Acute Renal Failure and Jaundice without Methemoglobinemia in a Patient with Phenazopyridine Overdose: Case Report and Review of the Literature

Phenazopyridine is a commonly used urinary analgesic available throughout the United States. Ingestion of large quantities can lead to methemoglobinemia, hemolytic anemia, jaundice, and acute renal failure. We report a case of a 78-year-old male with previously normal renal function who developed acute renal failure and jaundice without methemoglobinemia or hyperbilirubinemia after taking nearly 8？g of phenazopyridine over the course of 4 days. Initially presenting with oliguria, the urine output began to increase by day 2 of his admission, and the creatinine peaked 11 days after he began taking phenazopyridine, and he was discharged safely soon after. To our knowledge, this is the first such case of renal failure and jaundice without methemoglobinemia or hemolytic anemia in an adult patient with normal renal function. 1. Introduction Phenazopyridine is a commonly prescribed urinary analgesic which has been in use since the 1920s [1]. Its use is associated with gastrointestinal discomfort and orange discoloration of urine [2]. Rarely, patients have developed pigment stones due to the red azo dye which is part of the drug’s formulation [1]. In large doses, phenazopyridine has been reported to cause renal failure, methemoglobinemia, skin pigmentation, and hemolytic anemia [2–7]. These findings often occur together, although isolated renal failure has been reported in pediatric patients and in patients with underlying renal disease [4, 7, 8]. We report a case of anuric renal failure and jaundice due to phenazopyridine without hyperbilirubinemia, methemoglobinemia, or hemolytic anemia in a patient without underlying renal disease. Previous case reports of phenazopyridine-associated kidney injury have either been in pediatric patients or in patients with underlying renal disease; to our knowledge, this is the first such case in a patient with normal renal function [3]. 2. Case Report A 78-year-old male physician with no prior renal disease presented to the emergency department with anuria. Five days prior to presentation, he had developed dysuria and urinary frequency and started himself on levofloxacin and phenazopyridine. Over the course of four days, he had taken 39 200？mg tabs of phenazopyridine (approximately 7.8？g). One day prior to admission, he noted that his urine output had ceased despite increased oral intake and decided to present to the emergency department. On presentation, the patient was hypotensive to 70/40 with a heart rate of 91？bpm but had no orthostatic symptoms. He received four liters of normal saline with no improvement in urine