Effect of cefazolin on aminotransferase activity in the rat

Cefazolin given sc to male rats in daily doses of 0.5–2 g per kilogram of body weight significantly decreased alanine aminotransferase activity in serum, liver, kidney, heart, and brain 2–4 wk from the beginning of the treatment. Serum aspartate aminotransferase was also reduced, but serum alkaline phosphatase and tissue pyruvate decarboxylase activities remained unaltered. In female rates, daily sc administration of cefazoline at 0.1–1 g/kg also brought about a dose‐related reduction of alanine and aspartate aminotransferase activities, which reached statistical significance at high dose levels. The effect of cefazolin at low concentrations was partly reversed by administration of pyridoxal in vivo. Paradoxically, at higher dose levels pyridoxal potentiated the action of cefazolin on serum aminotransferases. The low enzyme activities were elevated by subsequent addition of pyridoxal 5´‐phosphate in vitro. Similar results were obtained when rats were treated with isoniazid at daily oral doses of 20 mg/kg;...