John is a 62-year-old male admitted to the medical ICU with sepsis. He has a history of hypertension and type 2 diabetes. His current medications include cefepime 2g every 8 hours and lisinopril 20mg daily. Recent labs show serum creatinine of 1.1 mg/dL and cystatin C of 2.3 mg/L. The pharmacist calculates eGFR using Cockcroft-Gault (CG) and CKD-EPI creatinine-cystatin C (eGFRcr-cys) equations and finds a significant difference impacting cefepime dosing.

Based on the study findings, what is the most appropriate pharmacist action regarding cefepime dosing for John?

Maria is a 55-year-old female in the surgical ICU receiving vancomycin for a complicated infection. Her serum creatinine is 0.9 mg/dL, and cystatin C is elevated at 2.5 mg/L. The pharmacist notes that Cockcroft-Gault eGFR suggests normal renal function, but CKD-EPI eGFRcr-cys indicates moderate impairment.

What is the best pharmacist recommendation for vancomycin dosing in Maria based on the study and related evidence?

David is a 70-year-old male with acute kidney injury admitted to the neurological ICU. His medications include levetiracetam 500 mg twice daily and piperacillin/tazobactam 3.375 g every 6 hours. Serum creatinine is 1.3 mg/dL, cystatin C is 3.0 mg/L. The pharmacist observes a discrepancy between CG and CKD-EPI eGFRcr-cys calculations affecting dosing recommendations.

How should the pharmacist proceed with dosing adjustments for levetiracetam and piperacillin/tazobactam in this patient?