Antinociceptive effect of some biuret derivatives on formalin test in mice

The current study was designed to investigate the antinociceptive effects of several biuret derivatives with N, N`-diphenyl, N-phenyl-N`-alkylphenyl, N,N`-bis alkylphenyl, 2-methylquinoline-4-yl, benzo[d]thiazol-2-ylthio and (1-phenyl-1H-tetrazol-5-yl)thio substituents on the formalin-evoked pain in mice.

Antinociceptive activity of the nine biurets derivatives were assessed at different doses in mice using formalin test and the results were compared with those of indomethacin(20 mg/kg) and vehicle of the compounds. Area under the pain score curve against time (AUEC) up to 60 minutes was used as the measure of pain behavior.

A rather good analgesic effect was seen for most of the tested biuret derivatives. Significant reduction in median AUEC0-5 minutes was observed at the doses of 50 and 25 mg/kg for biurets with either benzyl and 2-methylquinoline-4-yl (C8) or phenylethyl and benzo[d]thiazol-2-ylthio(C9) moieties, respectively(p-value<0.0044). Antinociceptive activities of compound C7 (with bis phenylropyl substituent), C8 and C9 during the late phase of formaldehyde-induced pain were comparable to that of indomethacin.

Unlike indomethacin, the tested biuret compounds are able to induce antinociception in both phases of formalin test and could be considered comparable to indomethacin at the selected doses.