Comparative effects of long term treatment with etodolac, naproxen and ibuprofen on articular and bone changes associated with adjuvant arthritis in rats.

The effect of prolonged treatment with etodolac (8 mg/kg) on the articular and bone pathology at the tibiotarsal joint associated with adjuvant arthritis in the rat has been studied and compared to the effects produced by treatment with naproxen (8 mg/kg) and ibuprofen (50 mg/kg). Drug effects were assessed by radiologic and histopathologic examinations. The effects on hindpaw edema, hindleg function, and body weight gain were also evaluated. Treatment was initiated on day 16 after adjuvant injection and continued for 28, 56 or 84 days. The degree of relapse which occurred after a 28 day period without treatment following 28 or 56 days of treatment was also assessed. Etodolac prevented the progression of the disease. Further, it appeared to diminish the incidence and severity of the lesions already present on day 16 before drug treatment began. All the parameters measured were improved and there was good agreement between the radiologic and histopathologic assessments of joint damage. At the doses used, the onset of drug activity was more rapid with etodolac than with either of the other two drugs. By comparison naproxen and ibuprofen inhibited the progression of joint damage, but neither drug consistently decreased the magnitude of the joint damage below that of day 16. With all three drugs there was less resurgence of disease symptoms when treatment was stopped after 56 days rather than 28 days of drug administration.