Effects of Topical Hydrocortisone and Acetylsalicylic Acid on the Primary Lesion of Adjuvant-Induced Arthritis

Abstract

Summary

Topical application of aspirin (6%) or hydrocortisone (2%) in hydroalcoholic solutions significantly reduced edema formation and local hyperpyrexia associated with the primary lesion of adjuvant arthritis in rats. Topical application of aspirin prior to and during the development of the primary lesion also significantly reduced adjuvant-induced body weight loss; whereas topically applied hydrocortisone aggravated body weight loss. Oral doses of aspirin (200 mg/kg) produced antiedema effects equal to those of topically applied aspirin (6%). In contrast to the topically applied aspirin, orally administered aspirin elevated pain threshold but failed to reduce adjuvant-induced body weight loss, and had significantly less effect on local hyperpyrexia. These results support the concept that the elevation in pain threshold (analgesia) produced by aspirin is due to a central effect rather than local anti-inflammatory activity; they also demonstrate that the adjuvant arthritic rat is a suitable model to detect and distinguish characteristics of topically effective antiinflammatory preparations.