Non-steroidal anti-inflammatory drugs with different cyclooxygenase inhibitory profiles that prevent aberrant crypt foci formation but vary in acute gastrotoxicity in a rat model

Background: Standard non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer; however, their use as preventive agents is limited by their inherent toxicity. Drugs that selectively inhibit cyclooxygenase-2 (COX-2) may be useful in this setting as they are supposedly less toxic. No study has directly compared the ability of standard NSAIDs and selective COX-2 inhibitors to inhibit colorectal cancer at clinically relevant doses. Methods: Aberrant crypt foci (ACF) were induced in Sprague-Dawley rats by using 1,2-dimethylhydrazine (DMH). Test agents or vehicle were then administered for 3 weeks, twice daily through orogastric garage. At the end of this period, the number and multiplicity of ACF were determined. The agents tested at equivalent anti-inflammatory doses were: Sulindac and indomethacin (standard NSAIDs), meloxicam (selective COX-2 inhibitor), celecoxib (specific COX-2 inhibitor) and sulindac sulfone (no known COX activity). Acute gastrotoxicity of NSAID in rats was compared by using quantitative histology. Results: All test agents reduced the number of ACF. There was a 42% reduction with indomethacin, 46% with sulindac, 46% with meloxicam, 22% with celecoxib and 36% with sulindac sulfone. Only the COX-2 inhibitors caused no significant gastrotoxicity in rats. Conclusions: Cyclooxygenase-2 inhibitors are potentially ideal chemopreventive agents as they inhibit ACF and are not gastrotoxic.