MED I C A L S CIEN T IF I C M AG A Z INE GroupT Vehicle control Diclofenac BIRM BIRM+diclofenac otal number of writhes 56.75±3.56 33.63±2.25***4 32±3.06***4 21.13±2.78***# Inhibition (%) 4 1 63 Table 1: Effect of repeated administration of BIRM on nociception induced by acetic acid in writhing test. Data represented as mean±SEM. ***p<0.001 as compared to vehicle control; #p<0.05 as compared to diclofenac (ANOVA followed by Tukey’s multiple comparison test), BIRM: Biological immune response modulator. SEM: Standard error of the mean post-test. reduction in overall pain response, which includes frequency of fl inching, biting, licking, and paw lifting in Phase 1 and Phase 2 as compared to vehicle control. Gabapentin, when administered as a single i.p. dose produced signifi cant reduction in pain response in Phase 1 (p<0.01) and Phase 2 (p<0.001) as compared to vehicle control but to a lesser extent as compared to BIRM in Phase 2 (Table 3 and Figure 3). This observation with respect to gabapentin is in could signifi cantly reduce the occurrence of writhes (63%) as compared to vehicle control (p<0.001) (Table 1 and Figure 1). Discussion Figure 2: Effect of repeated administration of biological immune response modulator (4 ml/kg, p.o. for 7 days) on infl ammation induced by intraplantar injection of carrageenan in hind foot pad of Swiss Albino mice. *p<0.05 and ***p<0.001 as compared to vehicle control. Data were analyzed using two-way repeated measure ANOVA followed by Bonferroni Carrageenan induced paw edema test The intra-plantar administration of carrageenan induced gradual increase in paw edema. Repeated oral treatment of BIRM (4 ml/kg) for 7 days signifi cantly reduced the carrageenan-induced paw edema at 2 hrs (p<0.05), 3 hrs, 4 hrs, and 5 hrs (p<0.001) post carrageenan treatment as compared to vehicle control. BIRM exhibited highest reduction of 71.89% in paw edema at 5 hrs post carrageenan treatment. As reported, diclofenac too showed a signifi cant reduction in paw edema at 3, 4, and 5 hrs (p<0.001) post carrageenan treatment as compared to vehicle control (Table 2 and Figure 2).14,15 Formalin-induced paw licking test The repeated administration of BIRM orally for 7 days prior to formalin administration resulted in a signifi cant (p<0.001) Figure 3: Effect of repeated administration of biological immune response modulator (4 ml/kg, p.o. for 7 days) on pain behavior induced by formalin in the formalin test. **p<0.01 and ***p<0.001 as compared to vehicle control.#p<0.01 as compared to gabapentin. ANOVA followed by Tukey’s multiple comparison test. line with the reported data where Phase 2 is concerned.12,16 In the current study, in order to ascertain BIRM’s peripheral analgesic activity and its anti-inflammatory property we employed the acetic acid-induced writhing test and carrageenan-induced paw edema test, respectively. Moreover, formalin-induced paw licking test was used to confi rm whether BIRM’s anti-nociceptive property is mediated through central or peripheral nervous system. Acetic acid-induced writhing test was mainly performed to assess the peripheral analgesic activity of the compound in question. In general, acetic acid causes spontaneous pain by secretion of endogenous substances such as serotonin, histamine, prostaglandins (PGs), bradykinins, and substance P Deraedt et al.17 have shown increased presence of PGE2 in the peritoneal fl uid post acetic acid administration. PGs along with local peritoneal receptors are thought to be responsible for abdominal constriction and activation and sensitization of the peripheral chemo-sensitive nociceptors18-20 and causing infl ammatory pain.21 BIRM signifi cantly reduced the frequency of the writhing in mice subjected to i.p acetic acid administration, similar to the conventional NSAID diclofenac sodium. BIRM as standalone treatment was found to be equally effi cacious as compared to standard diclofenac, but BIRM when administered as combination therapy along with diclofenac was found to be more effective in terms of inhibition of writhes as compared to BIRM or diclofenac alone. Carrageenan induced infl ammation model is used extensively in the development of NSAIDs and selective COX-2 inhibitors and in assessing the contribution of mediators involved in vascular changes associated with acute infl ammation.22 Carrageenan-induced paw edema test, commonly used as an experimental model for acute infl ammation, is observed to be biphasic. Acute infl ammation observed in both phases leads to leakage of plasma elements from blood vessels to BIR M 25