Double-blind placebo-controlled trial of baclofen, alone and in combination, in patients undergoing voluntary...

This study evaluated the analgesic efficacy of baclofen in relation to specific pain stimuli in 83 women (27 nulliparas and 56 multiparas) undergoing voluntary abortion (clamping of the cervix and dilatation and curettage). The patient population was divided into five treatment groups as follows: group 1, placebo; group 2, baclofen, 0.3 mg/kg, administered intravenously (IV); group 3, baclofen, 0.6 mg/kg IV; group 4, baclofen, 0.3 mg/kg IV, and fentanyl, 1.5 mg IV; and group 5, baclofen, 0.3 mg/kg IV, and diazepam, 5 mg given orally and 5 mg IV. In each case the surgical intervention was started using analgesia only. When the first sensation of pain was recorded, a paracervical anesthetic block was performed to provide pain relief for completion of the operation. The results showed that baclofen had significantly better analgesic properties than did placebo, with no important side effects. Its analgesic action seemed to be dose-dependent, since better results were obtained with the higher dose. The analgesic effect was slightly potentiated when baclofen was combined with fentanyl, but not when it was combined with diazepam. Factors independent of the pain stimuli and drugs used--the most important being parity--influenced the results.