Etodolac, a new nonsteroidal anti-inflammatory drug: gastrointestinal microbleeding and endoscopic studies

Cyclooxygenase Isozymes: The Biology of Prostaglandin Synthesis and Inhibition

Nonsteroidal anti-inflammatory drugs (NSAIDs) represent one of the most highly utilized classes of pharmaceutical agents in medicine. All NSAIDs act through inhibiting prostaglandin synthesis, a catalytic activity possessed by two distinct cyclooxygenase (COX) isozymes encoded by separate genes. The discovery of COX-2 launched a new era in NSAID pharmacology, resulting in the synthesis, marketing, and widespread use of COX-2 selective drugs. These pharmaceutical agents have quickly become established as important therapeutic medications with potentially fewer side effects than traditional NSAIDs. Additionally, characterization of the two COX isozymes is allowing the discrimination of the roles each play in physiological processes such as homeostatic maintenance of the gastrointestinal tract, renal function, blood clotting, embryonic implantation, parturition, pain, and fever. Of particular importance has been the investigation of COX-1 and -2 isozymic functions in cancer, dysregulation of inflammation, and Alzheimer's disease. More recently, additional heterogeneity in COX-related proteins has been described, with the finding of variants of COX-1 and COX-2 enzymes. These variants may function in tissue-specific physiological and pathophysiological processes and may represent important new targets for drug therapy.

Complementary studies of the gastrointestinal safety of the cyclo-oxygenase-2-selective inhibitor etoricoxib

BACKGROUND

Cyclo-oxygenase-2-selective non-steroidal anti-inflammatory drugs are intended to preserve cyclo-oxygenase-1-mediated gastroprotection and platelet function, whilst inhibiting cyclo-oxygenase-2-mediated inflammation.

AIM

To assess the gastrointestinal safety of the cyclo-oxygenase-2-selective inhibitor etoricoxib vs. non-selective non-steroidal anti-inflammatory drugs.

METHODS

Two randomized, double-blind, placebo- and active-controlled studies were performed: (i) daily faecal red blood cell loss was measured in 62 subjects receiving etoricoxib (120 mg once daily), ibuprofen (800 mg t.d.s.) or placebo for 28 days; (ii) the incidence of endoscopically detectable gastric/duodenal ulcers was determined in 742 osteoarthritis or rheumatoid arthritis patients receiving etoricoxib (120 mg once daily), naproxen (500 mg b.d.) or placebo over 12 weeks.

RESULTS

In the first study, the between-treatment ratio of faecal blood loss for etoricoxib vs. placebo (1.06) was not significantly different from unity; however, the ratios for ibuprofen vs. placebo (3.26) and etoricoxib (3.08) were significantly greater than unity (P < 0.001). In the second study, the incidence of ulcers of > or = 3 mm with naproxen (25.3%) was significantly higher than that with etoricoxib (7.4%) or placebo (1.4%; P < 0.001); the results were similar for ulcers of > or = 5 mm.

CONCLUSIONS

The reduced toxicity of etoricoxib (less faecal blood loss and fewer endoscopically detectable lesions) suggests that use of this drug will may be associated with a reduced incidence of gastrointestinal perforations, ulcers and bleeds.

A randomized trial measuring fecal blood loss after treatment with rofecoxib, ibuprofen, or placebo in healthy subjects

PURPOSE

Gastrointestinal microbleeding, as assessed by the measurement of (51)chromium-labeled red blood cells, is a marker of the mucosal injury associated with the use of nonsteroidal anti-inflammatory drugs. This study tested the hypotheses that cyclooxygenase-2 specific inhibition with rofecoxib would cause less fecal blood loss than a therapeutic dose of ibuprofen and would be equivalent to placebo.

SUBJECTS AND METHODS

In this randomized, double-blind group study, gastrointestinal blood loss was assessed by measurement of fecal (51)chromium radioactivity during a 1-week placebo baseline period and during 4 weeks of treatment with rofecoxib (25 mg or 50 mg once daily), ibuprofen (800 mg three times daily), or placebo in 67 healthy subjects. Gastrointestinal blood loss during treatment weeks 2 to 4 (versus the baseline period) was expressed as the geometric mean ratio of fecal radioactivity in weeks 2 to 4 compared with baseline.

RESULTS

Ibuprofen caused significantly (P <0.001) greater gastrointestinal blood loss (geometric mean ratio of 5.2, 95% confidence interval [CI]: 4.2 to 6.3) than the 25-mg dose of rofecoxib (2.6, 95% CI: 2.2 to 3.1), the 50-mg dose of rofecoxib (2.6, 95% CI: 2.2 to 3.0), or placebo (2.1, 95% CI: 1.8 to 2.5). In contrast, gastrointestinal blood loss with both doses of rofecoxib were equivalent to placebo by a predetermined clinical similarity bound.

CONCLUSIONS

In healthy subjects, treatment with rofecoxib, at 2 to 4 times the doses that are currently recommended for the treatment of patients with osteoarthritis, produced significantly less fecal blood loss than a therapeutic dose of ibuprofen and was equivalent to placebo.

