Dexamethasone and flumethasone residues in milk of intramuscularly dosed cows.
A field study was performed to assess the level of drug residues in milk after therapeutic application of highly potent synthetic glucocorticoids. Dexamethasone was tested either as a crystalline suspension or as a combination of sodium phosphate and phenylpropionate esters. Intramuscular injection of these preparations in lactating dairy cows (60 micrograms dexamethasone/kg body wt) yielded drug residues in milk of up to 8.4 ng/mL 12 h after treatment. These dexamethasone residues fell to below 1.0 ng/mL within 3 days after treatment. Intramuscular injection of an aqueous flumethasone preparation (13.5 micrograms/kg body wt) produced drug residues in milk in the range of 0.7-1.2 ng/mL 12 h after treatment, whereas flumethasone was below the detection limit of 0.23 ng/mL 2 days after administration. These results indicate that toxicologically significant residues may arise transiently in the milk during the first 2-3 days after intramuscular injection of synthetic glucocorticoids. Urine from the same animals contained 5- to 50-fold higher glucocorticoid concentrations than the corresponding milk samples. Thus, urine analysis appears to be an effective method to monitor the use of synthetic glucocorticoids in food producing animals.
Reding
J
J
Institute of Veterinary Pharmacology and Toxicology, University of Zürich, Switzerland.
Sahin
A
A
Schlatter
J
J
Naegeli
H
H
D000818:Animals; D002417:Cattle; D003907:Dexamethasone / Q000032:analysis* / Q000627:therapeutic use; D004350:Drug Residues / Q000032:analysis; D005260:Female; D005443:Flumethasone / Q000032:analysis* / Q000627:therapeutic use; D005938:Glucocorticoids / Q000032:analysis* / Q000627:therapeutic use; D007273:Injections, Intramuscular; D008892:Milk / Q000737:chemistry*
D005938:Glucocorticoids; D003907:Dexamethasone; D005443:Flumethasone