Local anesthetics inhibit uterine activity in vitro - Possible application on preterm labor prevention and treatment

Objective: Analysis of the effects of local anesthetics upon the gravid uterus. Methods: Isolated strips of pregnant-rat myometrium were placed within tissue baths. Muscular activity was then recorded by a force transducer, at cumulative concentrations of either procaine, lidocaine, or ropivacaine. Results: The effects of myometrial activity were non-monotonic. At lower concentrations, an increase in contraction frequency was noted, concomitant with a depression in amplitude. As the concentrations increased, both amplitude and frequency were depressed until, eventually, activity was abolished. Conclusions: Local anesthetics administered in situ consistently inhibit or completely arrest overall myometrial activity. These agents may prove clinically useful in pre-term labor management, if administered locally to the myometrium via suitable slow release drug delivery systems, warranting further trials in vivo. Copyright (C) 2003 S. Karger AG, Basel.