Amikacin: a Rapid and Sensitive Radioimmunoassay

Abstract

A rapid, sensitive, and specific radioimmunoassay has been developed for the measurement of amikacin, a new semisynthetic aminoglycoside antibiotic. Antisera were produced by immunizing rabbits with amikacin conjugated to porcine thyroglobulin. Sera were screened for amikacin antibodies with ³ H-labeled amikacin. Free and bound radioactivity were separated by the second antibody method. As little as 5 ng of the antibiotic can be measured in serum, cerebrospinal fluid, and urine. The standard curve is unaffected by pH (5–11), ionic strength (0.01 M to 0.3 M), MgCl ₂ or CaCl ₂ (1 to 8 mM/liter), or urea (10–300 mg/100 ml). The antibodies raised to amikacin are not able to distinguish between kanamycin and amikacin. The cross reactivity of all other antibiotics tested was stat determinations. The standard curve is linear on a logit-log plot, allowing for rapid computer analysis of the standard curve, interpolation of sample values, and quality-control monitoring.