Comparison of analgesic, anti-inflammatory and anti-pyretic efficacy of diclofenac, paracetamol and their combination in experimental animals

Background: Various combinations of analgesics antipyretic drugs are available in the market for treatment of various musculoskeletal disorders and pain relief. Diclofenac and paracetamol combination is most commonly used combination and its rationality is questionable. The objective of this study was to compare the analgesic, anti-inflammatory and anti-pyretic activities of diclofenac, paracetamol and their combination. Methods: Experimental animals were divided into 4 different groups – control, diclofenac, paracetamol and their combination. Analgesic activity was compared by using tail-clip method in rats and writhing test in mice, anti-inflammatory activity was compared by carrageenan paw edema method using plethysmometer and anti-pyretic action was compared using TAB vaccine induced pyrexia and measuring the rectal temperature. Different doses of diclofenac (1mg/kg and 2mg/kg) and paracetamol (10mg/kg and 20mg/kg) used and same doses were used in combination group. Results: Diclofenac sodium (1mg/kg) showed significantly higher analgesic activity using tail-clip and writhing method compared to paracetamol (10mg/kg) (p<0.0001) and the combination group (p<0.05). Diclofenac sodium (2mg/kg) showed significantly higher analgesic activity using tail-clip and writhing method compared to paracetamol (20mg/kg) (p<0.0001) and the combination group (p<0.1). Diclofenac has no significant difference in anti-inflammatory activity using carrageenan induced paw edema when compared to the combination group (p<0.1) for both doses. But diclofenac when compared to paracetamol for anti-inflammatory effect, it was highly significant (p<0.0001 and p<0.0004) for both doses at 1 st and 3 rd hour. Paracetamol 20mg/kg was superior antipyretic (p<0.05,0.01 and 0.01 ) when compared to the combination group at 1hr, 2hr and 3hr duration after injecting TAB vaccine. Conclusion: Diclofenac and paracetamol combination was either equal or inferior in all three activities studied as compared to the individual drugs.