Abstract

Angiotensin Receptor Antagonists (ARAs) are widely used compounds in various cardiovascular disorders like Hypertension, Stroke prophylaxis, Heart failure. In addition, they are approved for the treatment of Diabetic Nephropathy. It is reported to produce analgesia on intracerebro-ventricular administration that could be blocked by naloxone. Angiotensin II has been reported for its pro-nociceptive activity. Angiotensin receptor antagonists block the action of angiotensin II by inhibiting its binding with its receptor hence, they exerts analgesic activity. The analgesic activity of angiotensin antagonists Losartan, Irbesartan and Valsartan evaluated by tail immersion, tail flick and tail clip methods have shown significant increase in basal reaction time. Pentazocine, a kappa receptor agonist exerted a significant analgesic effect (p<0.001). In comparison to control, angiotensin antagonists Losartan, Irbesartan and Valsartan show significant reduction in time for onset of writhing and also number of writhing. The % inhibitions of writhing for Losartan, Irbesartan and Valsartan at a dose of 20 mg/kg were 74, 68 and 73%, respectively, whereas Aspirin (100 mg/kg) has 83% inhibition. All the three drugs have shown significant p value (p<0.001) which is comparable to standard control

Key words: Angiotensin antagonist, Losartan, Irbesartan and Valsartan.