Effects of misoprostol on uterine contractility following different routes of administration

The effect of misoprostol administered by different routes on pregnant uterine contractility was investigated.

Thirty-two women with a pregnancy between 8 and 11 weeks of gestation requesting termination of pregnancy were recruited. Misoprostol was administered either orally (0.4 mg), vaginally (0.4 mg) or sublingually (0.2 or 0.4 mg) according to consecutive allocation. Intrauterine pressure was recorded using a Grass polygraph connected to a pressure transducer 30 min before misoprostol was given and for 4 h thereafter. At the end of the recording, suction curettage was performed.

The first effect observed was an increase in uterine tonus, which occurred after a significantly shorter time following oral (7.8 min) and sublingual (10.7-11.5 min) than after vaginal (19.4 min) treatment. The time to maximum tonus elevation was also significantly shorter (39.5, 47.1-51.7 and 62.2 min for the three groups respectively). Regular uterine contractions developed in all subjects following sublingual and vaginal administration but not after oral administration. The increase in uterine activity measured in Montevideo Units was significantly higher after 2 h and thereafter for sublingual and vaginal treatment than for oral misoprostol.

Based on recording of uterine activity, sublingual misoprostol acts as rapidly as oral treatment, while development of contractions was similar to that seen following vaginal administration.