Evaluation of the anti-inflammatory activity of dipyridamole in acute and chronic experimental models in albino rats

Background: Cyclic nucleotides, particularly cyclic AMP, have an important regulatory role in a variety of inflammatory processes. The concentration of cAMP can be influenced by either inhibition of phosphodiesterase enzyme or by activating adenylate cyclase enzyme. The present study was undertaken to evaluate the anti-inflammatory activity of dipyridamole a selective (PDE6) phosphodiesterase inhibitor; on acute and chronic experimental models in albino rats.Methods: Anti-inflammatory activity was evaluated by using carrageenan-induced rat hind paw oedema model for assessing acute anti-inflammatory activity. The normal paw volume (0 hour) and the volume of injected paw (3 hour) were measured by using plethysmometer. Assessment of chronic anti-inflammatory activity was carried out using formalin-induced rat paw edema model. The paw volume was measured at 0 hour and on 7th day after injection of formalin by using plethysmometer. The results obtained were compared with the control and the standard anti-inflammatory drug, indomethacin.Results: The results indicated that dipyridamole has anti-inflammatory action in both acute and chronic inflammatory models. But statistically significant anti-inflammatory action was seen only with the chronic inflammatory model (0.11±0.05 units, p=0.02). Anti-inflammatory activity could be due to inhibition of inflammatory cells and mediators especially histamine, leukotrienes and eicosanoids.Conclusions: Selective phosphodiesterase inhibitors could be a source of valuable anti-inflammatory drugs, in addition to currently available steroidal and non-steroidal anti-inflammatory agents