Comparative analgesic effects of paracetamol with paracetamol-caffeine formulation

This study was designed to evaluate the contribution of caffeine to analgesia in paracetamol-caffeine preparation. Analgesic properties were evaluated in mice using acetic acid-induced writhing and hot plate methods. In the acetic acid method, the test drugs were administered orally to the mice. After 30 min. all the mice received 0.7% aqueous solution of acetic acid (10ml/kg i.p) and writhing was counted for 30 min. after acid injection. The percentage inhibition was then determined. In the case of hot plate method, the mice were placed singly on a hot plate maintained at 45±0.50C before and at 15, 30, 45, 60 and 90 min. after administration of the tested drugs orally. The latency of nociceptive responses (time taken before the mouse jumped out of the hot plate) was measured each time the mouse was placed on the hot plate. The mean percentage maximum possible effect (% MPE) was determined. The results revealed dose dependent analgesic activities in both paracetamol alone and paracetamol-caffeine combination. The activities were significantly higher compared to the control which received normal saline (p