Comparison of indomethacin and nimesulide, a selective cyclooxygenase-2 inhibitor, on key pathophysiologic steps in the pathogenesis of nonsteroidal anti-inflammatory drug enteropathy in the rat.
BACKGROUND
The predicted gastrointestinal tolerability of specific cyclooxygenase-2 inhibitors could be due to either a lack of 'topical' irritation and/or lack of effect on cyclooxygenase-1.


METHODS
Key pathophysiologic steps (in vitro and in vivo uncoupling, intestinal prostanoid levels (prostaglandin E, thromboxane B2, and 6-keto-prostaglandin F1alpha), intestinal permeability (51Cr-ethylenediaminetetraacetic acid), inflammation (faecal excretion of a granulocyte marker protein), and ulcer counts) in enteropathy induced by nonsteroidal anti-inflammatory drugs were assessed after administration of indomethacin, 10 mg/kg, and 15 (roughly equipotent), 30, and 60 mg/kg of the preferential cyclooxygenase-2 inhibitor nimesulide.


RESULTS
Indomethacin uncoupled oxidative phosphorylation at lower concentrations than nimesulide in vitro. Indomethacin was associated with electron microscopy changes suggestive of uncoupling in 60%-70% of enterocytes examined, whereas nimesulide affected 10%-30% of enterocytes, depending on the dose. Indomethacin increased intestinal permeability and caused inflammation and ulcers with 71%-96% reductions in prostanoid levels. Nimesulide at 15 mg/kg caused no damage, whereas 30 and 60 mg/kg nimesulide were associated with significant decreases in mucosal prostanoids (46%-75%), but only the 60-mg/kg dose caused a transient increase in intestinal permeability. However, at none of the doses did nimesulide cause intestinal inflammation or ulcers.


CONCLUSIONS
These results endorse the idea that selective cyclooxygenase-2 inhibitors may be associated with some gastrointestinal tolerance due to their selectivity for cyclooxygenase-2, inhibiting cyclooxygenase-1 at only very high doses, and reduced topical irritation.
Sigthorsson
G
G
Dept. of Medicine and Clinical Biochemistry, King's College School of Medicine and Dentistry, London, UK.
Jacob
M
M
Wrigglesworth
J
J
Somasundaram
S
S
Tavares
I
I
Foster
R
R
Roseth
A
A
Rafi
S
S
Mahmud
T
T
Simpson
R
R
Bjarnason
I
I
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000633:toxicity*; D002463:Cell Membrane Permeability / Q000187:drug effects; D016861:Cyclooxygenase Inhibitors / Q000633:toxicity*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000737:chemistry; D007213:Indomethacin / Q000633:toxicity*; D007410:Intestinal Diseases / Q000139:chemically induced* / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D008928:Mitochondria / Q000187:drug effects / Q000648:ultrastructure; D010101:Oxygen Consumption / Q000187:drug effects; D011453:Prostaglandins / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D018709:Statistics, Nonparametric; D013449:Sulfonamides / Q000633:toxicity*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016861:Cyclooxygenase Inhibitors; D011453:Prostaglandins; D013449:Sulfonamides; C012655:nimesulide; D007213:Indomethacin