In vivo effects of amtolmetin guacyl on lipid peroxidation and antioxidant defence systems in different models of gastrointestinal injury

Amtolmetin: A Reappraisal of NSAID with Gastroprotection

Aim. To assess the gastrosparing effect of amtolmetin guacyl (AMG) against other nonsteroidal anti-inflammatory drugs (NSAIDs) in patients with osteo-/rheumatoid arthritis. Methods. A literature search was done in the electronic databases (PubMed, Google Scholar, Embase, and Scopus) with key words “amtolmetin guacyl”, “amtolmetin”, and “arthritis”; filters were applied to obtain publications between 01-Jan-1985 and 01-Oct-2015, which were “clinical trials” in osteo-/rheumatoid arthritis patients and in “English language.” Studies were assessed using the Jadad criteria and trials with score ≥ 3 were included in the analysis to compare the safety and efficacy of AMG against other NSAIDs. Results. Search yielded 19 publications of which 3 were included for analysis. Baseline characteristics of patients were comparable between the AMG group and other NSAIDs (diclofenac, celecoxib, and piroxicam) groups in all trials. Efficacy of AMG was similar to the other NSAIDs compared in the trials. The number of adverse events (AEs) reported was similar between both the groups; however, severe AEs reported were significantly lower in the AMG group. Of note was the significant lower number of duodenal ulcers after treatment in the AMG group. Conclusions. AMG has efficacy similar to other NSAIDs and a safer gastrointestinal AE profile when compared to the other NSAIDs.

Mechanism of action of celecoxib on normal and acid-challenged gastric mucosa

Selective COX-2 inhibitor, celecoxib, delays the healing of gastric ulcers by inhibiting prostaglandins synthesis. Therefore, the effect of celecoxib on normal and acid-challenged gastric mucosa was studied. Wistar rats were distributed into four groups: group-1 (vehicle treated), group-2 (celecoxib treated), group-3 (given 0.6N HCl) and group-4 (HCl+celecoxib treated). The gastric mucosa was assessed histopathologically and by evaluating gastric adherent mucus. To assess the role of oxidative stress, the levels of free radicals and antioxidants were measured. The histopathological examination showed mild inflammation in group-2, moderate inflammation in group-3 and severe inflammation in group-4. The results showed an increase in malondialdehyde and a decrease in gastric adherent mucus, nitrite, reactive thiols and glutathione in groups-2-4 as compared to control group. Activity of superoxide dismutase, catalase and glutathione-s-transferase was increased in all the groups except the group-1. The present study suggested that celecoxib aggravated the gastric damage caused by acid which may be mediated by altering the balance between free radicals and antioxidants.

Potential antioxidant activity of celecoxib and amtolmetin guacyl: in vitro studies

1. In vitro studies of the potential antioxidant activity of the selective cyclo-oxygenase-2 inhibitor celecoxib and the non-steroid anti-inflammatory drug amtolmetin guacyl (AMG) were carried out. The study included experiments on the ability of these drugs to affect some indices of the oxidative stress [lipid peroxidation (LP), activity of antioxidant enzymes, glutathione (GSH) level] in rat stomach and colon mucosa and in liver. 2. Celecoxib and AMG did not change the activity of the enzymes GSH-peroxidase, oxidased glutathione (GSSG)-reductase and glucose-6-phosphate-dehydrogenase, as well as the GSH level in all tissue preparations. An increased superoxide dismutase (SOD) activity and a tendency to a decreased Fe/ascorbic acid-induced LP in stomach and colon mucosa were found, but only in the presence of AMG. 3. In the liver, both celecoxib and AMG decreased spontaneous and Fe/ascorbic acid-induced LP. SOD activity was enhanced only in the presence of AMG. 4. Experiments aimed at studying celecoxib and AMG in free oxygen radical-generating systems were also carried out. AMG and tolmetin (the main metabolite of AMG) inhibited OH*-provoked deoxyribose degradation in a Fenton system. Celecoxib had no effect on free radicals when tested in the same system. 5. In conclusion, the results of the present in vitro studies suggest that AMG and celecoxib possess antioxidant and metal-chelating abilities, which might contribute to their beneficial effects.