Atividade antinociceptiva de derivados 5-trifluormetil-4,5-diidro-1h-pirazol-1-carboxiamida em modelos animais de nocicepção aguda e crônica

Abstract

To identify the origin of pain and relieve of it is, certainly, important part of the treatment of any pathology. Unfortunately, nor all pain modalities possess an adequate treatment at a moment. Many patients do not obtain pain relief in response to drugs available or, they present serious adverse effects that hinder the continuity of treatment. So, a search for new drugs that are more efficient and that produce little undesired effect is necessary. Pyrazole derivatives are known for their excellent effectiveness as analgesics. In this context, the NUQUIMHE and LABNEURO have joined efforts for synthesize and evaluate the biological effects of several pyrazole compounds. In the present study, was evaluated the antinociceptive and antiedematogenic effect of one series of 5-trifluoromethyl-4,5-dihidro-1H-pyrazole-1- carboxiamide (2a-j) derivatives on acute and chronic nociception models in mice and rats. A preliminary evaluation of the toxicity for more active compounds, after their chronic administration, was carried out too. Some biochemistry parameters relationships to inflammation were also evaluated. Eight of ten compounds analyzed present antinociceptive effect on formalin test in mice. The two most efficient derivatives (2c and 2j) were also evaluated on hot plate, carrageenan and arthritis induced by Complete Freund Adjuvant (CFA). These compounds caused no effect against thermal nociception, but were effective for decrease the edema carrageenaninduced in mice. In the arthritis model in rats, 2c and 2j compounds caused antinociception, but do not antiedematogenic action. This antinociceptive effect occurred after acute and chronic administration and has long duration. Parameters indicators of liver and kidney lesion (urea, creatinine, aspartate aminotransferase and alanine aminotransferase) were not altered and were neither detected signals of gastric mucosa lesion nor evidences of tolerance development to antinociceptive effect in rats chronically treated with 2c or 2j. The serum level of haptoglobin and the tissue myeloperoxidase activity of the animals that received treatment indicate that these compounds did not present anti-inflammatory effect. None compounds evaluated caused alteration on locomotors activity of mice and rats. The results obtained in the present work suggest that this new class of pyrazole derivatives seems promising for development of new analgesic drugs.