The aim of the present study was to assess the analgesic activity of the macrolide antibiotic tilmicosin at dose levels of
20 and 40 mg/kg of body weight, subcutaneously, against chemical- and thermal-induced acute pains, using acetic acidinduced
writhing, formalin-induced pain, hot-plate, and tail-flick models in mice. Tilmicosin showed a dose-dependent
significant decrease in the number of writhes in the acetic acid-induced writhing test and significant decrease in hind pawlicking
time in the late phase of the formalin test. However, it did not cause any significant changes in the reaction times
to heat stimuli in the hot-plate and tail-flick models. In chemically-induced pains, both dose levels of tilmicosin showed
significant effects compared to those of the corresponding standard peripheral analgesic, acetylsalicylic acid (200 mg/kg
of body weight, subcutaneously) being 26.37 ± 2.88 and 43.64 ± 3.85% vs. 73.35 ± 1.44% in acetic acid test; and 19.23 ±
3.85 and 44.90 ± 1.80% vs. 73.63 ± 2.39% in the late phase of formalin test, respectively. These results may indicate that
tilmicosin possesses a significant peripheral but not central analgesic potential that may be beneficial in symptomatic relief
of pain when it is used in therapy, in addition to its well-established antibacterial effect.