[Immunological assay of sisomycin by fluorescence polarization]

Fluorescence polarization immunoassays (FPIA) of aminoglycoside antibiotics (gentamicin, tobramycin and amikacin) in plasma have been described. The use of sisomicin, a structural analogue of a C1a gentamicin fraction, is an alternative to gentamicin therapy for economical reasons. We have tested a therapeutic monitoring of this drug bases on FPIA using its croos reaction with gentamicin. Tracer (gentamicin labelled with fluorescein) and antisera were purchased from Abbott S.A. (gentamicin kit). Standard curves were obtained with sisomicin standard plasma samples. Within run and run-to-run precisions expressed as coefficient of variation were lower than 9.2 p. cent. The measurement of concentrations as low as 0.15 mg/l are possible. In order to evaluate specificity of this assay in clinical situation, we compared FPIA and liquid chromatography results.