Abstract
Two cases in which hyperbilirubinemia produced falsely elevated aminoglycoside concentrations, using the Emit assay, are described. Patients' sera were analyzed by both the Emit and a microbiologic assay. The first patient had a 26-percent greater tobramycin concentration with the Emit assay, as compared with the microbiologic assay, when the total bilirubin was 20.1 mg%. For the same patient, there was essentially no difference between the two assays when the total bilirubin was 4 mg%. The Emit concentrations in the other patient were 34-percent elevated with a total bilirubin of 9.7 mg%. Pharmacokinetic analysis also was performed on serum levels reported by each method. Calculated kinetic parameters and dosage regimens varied greatly. Patients with total bilirubin concentrations > 4 mg% may need to have aminoglycoside serum levels assayed by a method other than the Emit assay. Drug Intell Clin Pharm 1983;17: 544–6.
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