Antinociceptive effect of meloxicam, in neurogenic and inflammatory nociceptive models in mice.
OBJECTIVE
The antinociceptive effect of the new cyclooxygenase (COX)-2 inhibitor, meloxicam, given intraperitoneally (i.p.), was assessed in different models of chemical and thermal nociception in mice.


METHODS
The analgesic effect was analysed using acetic acid-induced abdominal constriction (AA), formalin and capsaicin-induced licking, and hot-plate tests.


RESULTS
The treatment of animals with meloxicam or diclofenac (2.8-94.3 micromol/kg, i.p. 30 min prior) caused graded and significant inhibition of AA, with mean ID50 values of 7.4 and 38.0 micromol/kg, respectively. At the ID50 level, meloxicam was about 5-fold more potent than diclofenac. In the formalin test, meloxicam or diclofenac (0.8-94.3 micromol/kg, i.p. 30 min prior) also caused significant inhibition of both the early (neurogenic pain) and the late (inflammatory pain) phases of formalin-induced licking. The calculated mean ID50 values for the early phase were: 7.1 and > 94.3 micromol/kg, while for the late phase they were 2.8 and 34.5 micromol/kg, respectively, for meloxicam and diclofenac. Meloxicam also caused significant inhibition of formalin-induced oedema (p < 0.05). Meloxicam and diclofenac (0.8-314.4 micromol/kg, i.p. 30min prior) produced significant and dose-related inhibition of neurogenic nociception caused by topical injection of capsaicin, with mean ID50 values of 4.0 and 47.4 micromol/kg, respectively, but were ineffective in the hot-plate model of nociception.


CONCLUSIONS
The present study shows that meloxicam dose-dependently exhibited systemic antinociceptive action when assessed against neurogenic and inflammatory pain caused by acetic acid, formalin and capsaicin models. In contrast, when assessed in the hot-plate test, meloxicam had no significant effect. Thus, meloxicam and other COX-2 inhibitors might be useful for therapeutic intervention in the management of neurogenic and inflammatory pain.
Núcleo de Investigações Químico-Farmacêuticas, FAQFAR, Universidade do Vale do Itajaí, Brazil. adair@mbox1.univali.rct-sc.br
A R
AR
Santos
E M
EM
Vedana
G A
GA
De Freitas
D000009:Abdominal Muscles / Q000187:drug effects; D019342:Acetic Acid; D000700:Analgesics / Q000494:pharmacology*; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D002211:Capsaicin; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004008:Diclofenac / Q000494:pharmacology; D005557:Formaldehyde; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D000077239:Meloxicam; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy* / Q000209:etiology; D010147:Pain Measurement; D011930:Reaction Time / Q000187:drug effects; D013843:Thiazines / Q000494:pharmacology*; D013844:Thiazoles / Q000494:pharmacology*
D000700:Analgesics; D000701:Analgesics, Opioid; D016861:Cyclooxygenase Inhibitors; D013843:Thiazines; D013844:Thiazoles; D004008:Diclofenac; D005557:Formaldehyde; D009020:Morphine; D019342:Acetic Acid; D002211:Capsaicin; D000077239:Meloxicam