Enhanced potency of intravenous, but not intrathecal, morphine and morphine-6-glucuronide after burn trauma.
We examined the analgesic effect of morphine (M) and its metabolite morphine-6-glucuronide (M6G) in a rat model of acute thermal trauma. M or M6G were given by intrathecal (IT) or intravenous (i.v.) routes after brief burn or sham burn delivered during inhalational anesthesia. In the sham group, M6G was significantly less potent than M when given i.v., yet tended to be more potent than M when given IT. For both drugs, thermal injury increased i.v. potency, yet decreased (for M) or displayed a trend to decrease (for M6G) It potency. The increased potency seen with i.v. but not IT opioid administration may reflect pharmacokinetic (e.g., diminished clearance) and/or pharmacodynamic responses (e.g., activation of peripheral opioid receptors) after thermal injury.
Langlade
A
A
Department of Anesthesia, Massachusetts General Hospital, Boston 02114.
Carr
D B
DB
Serrie
A
A
Silbert
B S
BS
Szyfelbein
S K
SK
Lipkowski
A W
AW
D000698:Analgesia; D000818:Animals; D002056:Burns / Q000188:drug therapy*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D007275:Injections, Intravenous; D007278:Injections, Spinal; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use*; D009022:Morphine Derivatives / Q000008:administration & dosage / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley
D009022:Morphine Derivatives; C035349:morphine-6-glucuronide; D009020:Morphine