The primary endpoint of this study was to compare the renal tolerability of amtolmetin guacyl (AMG), diclofenac and rofecoxib in elderly patients with symptomatic osteoarthritis (OA). The assessment of efficacy was the secondary endpoint.
90 patients who satisfied the American College of Rheumatology classification criteria for hand, hip or knee OA were randomly assigned to 3 treatment groups receiving either: AMG 1,200 mg over thefirst 3 days and and 600 mg/day thereafter; diclofenac 150 mg/day; or rofecoxib 25 mg/day for 2 weeks. At baseline and after therapy patients were clinically assessed by the same examiner who was unaware of the treatment arm assignement. Serum and urinary parameters of renal function and the outcome measures of efficacy were evaluated before (t(0)) and after therapy (t(1)).
Diclofenac produced a significant reduction in creatinine clearance (t(0) = 88.93 +/- 11.59; t(1) = 75.90 +/- 16.32; p: < 0.001) and in the daily urine volume (t(0) = 1,337.93 +/- 202.07; t(1) = 1,027.59 +/- 249.14; p: < 0.001). In the same treatment group a significant increase in serum creatinine, blood urea nitrogen, uric acid and potassium were observed. Rofecoxib treated patients showed a significant increase in body weight (t(0) = 75.31 +/- 4.26; t(1) = 76.54 +/- 4.84; p: < 0.001), systolic blood pressure (t(0) = 144 +/- 10.86; t(1) = 154 +/- 11.8; p < 0.001), diastolic blood pressure (t(0) = 80 +/- 6.05; t(1) = 89 +/- 7.66; p < 0.001) and serum sodium (t(0) = 138.73 +/- 1.28; t(1) = 140.12 +/- 1.80; p < 0.005) associated with a significant decrease in the daily urine volume (t(0) = 1294.64 +/- 205.21; t, = 1,115.48 +/- 238.47; p < 0.001) and creatinine clearance (t(0)= 86.73 +/- 8.14; t(1) = 83.15 +/- 7.96; p < 0.01). No significant changes in the clinical and humoral parameters were recorded in AMG treated patients. Diclofenac was more efficacious than the other 2 drugs (p < 0.001). No differences were observed between AMG and rofecoxib. Side effects related to altered kidney function were significantly higher in the rofecoxib group (p < 0.005).
Diclofenac mainly impaired blood renal flow and the glomerularfiltration rate, while rofecoxib negatively influenced the renal sodium-water exchange. AMG demonstrated a renal sparing effect, although the eract mechanism is unclear