The possible anti-inflammatory activity of macrolide antibiotics in some animal models

Recently, there has been increasing evidence on the use of macrolide antibiotics in treatment of chronic inflammatory diseases through mechanisms distinct from their antibacterial activity. The key desired effect lies somewhere between these two therapeutic potentials and has not been identified yet. The aim of the present study was to evaluate the anti-inflammatory activity of the macrolide antibiotic azithromycin in formaldehyde induced arthritis and carrageenan induced air pouch in albino rats in comparison to the anti-rheumatic drug meloxicam. Results of Formaldehyde induced arthritis revealed that pretreatment of animals with a single daily dose of either azithromycin (10, 20 and 40 mg/kg) or meloxicam (4 mg/kg) for 15 days produced a significant reduction in inflammation size. Histopathological study showed that Formaldehyde produced marked inflammatory cell infiltration, congestion of blood vessels and soft tissue edema which were attenuated by azithromycin in dose dependent manner. The radiological study revealed that azithromycin attenuates soft tissue edema, periarticular bone resorption, narrowing of joint spaces and joint deformities induced by formaldehyde. This effect was marked with 40mg/kg azithromycin pre-treatment. In carrageenan, induced air pouch, results demonstrate that group of animals pretreated with azithromycin (10, 20 and 40 mg/kg) or meloxicam (4 mg/kg) for 6 days significantly attenuated the mean increase in total leukocyte count in air pouch exudate. In conclusion, the present work showed that azithromycin has antiinflammatory activity in the models tested and suggests that it can exert therapeutics effects independent of its anti-bacterial activity. Also, the anti-inflammatory effect of azithromycin was potent and even comparable to that of meloxicam.