Meta-analysis of two double-blind comparative studies with the sustained-release form of etodolac in rheumatoid arthritis

A meta-analysis was done with the data from two studies that provided the first efficacy and safety results for the new sustained-release (SR) formulation of etodolac versus established nonsteroidal anti-inflammatory drugs in patients with rheumatoid arthritis (RA). The studies were 4-week, double-blind, multicenter, randomized, parallel-group comparisons of etodolac SR 600 mg (102 patients) with either diclofenac SR 100 mg (65 patients) or piroxicam 20 mg (35 patients). The data for etodolac SR were pooled and compared with the pooled data for the comparators. The primary efficacy assessments (weeks 2 and 4) were physician and patient overall evaluation of the patient's condition, number of painful/tender joints, and number of swollen joints. Patients met at least five of the American Rheumatism Association diagnostic criteria and were within Steinbrocker progression stage I, II, or III and functional class I, II, or III. The homogeneity of the treatment groups across studies and the changes from baseline between groups were tested using a Cochran-Mantel-Haenszel test and an analysis of variance including "study," "treatment," and "center within treatment" factors and their interaction. The efficacy analysis was based on the final assessment during therapy (last visit). The patients in the etodolac SR group were older than those in the comparators group (P = 0.032), and there were more patients over 65 years of age in the etodolac SR group than in the comparators group (31% versus 14%, respectively; P = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Double-blind comparison of etodolac SR and diclofenac SR in the treatment of patients with degenerative joint disease of the knee

An on-going multi-centre, double-blind, parallel-group study is being carried out to compare the efficacy and tolerability of sustained-release (SR) formulations of etodolac and diclofenac in patients with degenerative joint disease (osteoarthritis) of the knee. An interim analysis of the findings has been made for 64 patients from two centres which have now completed their part in the study. Thirty-two patients were randomly assigned to receive 600 mg etodolac SR once daily for 4 weeks; the remaining 32 patients received 100 mg diclofenac SR. Primary efficacy assessments rated on a 5-point categorical scale were patient and physician overall assessments of the patient's condition, night pain and pain intensity. Secondary efficacy parameters included weight-bearing pain, stiffness duration, joint tenderness on pressure, degree of swelling and erythema, degree of knee flexion and time to walk 15 metres. The results showed that for both etodolac SR and diclofenac SR treatment groups there was an improvement from baseline in all efficacy parameters at the last visit and no statistically significant difference was observed between treatments. However, although not statistically significant, the improvement rate in the patient's condition at Week 2 was slightly greater in the etodolac SR treatment group, suggesting that improvement may occur more rapidly with etodolac SR than with diclofenac SR. With regard to tolerability, 5 patients in the etodolac SR treatment group and 3 in the diclofenac SR group withdrew from the study because of adverse reactions. Two events (dyspepsia and mouth ulceration) in the etodolac SR group and 4 events (headache, glossitis, depression and insomnia) in the diclofenac SR group were considered to be definitely drug-related. Dyspepsia was reported by 3 patients (1 withdrawal) treated with etodolac SR and by 4 patients (2 withdrawals) treated with diclofenac SR. A statistically significant decrease was observed in haemoglobin and haematocrit values after 4 weeks of treatment in the diclofenac SR group, but this was not considered to be clinically important. In addition, there were no clinically significant changes in blood chemistry and urinalysis for either treatments. In conclusion, the results of the present study indicate that 600 mg etodolac SR once daily for 4 weeks is effective in the treatment of patients with degenerative joint disease of the knee, as is 100 mg diclofenac SR. In addition, both drugs have comparable tolerability profiles.

Double-blind, parallel comparison of etodolac and indomethacin in patients with osteoarthritis of the knee

The efficacy and tolerability of etodolac and indomethacin were compared in patients with osteoarthritis of the knee. Sixty-four patients entered a double-blind, parallel trial and were randomly assigned to receive 300 mg etodolac twice daily (n = 31) or 50 mg indomethacin 3-times daily (n = 33) for 6 weeks. Both groups showed significant (p less than or equal to 0.05) improvement from baseline in all efficacy assessments at the final evaluation. However, significantly (p less than or equal to 0.05) greater decreases from baseline were seen for etodolac than for indomethacin in patients' global evaluation, pain intensity, night pain, standing pain, walking pain, pain getting up from a chair, tenderness on pressure, and knee flexion. In addition, 67% of the patients in the etodolac group indicated improvement in their condition at the final evaluation, compared with 53% of the patients who received indomethacin. No patients in the etodolac group withdrew because of adverse reactions compared to 4 patients in the indomethacin group. Furthermore, significantly more patients in the indomethacin group (52%) than in the etodolac group (19%) reported drug-related adverse reactions. Thus, the results of this study strongly indicate that etodolac is more effective and produces fewer side-effects than indomethacin in the treatment of patients with osteoarthritis.

Double-blind comparison of etodolac and piroxicam in patients with rheumatoid arthritis

A study was carried out to compare the efficacy and tolerability of etodolac and piroxicam in patients with rheumatoid arthritis. Sixty patients entered this double-blind, parallel study and after a wash-out period of up to 2 weeks were randomly assigned to receive 200 mg etodolac twice daily or 20 mg piroxicam once daily for 12 weeks. Efficacy and tolerability assessments were made after 2, 4, 6, 8 and 12 weeks. Patients in the etodolac group demonstrated statistically significant improvement in the number of tender joints and the duration of morning stiffness after 12 weeks, as did the piroxicam-treated patients. In addition, the etodolac-treated patients had significant improvement according to the patients' and physician's global evaluations, pain intensity, number of swollen joints, and grip strength. There were significant differences between therapies favouring etodolac for the assessments of the number of tender joints and the physician's global evaluation by the end of the study. Forty-seven percent (47%) of 15 etodolac-treated patients compared with 7% of 15 piroxicam-treated patients showed improvement according to the physician's global evaluation at Week 12. Similarly, the patients' global evaluation showed that 40% of etodolac-treated patients and 19% of piroxicam-treated patients had improved by the end of therapy. Both therapies were well tolerated. There were no significant differences between groups in the incidence of any adverse reactions or the frequency of withdrawals.