الكاتب: Multiple References

Despite the use of penicillin G for many decades to treat lactating cows and the feeding of the withheld milk to calves, no de®nitive studies could be found on the bioavailability or disposition of penicillin G in the calf after ingestion of milk containing subtherapeutic concentrations of penicillin G. Research has been published on the bioavailability of other b-lactams in the calf (Larkin, 1972; Palmer et al., 1977; Ziv et al., 1977; Ziv & Horsey, 1979; Palmer et al., 1983; Soback et al., 1987), but not penicillin G. Penicillin G is degraded in the stomach by gastric acid resulting in limited absorption, however, the reported percentage of the dose absorbed (bioavailability) is quite varied (Huber, 1982; Knifton, 1982; Riviere et al., 1991; Nathwani & Wood, 1993; Rang et al., 1995; Mandell & William, 1996). The possibility of penicillin G causing drug residues when calves are fed waste milk has been suggested (Kesler, 1981). A few studies (Yndestad & Helmen, 1980; Prange et al., 1984; Musser & Anderson, 1998; Musser et al., 2001) investigated the presence of penicillin G in urine, tissue, and blood, but the authors are unaware of studies examining the pharmacokinetics of penicillin G when administered concurrently with milk. This study investigated the age related disposition kinetics and bioavailability of penicillin G when administered intravenously and orally with milk.