Gastro-duodenal protection in an era of cyclo-oxygenase-2-selective nonsteroidal anti-inflammatory drugs

The effects of drug transporters on the efficacy of methotrexate in the treatment of rheumatoid arthritis

The ATP-binding cassette (ABC) and solute carrier (SLC) transporter families consist of common drug transporters that mediate the efflux and uptake of drugs, respectively, and play an important role in the absorption, distribution, metabolism and excretion of drugs in vivo. Rheumatoid arthritis (RA) is an autoimmune disease characterized by erosive arthritis, and there are many RA patients worldwide. Methotrexate (MTX), the first-choice treatment for RA, can reduce the level of inflammation, prevent joint erosion and functional damage, and greatly reduce pain in RA patients. However, many patients show resistance to MTX, greatly affecting the efficacy of MTX. Many factors, such as irrational drug use and heredity, are associated with drug resistance. Considering the effect of drug transporters on drugs, many studies have compared the expression of drug transporters in drug-resistant and drug-sensitive patients, and abnormal transporter expression and transport activity have been found in patients with MTX resistance. Thus, drug transporters are involved in drug resistance. This article reviews the effects of transporters on the efficacy of MTX in the treatment of RA.

In vivo effects of amtolmetin guacyl on lipid peroxidation and antioxidant defence systems. Comparison with non-selective and COX-2 selective NSAIDs

1. The in vivo effects of the non-steroid anti-inflammatory drug (NSAID) amtolmetin guacyl, a pro-drug of the NSAID tolmetin, on lipid peroxidation, glutathione levels and activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase) in rat gastric mucosa, colon mucosa and liver, were compared with the effects of non-selective (indomethacin, diclofenac) and COX-2 selective (celecoxib) NSAIDs. 2. Indomethacin treatment led to an increase in lipid peroxidation, glutathione peroxidase and glucose-6-phosphate dehydrogenase activities and to a decrease in catalase activity and glutathione levels in gastric mucosa. In contrast, amtolmetin guacyl treatment was without effects in gastric and colon mucosa, or liver from control animals. Like amtolmetin guacyl, celecoxib had no effect on the lipid peroxidation, or on enzyme and non-enzyme antioxidant defence systems in gastric mucosa. 3. It is suggested that the lack of pro-oxidant effects in vivo associated with amtolmetin guacyl treatment contribute improved gastric tolerability.

Prevention of ulcers by esomeprazole in at-risk patients using non-selective NSAIDs and COX-2 inhibitors

OBJECTIVES

Proton pump inhibitors reduce ulcer recurrence in non-steroidal anti-inflammatory drug (NSAID) users, but their impact in at-risk ulcer-free patients using the current spectrum of prescribed agents has not been clearly defined. We assessed esomeprazole for ulcer prevention in at-risk patients (> or = 60 yr and/or ulcer history) taking NSAIDs, including COX-2 inhibitors. Such studies are particularly relevant, given that concerns regarding adverse cardiovascular outcomes among COX-2 inhibitor users may prompt re-evaluation of their use.

METHODS

We conducted two similar double-blind, placebo-controlled, randomized, multicenter studies; VENUS (United States) and PLUTO (multinational). A total of 844 and 585 patients requiring daily NSAIDs, including COX-2 inhibitors were randomized to receive esomeprazole (20 or 40 mg) or placebo, daily for 6 months.

RESULTS

In the VENUS study, the life table estimated proportion of patients who developed ulcers over 6 months (primary variable, intent-to-treat population) was 20.4% on placebo, 5.3% on esomeprazole 20 mg (p < 0.001), and 4.7% on esomeprazole 40 mg (p < 0.0001). In the PLUTO study, the values were 12.3% on placebo, 5.2% with esomeprazole 20 mg (p = 0.018), and 4.4% with esomeprazole 40 mg (p = 0.007). Significant reductions were observed for users of both non-selective NSAIDs and COX-2 inhibitors. Pooled ulcer rates for patients using COX-2 inhibitors (n = 400) were 16.5% on placebo, 0.9% on esomeprazole 20 mg (p < 0.001) and 4.1% on esomeprazole 40 mg (p= 0.002). Esomeprazole was well tolerated and associated with better symptom control than placebo.

