Carboplatin dosing using the Calvert formula includes which parameter?

• A. GFR plus 25
• B. Body surface area
• C. Body weight
• D. Median renal clearance

Answer: (A)

Carboplatin dosing is based on achieving a specific drug exposure, expressed as the target area under the curve (AUC). The Calvert formula calculates the dose as Dose = Target AUC × (GFR + 25). The parameter included is GFR plus 25, where GFR represents the kidney’s filtering capacity to clear the drug, and the constant 25 accounts for non-renal (basically non-urinary) clearance. Because carboplatin is mainly eliminated by the kidneys, adjusting the dose to match the patient’s GFR helps maintain a consistent systemic exposure. If kidney function drops (lower GFR), the required dose decreases to keep the AUC at the target level.

Body surface area, body weight, or a fixed median renal clearance aren’t part of this dosing approach, so they don’t determine the Calvert dose.