Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2016
Publication Date: 11/28/2016
Publication URL: http://handle.nal.usda.gov/10113/5606394
Citation: Shelver, W.L., Schneider, M.J., Smith, D.J. 2016. Distribution of flunixin residues in muscles of dairy cattle dosed with lipopolysaccharide or saline and treated with flunixin by intravenous or intramuscular injection. Journal of Agricultural and Food Chemistry. 64:9697-9701. doi:10.1021/acs.jafc.6b04792.
Interpretive Summary: In a balanced design 20 dairy cows (5 cows per treatment group) were given 2.2 mg/kg of the anti-inflammatory drug flunixin by either intravenous or intramuscular and either saline or lipopolysaccharide (simulating infection). After a 4 day withdrawal period, the animals were sacrificed and thirteen different tissue types analyzed for flunixin. The results demonstrated flunixin concentrations were well below regulatory levels in most of tissues, but there was considerable variation with one animal’s levels well above the others across all tissue types and one tail sample also above others. Statistical analysis after elimination of these outliers showed that intramuscular injection gave higher levels than intravenous injection. In addition the presence of lipopolysaccharide lowered flunixin levels. The level of flunixin differed in the different muscle types. These results indicate definition of drug levels must take into account the tissue used. The results also indicate tissue levels are affected by route of administration or presence of lipopolysaccharide even after a withdrawal period.
Technical Abstract: Twenty dairy cows received flunixin meglumine at 2.2 mg/kg bw, administered once daily by either the intravenous (IV) or intra muscular (IM) route for three consecutive days with either intravenous normal saline (NS) or lipopolysaccharide (LPS) providing a balanced design with five animals per group. Cows were sacrificed after a 4 day withdrawal period and 13 muscle types were collected and assayed for flunixin by LC-MSMS. After elimination of sample outliers, main effects of route of administration (IV or IM), treatment (NS or LPS) and tissue type significantly (P < 0.05) affected flunixin residues, with no interaction (P > 0.05). Intramuscular (non-label) flunixin administration produced greater (P < 0.05) flunixin residues in muscle than the IV (label) administration whereas LPS resulted in lower flunixin levels. Differences among the tissue levels indicate it is necessary to specify the tissue to be used for any monitoring of drug levels for consumer protection.