title: Lack of effects of acemetacin on signalling pathways for leukocyte adherence may explain its gastrointestinal safety.
abstract: OBJECTIVE
  Acemetacin is a non-steroidal anti-inflammatory drug which is rapidly bioconverted to indomethacin, but produces significantly less gastric damage than indomethacin. This study was performed to investigate several possible mechanisms that could account for the gastrointestinal tolerability of acemetacin.
  
  
  METHODS
  The gastric and intestinal damaging effects of acemetacin and indomethacin were examined in the rat. Effects of the drugs on blood levels of leukotriene B(4) and thromboxane B(2), on leukocyte-endothelial adherence in post-capillary mesenteric venules, and on gastric expression of tumour necrosis factor-alpha (TNF-alpha) were determined. The two drugs were also compared for gastric toxicity in rats pretreated with inhibitors of COX-2 and NOS.
  
  
  RESULTS
  Acemetacin induced significantly less gastric and intestinal damage than indomethacin, despite markedly suppressing COX activity. Indomethacin, but not acemetacin, significantly increased leukocyte adherence within mesenteric venules, and gastric expression of TNF-alpha. Pretreatment with L-nitro-arginine methyl ester or lumiracoxib increased the severity of indomethacin-induced gastric damage, but this was not the case with acemetacin.
  
  
  CONCLUSIONS
  The increased gastric and intestinal tolerability of acemetacin may be related to the lack of induction of leukocyte-endothelial adherence. This may be attributable to the reduced ability of acemetacin to elevate leukotriene-B(4) synthesis and TNF-alpha expression, compared to indomethacin, despite the fact that acemetacin is rapidly bioconverted to indomethacin after its absorption.
authors.affiliation: Sección Externa de Farmacología, CINVESTAV/IPN, Mexico City, DF, Mexico.
authors.forename: A E
authors.initials: AE
authors.lastname: Chávez-Piña
authors.forename: L
authors.initials: L
authors.lastname: Vong
authors.forename: W
authors.initials: W
authors.lastname: McKnight
authors.forename: M
authors.initials: M
authors.lastname: Dicay
authors.forename: R C O
authors.initials: RC
authors.lastname: Zanardo
authors.forename: M I
authors.initials: MI
authors.lastname: Ortiz
authors.forename: G
authors.initials: G
authors.lastname: Castañeda-Hernández
authors.forename: J L
authors.initials: JL
authors.lastname: Wallace
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002448:Cell Adhesion / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005753:Gastric Mucosa / Q000378:metabolism*; D007213:Indomethacin / Q000031:analogs & derivatives* / Q000494:pharmacology; D007962:Leukocytes / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; C026784:acemetacin; D007213:Indomethacin