Kidney disease affects drug pharmacokinetics and pharmacodynamics, and level of kidney function is a key consideration in the use of drugs. Carboplatin, a widely used cancer chemotherapeutic agent, is excreted mainly by glomerular filtration. Maintaining efficacy and avoiding toxicity requires determination of glomerular filtration rate (GFR) for accurate dosing.1 In a recent study published in the Journal of Clinical Oncology, Janowitz et al2 evaluated the accuracy of GFR estimating equations in patients being treated with carboplatin and developed a new equation for the purpose of calculating a patient’s carboplatin dose to achieve a target exposure.