Practical approach for the stability testing of veterinary drugs in solutions and in biological matrices during storage Original Research Article

According to the SANCO/1805/2000 document and the EMEA/CVMP/573/00 guideline, one of the performance characteristics to be determined for an analytical method is the analyte stability. A practical approach is presented for the stability testing of veterinary drugs in solvents and in biological matrices during storage. These drugs comprise analytes belonging to the classes of antibiotics, sulfonamide chemotherapeutics, anthelminthics and non-steroidal anti-inflammatory drugs. Examples of the stability in solution are given for clindamycin, ketoprofen, oxytetracycline, 4-epioxytetracycline, sulfadiazine, trimethoprim, tylosin A and their respective internal standards. For the stability in matrix during storage, plasma or tissues are fortified with the analyte. Results of the recovery after storage are shown for amoxycillin in pig tissue, doxycyclin, sulfachloropyridazin and trimethoprim in broiler tissue and clindamycin, closantel, doxycyclin and ketoprofen in animal plasma. The analysis of incurred plasma samples containing closantel revealed that the temperature at which the samples are processed is critical. Compounds are analyzed by liquid chromatography with UV or tandem mass spectrometric detection.