Pharmacokinetic evaluation and mammary excretion of tamethicillin in the healthy goat.

ABSTRACT

We evaluated the pharmacokinetics and the mammary excretion of a new beta-lactam antibiotic derivative, the diethylaminoethyl ester of methicillin, commonly known as tamethicillin. Tamethicillin is a hydrolyzable weak basic ester (pro-drug) that is converted to methicillin in the body. Its pharmacokinetic profile compares favorably with that of methicillin. In this sense, tamethicillin had five times greater distribution volume than methicillin, and both its slow phase half-time (t 1/2) and elimination half-time (t 1/2 Kel) were clearly greater. In addition, our experimental studies on mammary excretion in the goat have demonstrated a better selectivity for the udder of tamethicillin as compared with methicillin. Results of 2 years of field experience show that tamethicillin can be considered a useful alternative for the treatment of mastitis in livestock, especially in mastitis due to beta-lactamase-producing Staphylococcus.