Double-blind comparison of carbetocin versus oxytocin in prevention of uterine atony after cesarean section

Objective: The goal of this study was to compare carbetocin, a long-acting oxytocin analog, with oxytocin in the prevention of uterine atony after cesarean section. Study Design: We enrolled 694 patients undergoing elective cesarean section in a Canadian multicenter, double-blind, randomized clinical trial. We compared the effect of a single 100 μg dose of carbetocin with that of a standard 8-hour infusion of oxytocin. The primary outcome was the proportion of patients requiring additional oxytocic intervention for uterine atony. A variable sample size, sequential design was used. Results: The overall oxytocic intervention rate was 7.4%. The odds of treatment failure requiring oxytocic intervention was 2.03 (95% confidence interval 1.1 to 2.8) times higher in the oxytocin group compared with the carbetocin group, respectively, 32 of 318 (10.1%) versus 15 of 317 (4.7%), P < .05. Conclusions: Carbetocin, a new drug for the prevention of uterine atony, appears to be more effective than a continuous infusion of oxytocin and has a similar safety profile. (Am J Obstet Gynecol 1999;180:670-6.)