The effect of relcovaptan (SR 49059), an orally active vasopressin V_1a receptor antagonist, on uterine contractions in preterm labor

Abstract

Relcovaptan (SR 49059) is a non-peptide, orally active vasopressin V_1a receptor inhibitor. The effect on uterine contractions in 18 women with preterm labor in pregnancy weeks 32–36 was assessed in a double-blind investigation. The inclusion criterion was at least four regular uterine contractions over 30 min as measured by external tocodynamometry. Twelve patients received at random a single oral dose of 400 mg relcovaptan and six received placebo, and contractions were monitored up to 6 h thereafter. Rescue medication (β-adrenoceptor-stimulating drug) was allowed after 2 h. Before drug administration a mean ( ± SE) of 8.2 ± 1.4 and 9.7 ± 1.6 contractions/30 min were recorded in the relcovaptan- and placebo-treated groups, respectively. In the former group, the frequency of uterine contractions started to decrease within the first half hour, and 1.5–2 h after dosing it was steady at 3.2 ± 0.9 contractions/30 min. Correspondingly, after placebo, 7.8 ± 2.2 contractions/30 min were recorded, a statistically significant difference (p = 0.017). The activity in the relcovaptan-treated women remained low, whereas in the placebo group inhibited uterine contractions were observed only in women receiving ‘rescue’ tocolytic treatment. It is concluded that relcovaptan inhibits preterm labor.

• Preterm labor
• vasopressin V1a receptor
• oxytocin receptor
• antagonist