Serum chloramphenicol concentrations in preruminant calves: a comparison of two formulations dosed orally

Abstract

Serum concentrations of chloramphenicol were determined after oral doses (55 mg/kg body weight) were administered to 7-9 day old Holstein-Friesian calves. Chloramphenicol in an oral solution produced greater serum concentrations than did an equivalent dose of chloramphenicol in capsules (P less than 0.005). A second dose of each formulation administered 12 h after the first dose elevated serum chloramphenicol concentrations significantly (P less than 0.001). The average serum chloramphenicol concentration exceeded 5 micrograms/ml of serum 1 h after administration of the solution compared with 4 h for the capsules. Average serum chloramphenicol concentration was greater than 5 micrograms/ml for at least 12 h after the dose was administered for both formulations. Of the eight calves receiving repeat doses of chloramphenicol, seven (87.5%) developed diarrhea in 76 +/- 8.6 h. Six of the eight calves (75%) died during or shortly after the period of chloramphenicol administration.

Modelo de indução de diarréia osmótica em bezerros holandeses

“…O modelo infeccioso para a indução da diarréia inclui o uso de cepas de Escherichia coli enterotoxigênica (HEATH et al, 1989), Criptosporidium parvum (TZIPORI et al, 1983), coronavírus (SAIF et al, 1986), rotavírus ou combinação de agentes infecciosos (NAYLOR, 1987). Os métodos não-infecciosos que têm sido utilizados, por via oral, para causar diarréia em bezerros são administração de sacarose (CONSTABLE et al, 1996;WALKER et al, 1998;CONSTABLE et al, 2000;FERREIRA, 2001), de lactose (HUBER et al, 1961), de sorbitol (NAPPERT et al, 1993), de manitol (FIORAMONT & BUENO, 1987), de neomicina, de ampicilina e tetraciclina (HUFFMAN et al;1981;MERO et al,1985) e de toxinas purificadas da Escherichia coli (ROUSSEL et al, 1988). Apesar de cada um desses modelos, com o uso de agentes infecciosos ou não, serem capazes de causar diarréia, a maioria não preenche os critérios desejáveis para um modelo ideal de indução da diarréia.…”