Carboplatin Order Verification: A Weight and Creatinine That No Longer Match the Patient

Do not start either drug. Hold both and escalate to the prescriber now.

Rationale:

• Carboplatin was dosed using stale data. Calvert dosing is AUC × (GFR + 25); the GFR input must reflect today, not three months ago. A creatinine that has doubled means the mixed bag almost certainly overstates the dose.
• The patient has an active problem that is itself an exclusion: two days of vomiting, tachycardia, and rising creatinine suggest volume depletion and possible acute kidney injury, plus NSAID exposure. Infusing a platinum now adds nephrotoxicity to an injured kidney.
• Thrombocytopenia matters here specifically: platelets of 92,000/µL at cycle 4 warrant a prescriber conversation before a myelosuppressive platinum, even though your protocol may not mandate a hold.
• Do not let 'it's already mixed' drive the decision. Wasted drug is a cost event; a wrong dose in a patient with AKI is a harm event. Say this out loud if pressured.
• Escalation and documentation: contact the prescriber, state the specific discrepancy (weight, creatinine, platelets), document the hold, the time, and the response, and file an incident/verification note per policy.

Show the arithmetic so the prescriber can act on it, not just hear 'I have a concern.'

1. Cockcroft-Gault on today's data (female, age 52, 74.2 kg, Cr 1.5):

• (140 − 52) × 74.2 ÷ (72 × 1.5) = 6,530 ÷ 108 ≈ 60.5 mL/min, × 0.85 ≈ 51 mL/min.

1. Same formula on baseline data (68 kg, Cr 0.7): ≈ 101 mL/min.
2. Calvert at AUC 5: today ≈ 5 × (51 + 25) = ~380 mg; as mixed ≈ 5 × (101 + 25) = ~630 mg. The hanging bag is roughly 65% higher than the patient's current renal function supports.
3. Flag the caveat rather than pretend certainty: the 6.2 kg gained is largely ascites and edema, not lean mass, and ascites/third-spacing can make a creatinine look better than the true GFR. If the team wants precision, a measured or cystatin-C-based GFR is more defensible than any estimating equation here - say so.
4. Paclitaxel is not the dose problem but is still on hold: it is hepatically cleared, so the renal change is less relevant, but you do not start half a regimen while the plan is being re-decided. Also confirm taxane-before-platinum sequencing per protocol if the cycle proceeds later today or tomorrow.
5. Propose the concrete next step: rehydrate, hold the NSAID, recheck creatinine and electrolytes, evaluate for obstruction or platinum-related injury, and re-dose carboplatin once the creatinine has stabilized.

Complete the picture before you accept a re-dosed order.

• Cause of the AKI: volume depletion from vomiting, NSAID use, urinary obstruction from pelvic disease, or platinum tubular injury. Obstruction needs imaging, not just hydration. This is the finding most likely to change the plan.
• Hypersensitivity history: carboplatin reactions cluster around cycle 6 and beyond but can occur earlier; ask about prior reactions, flushing, back pain during infusion, and any ER visit after a prior cycle. A prior reaction converts this into a desensitization or substitution discussion.
• Neurotoxicity: cumulative paclitaxel neuropathy - ask about numbness, buttoning, tripping, and falls. Grade 2 or worse prompts a dose or schedule discussion independent of the renal issue.
• Edema/ascites trend and weight trajectory: helps distinguish third-spacing from true weight gain, which matters for BSA-based drugs.
• Infection and performance status: afebrile with a normal ANC is reassuring, but vomiting plus tachycardia warrants a reassessment of whether she can tolerate treatment this week at all.
• Patient preference: she may prefer a week's delay with hydration over a dose reduction - ask rather than assume.

What would change the plan: new fever, a positive urine or blood culture, imaging showing obstruction, or a further creatinine rise - any of these converts this from 'delay and re-dose' to 'admit and work up.'