FDA Video: New Precaution when Calculating Carboplatin Doses

FDA is informing oncologists that recent changes in how serum creatinine is measured could lead to the wrong carboplatin dose.

All clinical labs in the U.S. will soon be using a newly standardized method to measure serum creatinine -- Isotope Dilution Mass Spectroscopy (IDMS). Compared to older methods, IDMS appears to underestimate serum creatinine levels when serum levels are relatively low, for example, around 0.7 mg/dL. This could result in overestimating the Glomerular Filtration Rate (GFR) in some patients with normal renal function. And that in turn could to lead patients being given a carboplatin dose that's higher than needed, which increases the risk of drug toxicity.

To avoid this possibility, FDA recommends that when GFR is estimated based on serum creatinine using the IDMS method, the carboplatin dose should be capped. The maximum dose should be based on a GFR estimate of no more than 125mL/min for patients with normal renal function.

Capping the dose is not necessary when the patient's renal function is assessed using actual GFR measurements. In these cases, carboplatin can be safely dosed according to the instructions in the drug's labeling.