Analgesic and anti-inflammatory effects of minocycline in chicks

Abstract

Minocycline is a second-generation tetracycline that has a variety of nonantimicrobial properties. This study aimed to assess the analgesic and anti-inflammatory activities of minocycline in chicks. The median lethal dose and median analgesic dose of minocycline were determined using the up-and-down method; the analgesic effects over time were evaluated using the electrostimulator device; the acute analgesic and anti-inflammatory activity was assessed using the formalin test; and the chronic anti-inflammatory activity of minocycline was determined using the cotton pellet test. The median lethal dose and median analgesic dose of minocycline were 1278 and 74 mg/kg, respectively. Minocycline 150 and 300 mg/kg, orally, produced significant analgesia in a dose-dependent manner, and the peak of analgesia was observed at two hours and continued for more than eight hours after treatment. In the formalin test, minocycline 150 and 300 mg/kg, amended the pain by increasing the onset and decreasing the frequency of raising the right foot in comparison to the control. The formalin test demonstrated the anti-inflammatory activity of minocycline by inhibiting the percentage of inflammation compared to the control by 43% and 66%, respectively. Minocycline 150 and 300 mg/kg suppressed chronic inflammation, as measured by the cotton pellet test, and the inhibition percentages in wet and dry cotton pellets were 14% and 18%, and 30% and 44%, respectively. In conclusion, minocycline has analgesic effects on acute pain and anti-inflammatory effects on acute and chronic inflammation in chicks.