Determination of sisomicin, netilmicin, astromicin and micronomicin in serum by high-performance liquid chromatography.

A high-performance liquid chromatographic method for monitoring serum levels of the aminoglycoside antibiotics sisomicin, netilmicin, astromicin, and micronomicin, using an amino acid analysis system is described. The procedure involves sample preparation with a CM-Sephadex column, and quantitation using internal standards chosen from each of the other aminoglycosides. The aminoglycosides were separated by reversed-phase ion-pair chromatography on Zorbax C8 and ODS columns, and detected by the post-column derivatization technique. The calibration curves of serum concentration for sisomicin, netilmicin, astromicin, and micronomicin were linear over the ranges 0.32-22.8 micrograms/ml, 0.17-11.6 micrograms/ml, 0.1-6.3 micrograms/ml, and 1.0-30 micrograms/ml, respectively. The coefficients of variation were 2.5, 2.8, 3.1 and 1.9%, at the serum concentrations of 1.3, 1.45, 1.58 and 2.5 micrograms/ml, respectively (n = 6). Determination by the internal standard method using another aminoglycoside gives accurate and reproducible results. This method is applicable also to other aminoglycoside antibiotics.