Analgesia induced by ibuprofen and extract of XL E MS in preclinical murine assays

Several medicinal plants are used empirically as analgesics because their mechanism of action is not known. The study presented is related to the antinociceptive and anti-inflammatory properties of a crude extract of XL E MS that is used in different types of pain. The efficacy of the extract was compared with that of ibuprofen based on its ED50's of dose-response curves of each substance in the murine models of acetic acid writhing (WT), tail flick (TF), formalin hind paw (FHP), hot plate (HP) and Complete Freund´s adjuvant (CFA), tests. The data exhibit he following order of potency for ibuprofen: TF > CFA 1 DAY > CFA 7 DAYS > FHP II > FHP I > HP > WT. In the case of the XL E MS extract, the order of potency obtained was: CFA 7 DAYS > CFA 1 DAY > WT > FHP I > FHP II > HP > TF tests. The results demonstrate that XL E MS extract is less effective than ibuprofen in all the murine assay, with the exception of CFA 1 DAY, CFA 7 DAYS and WT. This difference could be due to the fact that the extract does not activate the same mechanisms or mediators of antinociception and anti-inflammation that ibuprofen triggers and the characteristics of the pain induced by each test. The results obtained suggest that although the effect of XL E MS extract is relatively moderate, it is useful as an analgesic-anti-inflammatory agent when used in traditional herbal medicine.