Residues of veterinary drugs at injection sites

Abstract

Residues of veterinary drugs have potential implications for human food safety and international trade in animal-derived food commodities. A particular concern is the slow depletion of residues of some injectable formulations from the site of administration. Licensing authorities have adopted different approaches to the human food safety assessment of injection site residues. European agencies apply the maximum residue limit (MRL) for muscle to muscle at the injection site and specify a withdrawal period sufficient to ensure the ingestion of a 300 g portion of muscle, if comprised entirely of injection site tissue, does not exceed the acceptable daily intake. The agencies in Australia, Canada and the USA also exclude injection site residues from the MRL-setting process. These agencies evaluate the risk to consumers posed by potential acute manifestations resulting from the infrequent ingestion of injection site residues based on acute dietary exposure considerations. While all of these approaches protect the safety of consumers, the adoption of different approaches has potential implications for residue surveillance programs in the international trade in meat. In particular, when an exporting country establishes standards for residues at injection sites based on acute dietary exposure considerations and the importing country assesses these residues against the MRL for muscle, the unnecessary condemnation of meat and disruption to market access may result. The latter may represent a potential economical impost to the exporting country. An internationally harmonized approach to the risk analysis of residues of veterinary drugs at injection sites, which protects the safety of consumers and facilitates the international trade in meat, is needed.

The role of pharmacokinetics in veterinary drug residues

“…This fraction may be subject to very slow and erratic absorption . The lack of consistency between regulatory authorities in addressing the issue of injection site residues has been discussed by Reeves …”

Pharmacological treatments and risks for the food chain

“…The primary issue is consumer safety in view of the potential acute consequences resulting from the ingestion of injection site residues. Licensing authorities have adopted different approaches to the human food safety assessment of injection site residues (Reeves 2007). European agencies apply the maximum residue limit for muscle tissue to the muscle injection site and specify a withdrawal period sufficient to ensure that ingestion of a 300 g piece of muscle, even if it were comprised entirely of injection site tissue will not exceed the acceptable daily intake (ADI).…”

“…These authorities evaluate the risk for consumers to develop potential acute manifestations after infrequent ingestion of injection site residues based on acute dietary exposure estimates. In this case, the ADI is substituted by the ARfD (Acute Reference Dose), the total dose of residues of a chemical in the food that can be ingested over a short period, usually one meal or one day, without appreciable health risk to the consumer (Reeves 2007).…”

Veterinary drug residues in foods

“…This procedure for tissues and milk can be found in EMEA/CVMP/036/95 and EMEA/CVMP/473/98, respectively. For injection site residues, the EMA issued a specifi c guideline, since residues at injection sites commonly deplete erratically (EMEA/CVMP/542/03), as reviewed by Reeves (2007) and Sanquer et al (2006b). Sanquer et al (2006a) assessed the risk related to the consumption of a whole or part of an injection site during a year using a probabilistic approach.…”