Purpose: As H1 and H3 receptors' roles has been defined in peripheral pains in some papers and because histamine is known for its role in inflammatory responses; this study investigated the possible analgesic and anti-inflammatory effects of ketotifen and fexofenadine as relatively safe long acting anti histamines in both chronic chemical pain and acute inflammation in rats.
Methods: In this study, male Sprague-Dawley rats weighing 225-250 grams were used. In order to evaluate the chemical chronic pain, sub-plantar injection of formalin applied and the pain scores were recorded every 15 seconds during 60 minutes. Carrageenan injection to the right hind paw was used for induction of acute inflammation and the paw edema was measured every 60 minutes for 4 hours.
Results: Based on the results, both ketotifen and fexofenadine were able to significantly diminish chemical acute and chronic pain as well as inflammation in comparison with the control group and the effects were acceptable according to the standard treatment. Both effects for fexofenadine started later than those of ketotifen.
Conclusion: According to the outcomes of the study, ketotifen and fexofenadine demonstrated significant analgesic and anti-inflammatory characteristics in both models of chemical pain and acute inflammation in laboratory animals.
Keywords: Analgesic; Anti-inflammatory; Carrageenan test; Fexofenadine; Formalin test; Ketotifen.