Oncology Pharmacy & Clinical Pharmacokinetics
Calvert Carboplatin AUC & Capped GFR Dose Formula
Calculate Total Carboplatin Dose (mg, NOT mg/m^2!) via A.H. Calvert’s Formula Target_AUC * (MIN(125, GFR) + 25), Pharmacy Vial Volume (mL), and Overdose Milligrams Prevented by the FDA/CTEP 125 mL/min GFR Cap.
Enforce the FDA 125 mL/min GFR cap—and never multiply Calvert carboplatin mg by BSA!
Carboplatin is eliminated predominantly by glomerular filtration, so A. Hilary Calvert et al. (1989, Journal of Clinical Oncology) replaced crude Body Surface Area (BSA) dosing with Pharmacokinetic Area-Under-the-Curve (AUC, mg/mL*min) dosing: Total_Dose_mg = Target_AUC * (GFR_mL_min + 25), where +25 mL/min accounts for non-renal tissue clearance! Oncology pharmacy verification checklists guard against two potentially fatal errors: (1) Calvert outputs TOTAL milligrams (never multiply again by patient BSA m^2!); and (2) when standardized IDMS enzymatic assays report artificially low serum creatinine in frail/cachectic patients, Cockcroft-Gault can overestimate CrCl above 150 mL/min—so FDA/NCI CTEP safety guidance caps GFR at 125 mL/min: Capped_GFR = MIN(125, Estimated_GFR), capping maximum AUC 6 dose at 6 * (125 + 25) = 900 mg!
Verify in a clinical oncology dual-pharmacist check sheet—Target_AUC = 6.0 mg/mL*min (B2), Estimated_Patient_GFR = 95 mL/min (B3 -> FDA Capped GFR = 95 mL/min in E2), and Stock_Vial_Concentration = 10 mg/mL (B4): Total Carboplatin Dose is 6 * (95 + 25) = 720.00 mg (E3); Pharmacy Draw Volume is 720 / 10 = 72.00 mL (E4); and Uncapped Overdose Prevented is 0.00 mg (E5)! Test a frail patient with apparent CrCl B3 = 155 mL/min: Capped GFR locks at 125 mL/min, Dose caps at 900.00 mg, preventing a 180.00 mg toxic overdose!
| Calvert Oncology Metric (Target AUC=6, GFR=95 mL/min, 10 mg/mL Stock Vial) | Formula | Verified Output |
|---|---|---|
| FDA / NCI Capped GFR (mL/min) | MIN(125, Estimated_GFR_mL_min) | 95 mL/min (125 Cap @ GFR=155) |
| Total Carboplatin Dose (mg) | Target_AUC * (Capped_GFR + 25) | 720.00 mg (900.00 mg Max @ AUC 6) |
| Infusion Draw Volume (mL) | Total_Dose_mg / Vial_Conc_mg_mL | 72.00 mL |
| Overdose Avoided by 125 Cap (mg) | MAX(0, Target_AUC * (GFR - 125)) | 0.00 mg (180.00 mg Saved @ 155!) |
FDA-Capped Calvert Carboplatin Total Dose (mg) Formula
Validate plausible oncology Target_AUC (1 <= AUC <= 10), strictly positive GFR > 0, and positive stock concentration > 0!
=LET(au_c, B2, gf_r, B3, cn_v, B4, IF(OR(au_c < 1, au_c > 10, gf_r <= 0, cn_v <= 0), "Invalid Oncology Dosing Input", LET(gf_c, MIN(125, gf_r), ROUND(au_c * (gf_c + 25), 2))))FDA 125 mL/min Ceiling Guard Verification (Set GFR = 155 mL/min)
Raise Estimated_GFR B3 to 155 mL/min: E2 clamps at 125, Total Dose E3 caps at 900.00 mg, and E5 logs 180.00 mg of carboplatin toxicity avoided!
=IF(ISTEXT(E3), E3, ROUND(MAX(0, B2 * (B3 - 125)), 2))Try the example
Use the original values or change them to test your understanding.