Dose adjustment of carboplatin in patients on hemodialysis

Carboplatin is one of the most prescribed cytotoxic drug, which is extensively used in the treatment regimens of several malignancies. The therapeutic efficiency of carboplatin has been found to correlate the area under curve (AUC). The Calvert formula has been extensively used to determine the dose of carboplatin for a fixed AUC and glomerular filtration rate (GFR). This formula has also been used in patients with end-stage renal disease on hemodialysis by assuming that the GFR is zero. This is applicable to patients who receive hemodialysis within 12-18 h after carboplatin infusion. After the first 24 h, a majority of the carboplatin is bound to proteins is not easily dialyzable and hence continues to remain in the blood stream despite repeated sessions of hemodialysis. We derive a correction factor to calculate the resultant AUC in such patients. The analysis done by using this correction factor shows that the AUC can increase by eightfold in patients who received the adjusted dose but whose hemodialysis was delayed beyond 24 h after infusion. The correction factor proposed here can also be used to calculate the dose adjustment required a priori in patients who may receive delayed hemodialysis. It is also useful to predict the AUC and estimate the resultant toxicity in such patients.