregnancy by dilatation and evacuation (D & E). Within twelve hours a marked ripening of the cervix was found in all the eleven patients receiving PGE2-gel. Thus, a significant change in cervical dilatation from mean 5.4 mm to mean 10.7 mm occurred. Furthermore, a considerable softening of the cervix was registered. In the eleven patients receiving placebo gel, no significant changes in cervical dilatation or consistency were found. The subsequent D & E was easily performed in all patients treated with PGE2-gel. However, in three of the patients given placebo gel, D & E was difficult to carry out because of an unfavorable cervical state. To eliminate or decrease myometrial activity the calcium antagonist nifedipine was given orally to eight patients at application and five hours after application of 0.25 mg PGE2-gel. None of the patients recognized uterine contractions. However, also in these patients significant changes in cervical consistency and dilatation occurred within twelve hours. No side effects of the treatment were observed. It is concluded, that a preoperative, intracervical single application of 0.25 mg PGE2 seems to be useful to ripen the unfavorable cervix before subsequent termination of early pregnancy by D & E.

A survey of connective tissue in general and human cervical connective in particular is presented. It is concluded that about 90% of the human cervix consists of fibrous connective tissue which, according to the composition of the collagen and the proteoglycans, is very similar to that in skin and sclera. The high activity of collagenase probably gives the cervical connective tissue from pregnant women its potential to ripen following prostaglandin treatment. Electron microscopical examination has revealed an increased amount of amorphous substance after such treatment. This may be caused partly by degraded collagen fibers and partly by newly synthesized proteoglycans.

The methods used to date to ripen the unfavorable cervix during pregnancy have considerable disadvantages, chiefly from the practical point of view. Intracervical application of a small dose (0.5 mg) of prostaglandin E2 (PGE2) in viscous gel is a safe, easily performed and effective method to ripen the cervix in both early and late pregnancy. A new starch-based gel seems to have solved the pharmaceutical problems associated with gel preparations used hitherto. The histological and biochemical changes induced by local application of PGE2 are similar to those occurring spontaneously during late pregnancy.