Comparative toxicity of gentamicin and cefotetan

In a prospective, randomized, comparative study, the renal, hepatic and gastrointestinal toxicity and effects on the vitamin K dependent coagulation factors of gentamicin and cefotetan were compared. Gentamicin, which in all but one patient was combined with a penicillin, was found to cause a significant decrease of glomerular filtration rate (GFR) after 1 week of treatment. In 6/14 patients a further decrease of GFR was found during the week following the last treatment day. The renal proximal tubular cells were affected by gentamicin, as evident from significant increases in urinary activity of 2 tubular enzymes, alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG), as well as rises of urinary beta 2-microglobulin. Changes in GFR and tubular function were reversible. No statistically significant changes of these variables were seen with cefotetan. One cefotetan treated patient developed diarrhoea of moderate severity and 2 patients in the same group developed minor increases of liver transaminases. A small but statistically significant decrease of the activity of the vitamin K dependent coagulation factors occurred during cefotetan treatment. No gastrointestinal or hepatic adverse reactions were observed in the gentamicin treated patients.