Blood-pancreatic juice barrier to antibiotic excretion

Antibiotics were given intravenously to dogs with chronic pancreatic fistulas, and serum and pancreatic juice levels were measured. Despite adequate serum values, gentamicin, tetracycline, clindamycin, and moxalactam did not appear in the pancreatic juice, which suggested a barrier to their excretion. In contrast, chloramphenicol reached a peak concentration in the pancreatic juice that amounted to 36 percent of the peak serum value. In the pancreatic juice, ampicillin, cefoxitin, and cefamandole reached only 5 percent of the peak serum values but were still within the therapeutic range. TableII Peak Concentrations of Antibiotics in Serum and Pancreatic Juice (values expressed as the mean ± standard error of the mean) Antibiotic n Serum (μg/ml) Pancreatic Juice (μg/ml) Chloramphenicol 9 11.7 ± 1.4 4.2 ± 0.8 Ampicillin 4 89.1 ± 31.3 3.2 ± 2.7 Cetoxitin 7 60 ± 6.1 2.4 ± 1.2 Cefamandole 7 44.4 ± 8.1 2.4 ± 1.2 Gentamicin 4 9.5 ± 0.4 0.05 Tetracycline 5 11. 3 ± 2.4 2 Clindamycin 4 11.4 ± 2.3 2 Moxalactam 5 98.2 ± 14.4 2.5 We have concluded that there is a blood-pancreatic juice barrier to some antibiotics, which leads to selective excretion.