THIAMPHENICOL PHARMACOKINETICS IN SHEEP

The pharmacokinetics of thiamphenicol were investigated after intraven ous (i.v.), intramuscular (i.m.) and oral (p.o.) administration to she ep. It was found that the drug is almost completely absorbed following intramuscular injection, with a bioavailability of about 87.5%. Thiam phenicol appears to be widely distributed into extravascular compartme nts. yielding a volume of distribution [V(b)] of approximately 1 l/Kg. Elimination from the blood is relatively rapid, with a biological hal f-life of about 1. 5 h. Oral treatment showed that thiamphenicol is ab sorbed from the gastrointestinal tract yielding very low plasma concen trations which were maintained for at least 24 h. Although only 30% of the oral dose was systemically available. in contrast to chlorampheni col, thiamphenicol is truly absorbed when given orally to adult sheep. One possible reason for this observation is that rumen flora do not b iotransform this drug as they do for chloramphenicol. Metabolism inves tigations are. however, needed to confirm this finding.