Stability of gentamicin in serum.

Patients' sera were divided into three portions when the initial gentamicin level was determined and were stored at -20, 4, and 25 degrees C in plastic or glass tubes. Gentamicin levels were repeated after 1 and 2 days of storage at the respective temperatures. There was no significant difference in gentamicin levels among portions, except those from a patient in renal failure with high serum concentrations of carbenicillin.