Distribution of ivermectin residues in different Zebu cattle tissues and its stability in thermally processed canned meat.

Ivermectin (IVM) is one of the most widely used antiparasitic drugs worldwide and has become the drug of choice for anthelmintic and tick treatment in beef cattle production. Drugs used in production animals requires a withdrawal period after treatment to avoid residual concentrations above the defined maximun residue level (MRL). The aims of this study were to quantify the residue level of IVM in different muscles of cattle at several different time periods following 1% or 3.15% IVM administration and also determined whether the residue concentration was affected by industrial thermal processing. Distinct pattern of IVM residue distribution was observed in each tissue evaluated. After completed the IVM withdrawal periods, nearly all tissues presented IVM residues concentration below the established Codex Alimentarius MRLs, except for the injection site, which means that the calculation to determine the withdrawal period for the injection site should not be the same as that used for standard edible tissues. Also, the thermal processing to which canned products are exposed causes changes in the levels of quantified residues in comparison to raw products, which must be taken into consideration in surveillance program assessments and generates concerns regarding the possibility of residue limit violation in importing markets.