Local application of ketocaine for treatment of referred pain in primary dysmenorrhea.

In a randomized, double-blind cross-over study the effect on referred pain of the local anesthetic, ketocaine, was evaluated in 23 women suffering from primary dysmenorrhea. Ketocaine was administered in compresses containing 1 g ketocaine in a 10 per cent ethanol solution. The investigation comprised two consecutive menstrual periods. During one, the patient received ketocaine compresses, and during the other placebo compresses, i.e. compresses without ketocaine. The compresses were applied to the skin area where the patient experienced the most intense pain. When receiving ketocaine compresses, 19 of the 23 patients reported good or moderate pain relief. The effect was recognized within 30 to 60 minutes and lasted for a mean of 3 hours (range 1.5--5 h). Only four of the patients reported relief of pain when receiving placebo compresses. This effect ceased when the compresses were removed. No general side effects were registered. However, erythema at the site of compress application was more often observed after ketocaine than after placebo compresses.