Comparative study of anti-inflammatory and ulcerogenic activities of different cyclo-oxygenase inhibitors

Physiologically based pharmacokinetic (PBPK) modeling of meloxicam in different CYP2C9 genotypes

Meloxicam, a non-steroidal anti-inflammatory drug, is used for the treatment of rheumatoid arthritis and osteoarthritis. Cytochrome P450 (CYP) 2C9 and CYP3A4 are major and minor enzymes involved in the metabolism of meloxicam. Impaired enzyme activity of CYP2C9 variants increases the plasma exposures of meloxicam and the risk of adverse events. The objective of our study is to develop and validate the physiologically based pharmacokinetic (PBPK) model of meloxicam related to CYP2C9 genetic polymorphism using the PK-Sim^® software. In vitro k_cat of CYP2C9 was optimized in different CYP2C9 genotypes. The demographic and pharmacokinetic dataset for the development of the PBPK model was extracted from two previous clinical pharmacokinetic studies. Thirty-one clinical datasets, representing different dose regimens and demographic characteristics, were utilized to validate the PBPK model. The shapes of simulated plasma concentration-time profiles in each CYP2C9 genotype were visually similar to observed profiles. The predicted exposures (AUC_inf) of meloxicam in CYP2C9*1/*3, CYP2C9*1/*13, and CYP2C9*3/*3 genotypes were increased by 1.77-, 2.91-, and 8.35-fold compared to CYP2C9*1/*1 genotype, respectively. In all datasets for the development and validations, fold errors between predicted and observed pharmacokinetic parameters were within the two-fold error criteria. As a result, the PBPK model was appropriately established and properly described the pharmacokinetics of meloxicam in different CYP2C9 genotypes. This study is expected to contribute to reducing the risk of adverse events of meloxicam through optimization of meloxicam dosing in different CYP2C9 genotypes.

ADMINISTRATION OF H2 BLOCKERS IN NSAID INDUCED GASTROPATHY IN RATS: effect on histopathological changes in gastric, hepatic and renal tissues

ABSTRACT Background Nonsteroidal anti-inflammatory drugs induces gastric mucosal lesions because of its acidic properties. Ranitidine, an H2 receptor antagonist, has proved beneficial in patients with gastric ulcers. Objective The present study was performed to assess the effect of administering ranitidine in Nonsteroidal anti-inflammatory drugs (diclofenac, nimesulide) induced gastropathy, and their effect on the histopathology of stomach, kidney and liver. Methods Diclofenac, nimesulide, and ranitidine were administered in doses of 2, 4, and 6 mg/kg, p.o. once daily for 14 days, and their effect on gastric volume, acidity, mean ulcer number, and gastric pH. In addition, histopathological examination was also performed on sections of stomach, kidney and liver. Results Following the administration of diclofenac or nimesulide, all the gastric parameters were significantly altered as well as the histopathology of stomach, liver and kidney. In the control group, the renal sections showed normal glomeruli with no thickening of glomerular basement membrane, while in diclofenac alone, nimesulide alone, and ranitidine with nimesulide groups, the thickening of glomerular basement membrane was observed. These alterations were observed to be reversed in the ranitidine with diclofenac group. In the sections from the liver, the control group showed anastomosing plates and cords of cuboidal hepatocytes with round well stained nuclei and abundant cytoplasm. In the ranitidine with diclofenac, and ranitidine with nimesulide groups, mild dilatation of sinusoids is seen coupled with prominence of central vein. In the diclofenac alone and nimesulide alone groups, the proximal and distal convoluted tubules show mild focal tubular necrosis. In the gastric sections, the control group showed several folds forming villi, and the epithelial lining surface of the mucosa. In the ranitidine with diclofenac, and ranitidine with nimesulide groups, the duodenum showed scattered inflammatory cells composed predominantly of lymphocytes. In diclofenac alone and nimesulide alone group, the sections from the gastric areas showed partial necrosis and mild chronic inflammation respectively. Conclusion The study, therefore, has provided therapeutic rationale towards simultaneous administration of H2 receptor blocker ranitidine with diclofenac to be more beneficial as compared to ranitidine with nimesulide, to minimise the gastric intolerance of diclofenac in long term treatment of inflammatory conditions.

Effects of nonsteroidal anti-inflammatory meloxicam on stomach, kidney, and liver of rats

Nonsteroidal anti-inflammatory (NSAI) drugs are the most commonly used group of drugs today. Increase in the use of standard NSAI for treating pain and inflammation was restricted by the fact that these drugs were proven to possibly cause gastrointestinal and renal toxicity. Meloxicam is a NSAI that has anti-inflammatory, analgesic, and antipyretic effects. This study aims to investigate the effects of meloxicam on stomach, kidney, and liver of rats under light microscopy level. Based on the light microscopic observations, mononuclear cell infiltration and pseudolobular formation was established in liver samples of animals in the experimental group. Metaplasia in surface and glandular epithelia and atrophy were observed in stomach samples. Glomerular stasis-related hypertrophy and focal interstitial nephritis were found in kidneys. It was concluded in this study that meloxicam might cause hepatotoxicity, nephrotoxicity, and gastric metaplasia in rats at a used dose and duration.

