[Evaluation of expected AUC of carboplatin (CBDCA) predicted by Chatelut's formula in comparison with Calvert's]

Several studies have shown that carboplatin AUC seems to correlate with therapeutic outcome and hematologic toxicity. Calvert's formula predicts carboplatin AUC using GFR estimated by the 51Cr-EDTA method. It is very complicated to manage radioactive agents, so we use 24-hour creatinine clearance before carboplatin administration as GFR in Calvert's. Recently, Chatelut reported a formula to predict carboplatin AUC using serum creatinine as a variable parameter of renal function as well as age, sex and body weight. We measured the AUC of free Pt by serial sampling in 14 ovarian cancer patients who received carboplatin by one-hour infusion in the initial treatment course. We evaluated the two predictive formulas with measured AUC. Calvert's predicted AUC showed a linear correlation with actual AUC (r = 0.768, p = 0.0013). But using Chatelut's formula, the predicted AUC had a better correlation with actual AUC (r = 0.833, p = 0.0002). Actual AUC correlated inversely with nadir PLT counts (r = -0.707, p = 0.0047). In conclusion, Chatelut's prediction had a better correlation with the actual AUC of carboplatin and nadir of thrombocyte count than Calvert's. Chatelut's formula was thus more useful to predict the carboplatin AUC than Calvert's when 24-hour creatinine clearance was used as GFR.