Carboplatin Dose Calculator (Calvert Formula)
Calculate the carboplatin dose with the Calvert formula — dose (mg) = target AUC × (GFR + 25) — from a measured GFR or Cockcroft-Gault creatinine clearance, with the FDA cap of GFR 125 mL/min.
How it works
Calvert: dose (mg) = target AUC (mg/mL·min) × (GFR (mL/min) + 25) · Cockcroft-Gault CrCl = (140 − age) × weight (kg) ÷ (72 × creatinine mg/dL) [× 0.85 if female] · FDA: cap GFR at 125 mL/min, so maximum dose = AUC × 150 mg
Carboplatin is cleared almost entirely by glomerular filtration, so Calvert and colleagues (J Clin Oncol 1989) showed that dosing by kidney function rather than body surface area hits a predictable exposure: total clearance ≈ GFR + 25 mL/min (the 25 accounts for non-renal clearance). The target AUC is set by the regimen — commonly 5–6 with paclitaxel for ovarian or lung cancer, 2 weekly with radiation. Since standardized (IDMS) creatinine assays read lower and can overestimate GFR, the FDA advises capping the GFR at 125 mL/min, which limits the dose to AUC × 150 mg. Many centers also set a minimum creatinine (for example 0.7 mg/dL).
Worked example
A 60-year-old woman weighing 70 kg with creatinine 70 µmol/L (0.79 mg/dL) and a target AUC of 5: Cockcroft-Gault clearance = (140 − 60) × 70 ÷ (72 × 0.79) × 0.85 = 83.5 mL/min, below the 125 cap, so the dose is 5 × (83.5 + 25) = 543 mg. The maximum possible dose at AUC 5 is 750 mg.
Sources: Calvert AH et al. Carboplatin dosage: prospective evaluation of a simple formula based on renal function. J Clin Oncol 1989;7:1748–56 · FDA: Carboplatin dosing — follow-up communication on creatinine (IDMS) and GFR cap
Frequently asked questions
What is the Calvert formula?
Carboplatin dose (mg) = target AUC × (GFR + 25). The dose is a total in milligrams, not per m². For example AUC 6 with a GFR of 100 mL/min gives 6 × 125 = 750 mg.
Why cap the GFR at 125 mL/min?
After US labs standardized creatinine assays (IDMS) in 2010, creatinine values became lower and estimated GFRs higher, risking overdose. The FDA and NCI recommend capping the GFR at 125 mL/min, giving a maximum dose of 150 × AUC (900 mg at AUC 6, 750 mg at AUC 5).
Which GFR should be used — measured, Cockcroft-Gault or eGFR?
Calvert used measured GFR (⁵¹Cr-EDTA). In practice Cockcroft-Gault with actual or adjusted weight is common; some centers use a measured GFR or a BSA-de-indexed eGFR. Use the method your protocol specifies, especially in obese or frail patients.
What target AUC is used for carboplatin?
It depends on the regimen: commonly AUC 5–6 every 3 weeks (with paclitaxel or etoposide), AUC 2 weekly with concurrent radiation, and AUC 4–5 in previously treated patients. The oncologist sets the target.
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Educational calculation for health professionals only, not medical advice or a prescription. Check every dose against the current product label, local protocols and a pharmacist, and adjust it for the individual patient.