Pharmacokinetics of polymyxin B administered via the bovine mammary gland.
Polymyxin B was infused into normal, chronically inflamed, and acutely inflamed quarters of the mammary gland of lactating cows at dosages ranging between 1 and 2 million units (100-200 mg) per quarter. Samples of milk from treated and non-treated quarters, jugular venous blood, subcutaneous abdominal (mammary) venous blood, and urine were collected at intervals after treatment and were assayed using microbiological test methods for polymyxin B concentrations. The drug was not absorbed from normal and chronically inflamed quarters; more than 90% of the infused dose was recovered in milk within 24 h after treatment, and drug residues were detected up to the ninth milking. Drug concentrations in milk from acutely inflamed quarters were significantly lower than in milk from normal quarters; 55% of the infused dose was recovered in the milk within 24 h after treatment. The drug was detected in milk from non-treated quarters, in blood from the subcutaneous abdominal vein, and in the urine during 36-48 h after acutely inflamed quarters were infused with the drug. These data indicate that polymyxin B is well distributed throughout, and is absorbed to a significant degree into the systemic circulation from the acutely inflamed udder.
D000042:Absorption; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D005260:Female; D007700:Kinetics; D008321:Mammary Glands, Animal / Q000378:metabolism*; D008414:Mastitis, Bovine / Q000378:metabolism; D010400:Penicillin G / Q000378:metabolism; D011112:Polymyxin B / Q000008:administration & dosage / Q000378:metabolism*; D011113:Polymyxins / Q000378:metabolism*
D011113:Polymyxins; D011112:Polymyxin B; D010400:Penicillin G