Buccal or sublingual misoprostol for cervical ripening and induction of labour.

BACKGROUND: This is one of a series of reviews of cervical ripening and labour induction using standardised methodology. Misoprostol administered by the oral and sublingual routes have the advantage of rapid onset of action, while the sublingual and vaginal routes have the advantage of prolonged activity and greatest bioavailability.
OBJECTIVES: To determine the effectiveness and safety of misoprostol administered buccally or sublingually for third trimester cervical ripening and induction of labour. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group trials register (8 December 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 4, 2003), and bibliographies of relevant papers. SELECTION CRITERIA: Randomised controlled trials comparing buccal or sublingual misoprostol used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods. DATA COLLECTION AND ANALYSIS: A generic strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. Data were extracted onto standardized forms, checked for accuracy, and analysed using RevMan software. MAIN
RESULTS: Three studies (502 participants) compared buccal/sublingual misoprostol respectively with a vaginal regimen (200 microg versus 50 microg) and with oral administration (50 versus 50 microg and 50 versus 100microg).The buccal route was associated with a trend to fewer caesarean sections than with the vaginal route (18/73 versus 28/79; relative risk (RR) 0.70; 95% confidence interval (CI) 0.42 to 1.15). There were no significant differences in any other outcomes. When the same dosage was used sublingually versus orally, the sublingual route was associated with less failures to achieve vaginal delivery within 24 hours (12/50 versus 19/50; RR 0.63, 95% CI 0.34 to 1.16), reduced oxytocin augmentation (17/50 versus 23/50; RR 0.74, 95% CI 0.45 to 1.21) and reduced caesarean section (8/50 versus 15/50; RR 0.53, 95% CI 0.25 to 1.14), but the differences were not statistically significant. When a smaller dose was used sublingually than orally, there were no differences in any of the outcomes. REVIEWERS'
CONCLUSIONS: Based on only three small trials, sublingual misoprostol appears to be at least as effective as when the same dose is administered orally. There are inadequate data to comment on the relative complications and side-effects. Sublingual or buccal misoprostol should not enter clinical use until its safety and optimal dosage have been established by larger trials.