CONCLUSIONS

For at-risk patients, esomeprazole was effective in preventing ulcers in long-term users of NSAIDs, including COX-2 inhibitors.

Predicting the risk for gastrointestinal toxicity in patients taking NSAIDs: the Gastrointestinal Toxicity Survey

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most widely used drugs in the world, but their use is often associated with adverse gastrointestinal (GI) events that may be life threatening in some patients. Development of simple questionnaires for predicting GI events in individuals taking NSAIDs may help to prevent use of these drugs in high-risk patients. The present study was undertaken to test a new questionnaire designed to identify patients at high risk for NSAID-associated GI events--the Gastrointestinal Toxicity Survey (NSAID Induced) (GITS [NI]). In this study, results for GITS (NI) were compared with those for an established questionnaire, the Stanford Calculator of Risk for Events (SCORE), in a small cohort of 400 patients. Feasible generalized least squares (FGLS) and multinomial logistic (MNL) regression were used to perform the comparison. The overall correlation between results for GITS (NI) responses and the total score for the SCORE questionnaire was 0.962 (P < .0001). The agreement between the 2 instruments with respect to their ability to predict the same risk for NSAID-induced GI events was similar for both FGLS and MNL. For 4 levels of risk, the agreement was approximately 80% between the 2 instruments. For 3 levels of risk, the agreement was approximately 90%. This study showed that results obtained with GITS (NI) are highly correlated with those from SCORE and that GITS (NI) may provide physicians with information that will help them avoid administering NSAIDs to patients who are at high risk for adverse GI reactions.

Rofecoxib: an update on physicochemical, pharmaceutical, pharmacodynamic and pharmacokinetic aspects

Rofecoxib (MK-966) is a new generation non-steroidal anti-inflammatory agent (NSAID) that exhibits promising anti-inflammatory, analgesic and antipyretic activity. It selectively inhibits cyclooxygenase (COX)-2 isoenzyme in a dose-dependent manner in man. No significant inhibition of COX-1 is observed with rofecoxib up to doses of 1000 mg. The pharmacokinetics of rofecoxib has been found to be complex and variable. Mean oral bioavailability after single dose of rofecoxib (12.5, 25 or 50 mg) is 93% with t(max) varying widely between 2 and 9 h. It is highly plasma-protein bound and is metabolized primarily by cytosolic reductases to inactive metabolites. Rofecoxib is eliminated predominantly by hepatic metabolism with a terminal half-life of approximately 17 h during steady state. Various experimental models and clinical studies have demonstrated rofecoxib to be superior, or at least equivalent, in anti-inflammatory, analgesic and antipyretic efficacy to comparator nonselective NSAIDs in osteoarthritis, rheumatoid arthritis and other pain models. Emerging evidence suggests that rofecoxib may also find potential use as supportive therapy in various pathophysiologic conditions like Alzheimer's disease, and in various malignant tumours and polyps, where COX-2 is overly expressed. Rofecoxib is generally well-tolerated. Analysis of data pooled from several trials suggests that rofecoxib is associated with fewer incidences of clinically symptomatic gastrointestinal ulcers and ulcer complications vis-à-vis conventional NSAIDs. However, this gastropreserving effect may be negated by concurrent use of low-dose aspirin for cardiovascular risk reduction. Rofecoxib tends to show similar tolerability for renal and cardiothrombotic events as compared with nonnaproxen nonselective NSAIDs. No clinically significant drug interaction has been reported for rofecoxib except with diuretics, where it reverses their salt-wasting effect and thus can be clinically exploited in electrolyte-wasting disorders. There is only modest information about the physicochemical and pharmaceutical aspects of rofecoxib. Being poorly water soluble, its drug delivery has been improved using varied formulation approaches. Although it is stable in solid state, rofecoxib is photosensitive and base-sensitive in solution form with its degradation mechanistics elucidated. Analytical determinations of rofecoxib and its metabolites in biological fluids employing HPLC with varied types of detectors have been reported. Isolated studies have also been published on the chromatographic and spectrophotometric assay of rofecoxib and its degradants in bulk samples and pharmaceutical dosage forms. The current article provides an updated overview on the physicochemical, pharmaceutical, pharmacokinetic and pharmacodynamic vistas of rofecoxib.