LOW-DOSE NALOXONE ENHANCES BUPRENORPHINE IN A TOOTH-PULP ANTINOCICEPTIVE ASSAY

  • 1 January 1988
    • journal article
    • research article
    • Vol. 291, 229-237
Abstract
Low dose naloxone was reported to produce analgesia of long duration in patients who received buprenorphine. A rabbit tooth pulp antinociceptive model was utilized to evaluate a possible interaction of buprenorphine and naloxone. Naloxone (0.001 mg/kg i.v.) 210 min after buprenorphine (0.10 mg/kg i.v.) significantly increased the % MPE from 48 .+-. 5% to 78 .+-. 6 %. This increased activity occurred within 90 min after naloxone injection and had a duration of 2 hr. Naloxone, 0.1 mg/kg, or saline 0.1 ml/kg did not increase nor reduce the buprenorphine antinociceptive effect. Nalozone alone (0.001 mg/kg) produced a peak antinociceptive effect of 43 .+-. 14 % MPE which was significantly greater than that of the saline control group. Using a graded dose response paradigm in the rabbit tooth pulp model, the graded dose response paradigm in the rabbit tooth pulp model, the graded dose response curve of buprenorphine was significantly shifted upwards after preadministration of 0.001 mg/kg naloxone. The slopes of both the ascending and descending limbs of the biphasic buprenorphine dose response curves were not significantly different. The peak % MPE achieved by buprenorphine in the presence of 0.001 mg/kg naloxone (62 .+-. 8%) was significantly greater than the buprenorphine-saline control (23 .+-. 4%). It appears that a low dose of naloxone produces antinociception which enhances that of buprenorphine.