Abstract: SA-PO1115
Pharmacologic Interaction in an Elderly Patient with Kidney Dysfunction: Acetazolamide and Aspirin in Focus
Session Information
- Geriatric Nephrology
November 08, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Geriatric Nephrology
- 1300 Geriatric Nephrology
Authors
- Ahmed, Zahoor, Jefferson Einstein Philadelphia Hospital, Philadelphia, Pennsylvania, United States
- Kanwal, Sidra, Avicenna Medical College, Lahore, Punjab, Pakistan
- Agboola, Adedamola, NHS England, Redditch, England, United Kingdom
- Samreen, Iqra, Parkview Health, Fort Wayne, Indiana, United States
- Mohamed, Khalid H., NHS England, Redditch, England, United Kingdom
Introduction
Polypharmacy and multimorbidity, including chronic kidney disease (CKD), are prevalent among geriatric patients, significantly increasing the risk of adverse drug interactions. This case highlights a rare interaction between acetazolamide and aspirin in a patient with CKD, leading to severe metabolic acidosis and hyperammonemia.
Case Description
A 73-year-old male with a history of CAD, HFrEF, DM, CKD stage 3, chronic anxiety, and prior stroke was admitted for acute angle-closure glaucoma. He was managed with brimonidine, brinzolamide, timolol, and oral acetazolamide 250 mg twice daily, and was discharged. He was concurrently on aspirin (81mg), furosemide, empagliflozin, atorvastatin, and sertraline. Four days after starting acetazolamide, he presented with confusion, agitation, and lethargy, raising concerns of acute encephalopathy. He was hemodynamically stable with no neurologic deficit. Laboratory workup revealed mild leukocytosis (12,500/ul), elevated creatinine (2.9 mg/dL), and eGFR of 33 ml/min. Urine analysis was unremarkable. LFT and TSH were normal. CT brain and chest x-ray were negative for acute insult. Infectious workup was negative. After ruling out possible etiologies, acetazolamide toxicity was suspected due to concurrent use of aspirin, AKI on CKD, and dehydration. Further workup showed hyperchloremic metabolic acidosis (pH: 7.21, HCO3: 4.8 mmol/l, Cl: 122 mmol/l) and mildly elevated blood ammonia level (97 umol/l), suggestive of acetazolamide toxicity. Acetazolamide was discontinued, and hydration therapy was initiated. His renal function and mental status gradually normalized.
Discussion
Interaction between acetazolamide and aspirin in elderly patients with CKD is rarely reported. Aspirin inhibits plasma protein binding, increases acetazolamide’s unbound plasma concentration, and impairs its clearance through organic anion transport pathway, exacerbating metabolic acidosis and hyperammonemia. Increased acetazolamide plasma concentration causes hyperammonemia due to excessive carbonic anhydrase inhibition, disrupting urea synthesis. In our case, this toxicity was further enhanced by dehydration. Although rare, there is no warning sign on EMR for these medications to commence in CKD patients concurrently. Recognizing such interactions is critical to improving medication safety in older adults with CKD.