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R L Wynn

Publications and source records attributed to R L Wynn.

At least 73 records · Page 4Linked to original sources
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Amoxicillin update.

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Amoxicillin↗
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GABAmimetics diminish antinociception of meperidine under conditions which enhance other opioid mu-agonists.

This study investigated the effects of pretreatment with muscimol (GABA-agonist) or diazepam (indirect GABAmimetic) on i.v. meperidine, fentanyl, alphaprodine and morphine, using rabbit tooth pulp and mouse hot plate assays. A previous study reported that the ED50 values for fentanyl in rabbits were significantly lowered by 0.25 mg/kg of muscimol (13.8 to 1.8 micrograms/kg) and by 1.5 mg/kg of diazepam (13.1 to 1.1 micrograms/kg). ED50 values for meperidine in rabbits in this study were increased by muscimol (1.2 to 3.2 mg/kg) and diazepam (1.5 to 3.1 mg/kg). ED50 values for fentanyl in mice were significantly lowered by 0.25 mg/kg of muscimol (23.0 to 8.9 micrograms/kg) and 1.0 mg/kg of diazepam (23.3 to 12.8 micrograms/kg). ED50 values for meperidine in mice were significantly increased by muscimol (2.1 to 5.0 mg/kg) and diazepam (2.0 to 4.8 mg/kg). ED50 values for alphaprodine and morphine were significantly lowered by muscimol and diazepam in mice. A higher dose of muscimol (1.0 mg/kg) had no effect on the ED50 values of meperidine in mice. The antinociception of a submaximal dose of meperidine in rabbits was significantly reduced by a 10 min pretreatment with i.v. diazepam (1.5 mg/kg) at 15, 20, 30 and 45 min after i.v. meperidine. The antinociception of a submaximal dose of fentanyl in rabbits was significantly increased by a 10 min pretreatment with i.v. diazepam (1.5 mg/kg) at 5, 10, 15 and 20 min after i.v. fentanyl. Pretreatment with 0.1 mg/kg of scopolamine enhanced the antinociceptive effect of a submaximal dose of fentanyl in both animal models. Diazepam reduced the antinociception produced by the combination scopolamine-fentanyl to that of fentanyl-vehicle control in both animal models. Pretreatment with 0.1 mg/kg of scopolamine did not change the magnitude of antinociception of a submaximal dose of meperidine in rabbits. Since meperidine possesses inherent anticholinergic activity, it is suggested that this anticholinergic activity may be involved in the reduction effects by muscimol and diazepam.

Alphaprodine↗
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Opioid analgesics.

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Analgesics, Opioid↗
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Low dose naloxone enhances buprenorphine in a tooth pulp antinociceptive assay.

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. Naloxone 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 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.

Analgesics↗