Efficacy of cyclic and extended regimens of ethinylestradiol 0.02 mg -levonorgestrel 0.09 mg for dysmenorrhea: A placebo-controlled, double-blind, randomized trial.

The Cyclic and Extended regimens of NPC-16 significantly reduced dysmenorrhea severity compared to placebo. The Extended regimen was superior to cyclic regimen in reducing the dysmenorrhea.