Influence of naloxone on uterine contractions in patients with primary dysmenorrhea

Abstract Dysmenorrhea is a common condition among women in childbearing age. An increased uterine contractions, resulting among others from increased vasopressin and oxitocin secretion, is considered as a main cause of the primary dysmenorrhea. The endogenous opioids play the important role in the control of oxytocin and vasopressin release from the pituitary gland. Naloxone is a selective opioid receptor antagonis. So far, there is not much data on naloxone effect on uterine contractions. The aim of study was to determine the influence of naloxone on uterine contractions in patients with primary dysmenorrhea. There were 10 female patients with primary dysmenorrhea included into the study. The uterine contractions had been recorded for 30 minutes before and 2 hours after injection of naloxone at the first day of menstruation. The intrauterine pressure recordings revealed a severe spontaneous uterine contractions, with high frequency and amplitude, at the time of dysmenorrhea. An intravenous administration of naloxone decreased uterine contractile activity and pain intensity. Naloxone acting on central nervous system decreases the uterus contractions in the patients suffering from dysmenorrhea. Unexplained mechanisms and multiple factors involved in the pathogenesis of primary dysmenorrhea indicates a need for the further studies on this subject.