An overview of clinical pharmacology of Ibuprofen

Ibuprofen was the first member of Propionic acid derivatives introduced in 1969. It is a popular domestic and over the counter analgesic and antipyretic for adults and children. Ibuprofen has been rated as the safest conventional NSAID by spontaneous adverse drug reaction reporting systems in the UK. This article summarizes the main pharmacological effects, therapeutical applications and adverse drug reactions, drug-drug interactions and food drug interactions of ibuprofen that have been reported especially during the last 10 years.

Prophylactic use of NSAIDs by athletes: a risk/benefit assessment

Athletes often seek artificial means to gain advantage and prolong participation when competing. This often involves taking naturally occurring or chemically synthesized compounds. The World Anti-Doping Agency does not prohibit the use of nonsteroidal anti-inflammatory drugs (NSAIDs) because these agents are not performance enhancing, and their analgesic and anti-inflammatory effects are at best performance enabling. Consequently, athletes have relatively unrestricted access to NSAIDs, which are readily available as over-the-counter drugs. However, concern has been raised on athletes' prophylactic use of these agents. Data from many sporting fields have consistently demonstrated that many individuals self-administer NSAIDs prior to athletic participation to prevent pain and inflammation before it occurs. However, scientific evidence for this approach is currently lacking, and athletes should be aware of the potential risks in using NSAIDs as a prophylactic agent. These agents are not benign, and can produce significant side effects, including gastrointestinal and cardiovascular conditions, as well as musculoskeletal and renal side effects. The latter side effects appear paradoxical to the rationale for prophylactic use of NSAIDs. This article discusses current observations regarding athlete use of NSAIDs, and the possible benefits and potential risks of their use.

Synergistic interaction between meloxicam and aminoguanidine in formalin-induced nociception in mice

OBJECTIVES

The objective of this study was to examine the nature of interaction between cyclooxygenase-2 inhibitor meloxicam and inducible nitric oxide synthase inhibitor aminoguanidine in formalin-induced nociception in mice and the possible therapeutic advantage.

METHODS

Antinociceptive effect of meloxicam (1, 3, 10 and 30 mg/kg, oral) and aminoguanidine (10, 30, 100 and 300 mg/kg, oral) and their combinations was examined in formalin-induced paw licking model in mice. Analysis of variance and isobolographic method were employed to identify the nature of antinociceptive interaction.

RESULTS

Higher doses of meloxicam (10 and 30 mg/kg) and aminoguanidine (100 and 300 mg/kg) produced significant reduction in paw licking time (antinociceptive) in late phase of formalin-induced nociception. Combination of sub-threshold dose of meloxicam (3 mg/kg) with increasing doses of aminoguanidine (10, 30, 100 and 300 mg/kg) resulted in synergistic antinociceptive effect. Similarly, co-administration of sub-threshold dose of aminoguanidine (30 mg/kg) with increasing doses of meloxicam (1, 3, 10 and 30 mg/kg) produced significant reduction in formalin-induced paw licking behaviour. The experimental ED(50) for combination with their confidence limits are below the confidence interval of theoretical line of additive interaction, suggesting synergistic nature of interaction between meloxicam and aminoguanidine in isobolographic analysis.

CONCLUSION

Co-administration of meloxicam and aminoguanidine showed synergistic antinociceptive effect which might possibly reduce gastrointestinal toxicity associated with the use of meloxicam.

Effect of different cyclooxygenase inhibitors on gastric adaptive cytoprotection induced by 20% ethanol

In this study, we evaluated the effect of two different dosages of therapeutically prescribed nonsteroidal anti-inflammatory drugs (NSAIDs), ibuprofen, diclofenac, nimesulide, meloxicam, and celecoxib (ED80 for COX-1 and COX-2) on normal gastric mucosa and mucosa, previously exposed to 20% ethanol. At COX-2-inhibiting dosages, the NSAIDs tested were nonulcerogenic, and the same response profile was observed in "adapted" stomachs. Interestingly, low doses of nimesulide and celecoxib increase the levels of Prostaglandin E(2) and COX-2, and protect against subsequent 100% ethanol exposition, suggesting that these drugs may act as "mild irritants" to gastric mucosa. The ulcerogenic response to NSAIDs was prevented by the previous 20% ethanol exposition, probably the result of nitric oxide synthesis, because PGE(2) levels in gastric mucosa were reduced by these agents and a concomitant nitric oxide blockade reversed this protection.