In situ inhibition of uterine activity by indomethacin: possible relevance to preterm labor prevention after fetal surgery

Purpose

This report is an analysis of the effects of local indomethacin delivery on uterine activity in vitro.

Methods

Isolated strips of time-dated pregnant rats’ myometrium were placed within controlled tissue baths. Spontaneous muscular activity was recorded by a force transducer connected to a polygraph at cumulative concentrations of indomethacin. Statistical analysis was by single-factor analysis of variance (ANOVA), with P values of less than .05 considered significant.

Results

Within a narrow concentration range, the effects of indomethacin on frequency and amplitude of myometrial contractions were nonmonotonic, with an increase in frequency at levels that began to depress amplitude. However, both amplitude and frequency were significantly depressed and eventually totally abolished at most concentrations studied (P < .05).

Conclusions

Indomethacin administered in situ consistently inhibits or completely arrests overall myometrial activity. The concept of local myometrial delivery of indomethacin, possibly via slow release systems, may prove clinically useful as an adjuvant to its systemic administration in preterm labor prevention after fetal surgery, warranting further trials in vivo.