RESIDUES OF CLENBUTEROL IN CATTLE RECEIVING THERAPEUTIC DOSES - IMPLICATIONS FOR DIFFERENTIATING BETWEEN LEGAL AND ILLEGAL USE

Clenbuterol (CBL) can be used legally in the treatment of respiratory diseases and illegally as a growth promoter in animals, Liver and eye have previously been shown to be effective matrices for the detection of residual concentrations of the drug. The pharmacokinetics of CBL in therapeutically treated cattle were investigated, During treatment, m any body fluids and tissues contained residues of the drug, After a 14 day withdrawal only eyes (mean 27.1 ug/kg), and to a much lesser exte nt lung and kidney (mean 0.3 ug/kg), contained detectable residues. By day 28 of withdrawal only residues in eyes were present (mean, 6 ug/k g), These persisted to the end of the tria1(42 days withdrawal). It is concluded that it is not possible to differentiate between the legal and illegal use of CBL solely on drug residue analysis, Other informat ion must be made available to regulatory bodies to enforce control pro grammes.