WCN26-4880 Combined Cystatin C– and Creatinine-Based Estimated Glomerular Filtration Rate for Colistin Dosing to Prevent Acute Kidney Injury: Preliminary Results of the COLD-PrevAKI Randomized Controlled Trial

Introduction:Acyclovir is an antiviral drug that is excreted by the kidneys.It can cause central nervous system (CNS) disorders and acute kidney injury (AKI) in elderly patients or patients with renal dysfunction.The main mechanism is accumulation of the drug and its metabolite (9-Carboxymethoxymethylguanine: CMMG).We report 5 cases that improved with hemodialysis.Methods: eCASE SERIES: Case 1: A 59-year-old female (47.8kg,BMI 19.5 kg/m2), with normal baseline renal function.Prescribed valaciclovir 3000 mg/day for herpes zoster.Day 4: disturbance of consciousness.Admission: Cre 7.72 mg/dL, eGFR 5 mL/min/1.73m2.Treated with intermittent hemodialysis (iHD) (4 hours/session) for 3 consecutive days.Consciousness improved rapidly; weaned after 5 sessions.Discharge: Cre 0.74 mg/dL, eGFR 62 mL/min/1.73m2(14-day hospitalization).Case 2: A 75-year-old female (42.6kg,BMI 17.5 kg/m2), baseline Cre 0.54 mg/dL, eGFR 83 mL/min/1.73m2;comorbid scleroderma, taking loxoprofen (NSAID).Prescribed valaciclovir 3000 mg/day.Day 3: disturbance of consciousness.Admission: Cre 5.26 mg/dL, eGFR 7 mL/ min/1.73m2.Treated with continuous hemodiafiltration (CHDF), followed by iHD (4 hours/session) on days 2, 3, and 5. Consciousness improved day 3; weaned day 5. Discharge: Cre 0.98 mg/dL, eGFR 42 mL/min/1.73m2(14-day hospitalization).Case 3: A 84-year-old female (53.7kg,BMI 25.0 kg/m2), baseline Cre 1.59 mg/dL, eGFR 24 mL/min/1.73m2;comorbidities (HTN, DM, AF), taking RAS inhibitor, SGLT2 inhibitor, and diuretics.Prescribed valaciclovir 1000 mg/day for approx. 1 month.Developed disturbance of consciousness.Admission: Cre 4.61 mg/dL, eGFR 8 mL/min/1.73m2.Treated with CHDF for 3 days.Consciousness improved the next day.Subsequently required CHDF again for heart failure.Discharge: Cre 0.93 mg/dL, eGFR 44 mL/min/1.73m2(30-day hospitalization).Case 4: A 89-year-old female (45.1kg,BMI 19.3 kg/m2), baseline Cre 0.70 mg/dL, eGFR 50 mL/min/1.73m2;comorbid RA, taking RAS inhibitor and NSAID.Prescribed valaciclovir 3000 mg/day.Day 4: disturbance of consciousness.Admission: Cre 4.2 mg/dL, eGFR 8 mL/ min/1.73m2.Transferred to our hospital.Treated with iHD (4 hours/ session) for 3 consecutive days.Consciousness improved day 2; weaned after 3 sessions.Transferred back to referring hospital (Cre 1.11 mg/dL, eGFR 35 mL/min/1.73m2)(13-day hospitalization).Case 5: A 90-year-old female (42.3kg,BMI 19.3 kg/m2), baseline Cre 0.64 mg/dL, eGFR 64 mL/min/1.73m2;comorbid HTN, taking betablocker and NSAID.Prescribed valaciclovir 3000 mg/day.Day 6: disturbance of consciousness.Admission: Cre 5.43 mg/dL, eGFR 6 mL/ min/1.73m2.Treated with iHD (3 hours/session) for 3 consecutive days.Consciousness improved rapidly; weaned after 4 sessions.Discharge: Cre 0.59 mg/dL, eGFR 70 mL/min/1.73m2(16-day hospitalization).Results: Acute blood purification therapy improved disturbance of consciousness and renal function in all cases.Conclusion: Valaciclovir-induced nephropathy/encephalopathy is common in elderly women; risk is increased by concomitant NSAIDs and RAS inhibitors.Long-term administration also poses an accumulation risk.Some cases had normal baseline renal function, but low BMI may suggest lower true GFR.Careful consideration of indication, dosage, and duration is required.Valaciclovir (225 Da, low protein binding, Vd 0.6 L/ kg) is easily removable by HD (45% removed in 3h).Blood purification therapy can improve these toxicities by removing the drug.I have no potential conflict of interest to disclose.I used generative AI and AI-assisted technologies in the writing process.During the preparation of this work the author used Gemini in order to translate and improve the fluency of English .