Verapamil to inhibit the cardiovascular side effects of ritodrine.

Side effects of beta-sympathomimetic drugs are of primary interest in the treatment of preterm labor. Incidence of side effects are dose-dependent, as is the efficacy of the beta-agonist in uterine relaxation. the effect of verapamil (Ca2+) inhibitor with antiarrhythmic action) on ritodrine does not modify the value of ritodrine in prolonging pregnancy, but clearly diminishes the incidence of maternal tachycardia and hypotension. The authors suggest that in the treatment of preterm labor with ritodrine infusion above 200 micrograms/min, the addition of verapamil (dosage, 80-120 micrograms/min) is useful because it substantially reduces the cardiovascular side effects associated with ritodrine hydrochloride.