FACTORS AFFECTING EPIRUBICIN PHARMACOKINETICS AND TOXICITY - EVIDENCEAGAINST USING BODY-SURFACE AREA FOR DOSE CALCULATION

Purpose: An exploratory study to test whether body-surface area (BSA) should be used for the calculation of epirubicin dose. Patients and Me thods: The relationship between pretreatment characteristics and the e ffects of epirubicin were investigated in 20 chemotherapy-naive patien ts. Measurements of body size, renal and hepatic function, and or her factors were correlated with epirubicin pharmacokinetics (PK) and epir ubicin-induced neutropenia, All patients received 150 mg of epirubicin infused continuously over 120 hours, regardless of body size. Factors were analyzed by univariate and multivariate linear regression. Resul ts: There were no correlations between BSA or weight with any PK param eter or with the degree of neutropenia. In multivariate analysis, indi cators of liver function were the only factors that correlated with ne utropenia and epirubicin PK. Thus, correlations for neutropenia were s een with antipyrine clearance (P = .003), activated partial thrombopla stin time (APTT) (P = .005) and serum transferrin (P = .01). Further, the area under the concentration-time curve (AUC) for epirubicin corre lated with prothrombin index (P < .01), antipyrine clearance (P < .01) , and serum bile salt concentration (P = .03), and there were similar correlations for epirubicin steady-state concentration (CpSS). Epirubi cin clearance correlated with antipyrine clearance (P = .02). PK param eters for dihydroepirubicin correlated with prothombin index, serum tr ansferrin, and bile salt concentrations (P < .001 for all correlations ), Because of the number of statistical examinations performed, some o f these correlations may be spurious. However, some are likely to be r eal, since the same variables repeatedly correlated with different epi rubicin-associated outcomes. There were no correlations between epirub icin PK indices or neutropenia and serum aminotransferase levels or ot her biochemical liver function rests, creatinine, or any of the clinic al factors examined. Conclusion: These results led vs to question the use of BSA for epirubicin dose calculation. In contrast quantitative l iver function tests may give a better indication of drug handling and toxicity and may be useful to determine more accurate methods for dose calculation of epirubicin. (C) 1998 by American Society of Clinical O ncology.