Antinociceptive/anti-edema effects of liposomal morphine during acute inflammation of the rat paw.
We evaluated the anti-edema/antinociceptive effects of subcutaneous free and liposomal morphine in rats with carrageenan-induced inflammation of the paw. We assessed antinociception by the paw pressure test and edema by plethysmography. Unilamellar liposomes (150-200 nm) with 0.3% morphine hydrochloride were used; encapsulation significantly reduced the rate for release of morphine in vitro. During inflammation, the antinociceptive potency of free, but not liposomal morphine increased 2.5 times; moreover, duration of the effects was prolonged by encapsulation (p < 0.001). The anti-edema effects of liposomal morphine were more pronounced (p < 0. 001) and of longer duration (p < 0.05). All the effects were reversed by naloxone. The results show that morphine encapsulation enhances the anti-edema effects and prolongs antinociception.
Planas
E
E
Department of Pharmacology, University of Barcelona, Odontology School, Feixa LLarga s/n, Hospitalet de LLobregat, Barcelona, Spain.
Sánchez
S
S
Rodriguez
L
L
Pol
O
O
Puig
M M
MM
D000701:Analgesics, Opioid / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D002351:Carrageenan; D004337:Drug Carriers; D004487:Edema / Q000139:chemically induced / Q000188:drug therapy*; D008081:Liposomes; D008297:Male; D009020:Morphine / Q000494:pharmacology / Q000627:therapeutic use*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
D000701:Analgesics, Opioid; D004337:Drug Carriers; D008081:Liposomes; D009292:Narcotic Antagonists; D009270:Naloxone; D009020:Morphine; D002351:Carrageenan