It is known that elemental impurities (EI) do not provide any therapeutic benefit to the animals, their levels in the drug product should be controlled within acceptable limits in order to guarantee the animal safety and the consumer safety, taking food of animal origin (meat, eggs, milk, cheese..).
Based on their likelihood of occurrence in the drug products and their toxicity, the elements have been classified in 3 classes in ICH Q3D. Based on the main route of administration the table 5.1 of ICH Q3D define the elemental impurities, divided in the 3 classes, that are acceptable in Veterinary Medicinal Products. The most important elemental impurities to consider are those listed in ICH Q3D: Cd, Pb, As, Hg, Co, V, Ni, Tl, Au, Pd, Ir, Os, Rh, Ru, Se, Ag, Pt, Li, Sb, Ba, Mo, Cu, Sn, Cr.
The Permitted Daily Exposure, that gives, based on the toxicity data, the maximum permitted quantity of each element that may be contained in the maximum daily intake of a medicinal product, needs to be converted into a maximum concentration of impurities in the VMPs, following the approach proposed in the guidance. If potential elemental impurities are identified, specific test needs to be conducted to quantify them and determine if they respect or not the maximum acceptable limits. Levels of elemental impurities higher than the established PDE may be justified in certain circumstances, for example with reference to the route of administration, target species, weight of the target species, dose and duration of treatment. In certain circumstances, a toxicological evaluation may be required. Such higher levels are subject to authority approval.