RESUMEN
Syzygium aromaticum (L.) Merr. & L.M. Perry (Mirtaceae) and Rosmarinus officinalis L. (Lamiaceae) are both medicinal plants used for centuries to alleviate pain. The aim of the study was to demonstrate the therapeutic potential utility of herb-drug association of S. aromaticum essential oil or R. officinalis ethanolic extract coadministered with ketorolac. Antinociceptive pharmacological interaction was investigated by an isbolographic study using the formalin test in rats. Both alone and in combination with ketorolac; S. aromaticum and R. officinalis produced a dose-dependent antinociceptive response. To plot the isobologram, we used the effective dose 50 of each one component in a fixed 1:1 ratio. The isobolographic analysis showed that, in both combinations, ketorolac plus essential oil S. aromaticum and ketorolac plus ethanolic extract R. officinalis, the experimental value (Zexp) was lower than the theoretical value (Zadd). In addition, this study shows that eugenol, a metabolite present in S. aromaticum, and ursolic acid, a metabolite present in R. officinalis, also synergized the antinociceptive effect of ketorolac. While, the oleanolic acid present in both medicinal species did not show a synergistic antinociceptive effect in combination with ketorolac. No adverse effects were observed with these herb-drug interactions. These findings suggest that essential oil S. aromaticum and ethanolic extract R. officinalis could be useful in combination with ketorolac for the treatment of inflammatory pain.