mobic and Pleurisy

We studied the effects of meloxicam on prostanoid levels, both in the inflammatory site in rat carrageenin-induced pleurisy and in the rat stomach injected with 1 mol/l NaCl solution, to clarify the relationship between its low gastric toxicity and its relative cyclooxygenase (COX) 2 selectivity. NS-398 (3 mg/kg), a highly selective COX-2 inhibitor, and meloxicam (3 mg/kg) exhibited anti-inflammatory effects in the pleurisy model. Prostaglandin (PG) E(2) thromboxane (TX) B(2) and 6-keto-PGF(1alpha) were detectable in the inflammatory site. Anti-inflammatory doses of NS-398 and meloxicam each suppressed the intrapleural PGE(2) level at 5 h as potently as piroxicam (3 mg/kg) as aspirin (100 mg/kg), both of which are nonselective COX inhibitors. NS-398 was much less potent than the other three in suppressing the levels of TXB(2) and 6-keto-PGF(1alpha). These results suggest that PGE(2) may be produced mainly via COX-2 in this model and that meloxicam may inhibit COX-2 in the inflammatory site. Piroxicam completely inhibited the increase in gastric PGE(2) induced by administering 1 mol/l NaCl solution into the rat stomach. Nimesulide (3 mg/kg), another selective COX-2 inhibitor, however, never affected this increase, suggesting that the gastric PGE(2) may be produced via COX-1. The anti-inflammatory dose of meloxicam caused statistically nonsignificant suppression of the PGE(2) level, by approximately 50%. These results suggest that the potent anti-inflammatory effect of meloxicam, accompanied with low gastric toxicity, may be related to its relative selectivity for COX-2 over COX-1.

Topics: 6-Ketoprostaglandin F1 alpha; Animals; Anti-Inflammatory Agents, Non-Steroidal; Carrageenan; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dinoprostone; Gastric Juice; Isoenzymes; Male; Meloxicam; Membrane Proteins; Nitrobenzenes; Pleura; Pleurisy; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Stomach; Sulfonamides; Thiazines; Thiazoles

We studied the anti-inflammatory activity of meloxicam on rat carrageenin-induced pleurisy and its toxicity for rat gastric mucosa, relative to its in vitro inhibitory potency against partially purified cyclooxygenase (COX)-1 and COX-2 preparations in order to clarify the pharmacological profile of the compound as an anti-inflammatory agent. In rat carrageenin-induced pleurisy, the plasma exudation rate peaked at 5 h, at which time COX-2 was detectable in cells from the pleural exudate. Meloxicam and piroxicam (1 and 3 mg/kg) and NS-398 (3 mg/kg) showed almost equal anti-inflammatory potency against 5-hour pleurisy. A single oral administration of the compounds caused a dose-dependent increase in the number of rats with gastric mucosal erosion. The ED50 value for meloxicam (5.92 mg/kg) was significantly higher than that for piroxicam (1.76 mg/kg), indicating that meloxicam is safer. Indometacin showed intermediate safety (2.59 mg/kg). In in vitro experiments, indometacin inhibited COX-1 about 1.7 times more potently than COX-2. NS-398 inhibited COX-2 with an IC50 of 0.32 microM, but never affected COX-1 activity, even at 100 microM. In the same assay system, meloxicam inhibited COX-2 about 12 times more selectively than COX-1. Piroxicam, however, inhibited both isoforms almost equally. These results indicate that meloxicam is a potent anti-inflammatory agent with low gastric toxicity. One reason for its in vivo pharmacological profile may be related to its relative selectivity for COX-2 over COX-1. Thus, meloxicam may belong to a group of COX-2 selective anti-inflammatory agents with a better safety profile than conventional COX-1 and COX-2 nonselective anti-inflammatory agents.

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents, Non-Steroidal; Carrageenan; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Dose-Response Relationship, Drug; Gastric Mucosa; In Vitro Techniques; Indomethacin; Isoenzymes; Male; Meloxicam; Membrane Proteins; Nitrobenzenes; Piroxicam; Pleurisy; Prostaglandin-Endoperoxide Synthases; Rats; Rats, Wistar; Sulfonamides; Therapeutic Equivalency; Thiazines; Thiazoles

Meloxicam is a new nonsteroidal anti-inflammatory drug (NSAID) derived from enolic acid. Preclinical studies have indicated that meloxicam has potent anti-inflammatory activity, together with a good gastrointestinal and renal tolerability profile. This report summarizes studies undertaken to compare meloxicam to other NSAIDs in the inhibition of the inducible cyclooxygenase (COX-2) in inflamed areas (pleurisy of the rat, peritonitis of mice) and their influence on the activity of the constitutive cyclooxygenase (COX-1) in stomach, kidney, brain, and blood. In pleurisy of the rat, meloxicam was twice as potent as tenoxicam, 3 times as potent as flurbiprofen, 8 times as potent as diclofenac, and 20 times as potent as tenidap at inhibiting prostaglandin E2 (PGE2) biosynthesis. In the peritonitis model in mice, meloxicam was approximately twice as active as piroxicam, and more than 10 times as active as diclofenac in the suppression of PGE biosynthesis. Doses of meloxicam sufficient to inhibit PGE2 biosynthesis in the pleural exudate and peritoneal exudate had no influence on leukotriene-B4 (LTB4) or leukotriene-C4 (LTC4) content. The effect of meloxicam on the PGE2 content of rat gastric juice and rat urine was weaker than that of piroxicam or diclofenac. Meloxicam was a weaker inhibitor of the increased PGE2 concentration in brain of rats and mice (induced by convulsant doses of pentetrazole) than piroxicam, diclofenac, or indomethacin. Meloxicam had a weaker effect on serum thromboxane-B2 (TXB2) concentration in rats than piroxicam or tenoxicam. The in vivo findings confirm the results of in vitro tests, conducted separately, showing that meloxicam preferentially inhibits COX-2 over COX-1. COX-2 is the inducible isoenzyme implicated in the inflammatory response, whereas COX-1 has cytoprotective effects in the gastric mucosa. Therefore, a preferential selectivity for one isoenzyme over another, as displayed by meloxicam, may have implications in the clinical setting in terms of a more favorable risk: benefit profile.

Topics: Administration, Oral; Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acid; Brain; Convulsants; Cyclooxygenase Inhibitors; Dinoprostone; Female; Gastric Juice; Inflammation; Isoenzymes; Kidney; Leukotriene B4; Male; Meloxicam; Mice; Pentylenetetrazole; Pleurisy; Rats; Stomach; Thiazines; Thiazoles