Thesis (Ph.D.) - Cairo University - Faculty of Veterinary Medicine - Department of Veterinary Pharmacology

Values for pharmacokinetic variables are usually obtained in healthy animals, whereas drugs are frequently administered to diseased animals. This study investigated cefquinome pharmacokinetics in healthy goats and goats with experimentally induced mastitis. Five adult lactating goats received each of the following two treatments of 75mg of cefquinome intramammary infusion and intravenous injection before and after induction of clinical mastitis. Cefquinome concentrations were determined in plasma and skimmed milk samples using microbiological assay and high performance liquid chromatography. Pharmacodynamics was investigated using the California Mastitis Test, electrical conductivity, the sodium and potassium concentrations and pH of milk. Both MA and HPLC analytical methodologies yielded statistically similar mean values for the cefquinome concentration-time relationship in skimmed milk and plasma and similar values for almost all calculated pharmacokinetic indices; however, HPLC had a lower limit of quantification LOQ and coefficient of variation, and a higher correlation coefficient for standard curves. Experimentally induced mastitis decreased the maximal cefquinome concentration and shortened the elimination half-time in milk when compared to healthy goats. In conclusion, MA provides a simple, practical and inexpensive method for measuring cefquinome concentrations in skimmed milk and plasma samples from goats, while, HPLC proved to be more sensitive, specific and accurate. Mastitis facilitated the absorption of cefquinome from the mammary gland of lactating goats and induced marked changes in milk pH, sodium and potassium concentrations, which emphasizes the importance of performing pharmacokinetic studies in infected animals

Issued also as CD