Plasma adriamycin and daunorubicin levels by fluorescence and radioimmunoassay.

In 38 adriamycin experiments and 4 daunorubicin experiments, radioimmunoassay readily and reproducibly detects and estimates these drugs and immunologically similar metabolites in patients' plasma and urine to at least 120 hr after dosing without interference by concurrent medication. The plasma drug decay follows first-order kinetics in a triphasic pattern. Radioimmunoassay and fluorescence assay show similar decay up to 4 hr but diverge at that point with the fluorescence assay yielding higher values. Pharmocokinetic differences are amplified in patients with liver dysfunction and may be caused by fluorescent drug metabolites not sensitive to radioimmunoassay or nonspecific fluorescent materials. The radioimmunoassay offers the capability to measure adriamycin and daunorubicin in clinical settings in which fluorescence assay is not available.