Acute methemoglobinemia and hemolytic anemia with phenazopyridine: possible relation to acute renal failure.

An 18-year-old woman with no prior history of renal or hematologic dysfunction developed severe, acute methemoglobinemia after an overdose of phenazopyridine hydrochloride (Pyridium). The methemoglobinemia was reversed acutely with methylene blue, and during the course of ten days, the patient developed a hemolytic anemia with "bite cells" and acute renal failure. The patient recovered fully with conservative management. Several putative pathophysiologic explanations for the development of methemoglobinemia, hemolytic anemia, and renal failure following oxidative stress are considered and include a direct toxic effect on the renal tubules or methemoglobin-caused damage. Renal failure as a complication of phenazopyridine-related methemoglobinemia and hemolytic anemia should be borne in mind in cases of overdosage with this common drug.

Protracted methemoglobinemia after phenazopyridine overdose in an infant.

Acquired methemoglobinemia may be produced by the ingestion or absorption of certain chemicals and xenobiotics. A case of methemoglobinemia in an 8.5-month old infant who ingested approximately 227 mg/kg of phenazopyridine is presented. Although this adverse event is often reversed with a single dose of methylene blue, this patient required three doses of methylene blue (1 mg/kg) over a 25-hour period. It is suggested that the need for repeated doses of methylene blue in this case was not only related to the large dose of phenazopyridine, but also its metabolites (i.e., aniline), which have the potential to produce methemoglobinemia. This case illustrates the need for close observation and serial monitoring of methemoglobin levels in patients who are at increased risk for the development of protracted methemoglobinemia. Integration of knowledge of developmental pharmacology, drug metabolism, and pharmacodynamic properties are critical determinants in the evaluation and treatment of patients with drug-induced methemoglobinemia.

Methemoglobinemia due to ingestion of at most three pills of pyridium in a 2-year-old: case report and review.

Pyridium (phenazopyridine HCl) is a commonly prescribed medication in the treatment of urinary tract infections and is known to cause methemoglobinemia in excessive doses. We report the case of a 2-year-old child who ingested a maximum of three 200-mg tablets (approximately 50 mg/kg) of pyridium and yet developed cyanosis and methemoglobinemia (29.1%), resulting in methylene blue therapy. We urge physicians to consider a period of observation (4-6 h) or to obtain methemoglobin levels in children who ingest even a small number of pyridium tablets because this can represent a toxic dose in a small child.

Acute renal failure due to phenazopyridine (Pyridium) overdose: case report and review of the literature.

Phenazopyridine (Pyridium) is a commonly used urinary tract analgesic. It has been associated with yellow skin discoloration, hemolytic anemia, methemoglobinemia, and acute renal failure, especially in patients with preexisting kidney disease. We report a 17-year-old female with vertically transmitted human immunodeficiency virus (HIV) infection, presenting with acute renal failure and methemoglobinemia following a suicidal attempt with a single 1,200 mg ingestion of Pyridium. She had no prior evidence of HIV nephropathy. The patient had a progressive nonoliguric renal failure on the 3rd day following the ingestion. She was treated with N-acetylcysteine, intravenous carnitine, and alkalinization of the urine. Her kidney biopsy revealed acute tubular necrosis with no glomerular changes. After 7 days of conservative management, she was discharged home with normal kidney function. To our knowledge, this is the second smallest amount of Pyridium overdose resulting in acute renal failure with no previous history of kidney disease.

[Acute renal failure caused by phenazopyridine]. / Falla renal aguda por fenazopiridina.

A 27 years old woman was admitted due to abdominal cramps, jaundice and oligoanuria, starting 48 hours after eating Chinese food. Hepatic biochemical tests, abdominal ultrasound and retrograde pyelography were normal. The urine was intensely orange colored and microscopic analysis was normal. The serum creatinine and urea nitrogen on admission were 4.59 and 42.5 mg/dl and rose to 13.5 and 72.4 mg/dl, respectively, at the 6th hospital day. Oliguria lasted only 48 hours. Dialysis was not used, since the patient was in good general condition and uremic symptoms were absent. On the 7th day, azotemia began to subside and at the 14th day, serum creatinine was 1.0 mg/dl. Before hospital discharge, she confessed the ingestion of 2.000 mg of phenazopyridine, during a nervous breakdown, aiming to sleep deeply. Remarkable was the persistence of the orange color of her urine during several days and the dissociation between the rate of increase of serum creatinine with respect to urea nitrogen. This is an unusual case of acute renal failure caused by an overdose of a drug, commonly prescribed for urinary tract infections.

Life-threatening Pyridium Plus intoxication: a case report.

A 16-month-old male presented with an overdose of Pyridium Plus--a combination anticholinergic, azo dye, and barbiturate--resulting in seizures, coma, and methemoglobinemia. This case report reviews the treatment of methemoglobinemia with methylene blue, activated charcoal, and exchange transfusion. Additionally, the role of the pulse oximeter is addressed when methemoglobinemia exists and is treated with methylene blue.

Methemoglobinemia from overdose of phenazopyridine hydrochloride.

A case of severe methemoglobinemia and hemolytic anemia following ingestion of 5.6 gm of phenazopyridine with suicidal intent by a 16-year-old woman was successfully treated with intravenous methylene blue. Methemoglobinemia was suspected in this patient because of her intense central cyanosis, chocolate-colored blood, and minimal dyspnea. The patient's peripheral blood smear exhibited "bite cells." To the best of our knowledge, this is only the third such case reported in the literature. The pathophysiology, diagnosis, and therapy are reviewed.

Nephrotoxicity of phenazopyridine.

A young man developed reversible acute renal failure after a large overdose of phenazopyridine. The renal failure was treated by peritoneal dialysis. Analysis of blood and urine samples failed to demonstrate the parent drug but a metabolite with similar ultraviolet absorption was detected. No parent drug or metabolites were detected in the peritoneal dialysate.

Life-threatening Pyridium Plus intoxication: a case report.

A 16-month-old male presents with an overdose of Pyridium Plus, a combination anticholinergic, azo dye, and barbiturate, resulting in seizures, coma, and methemoglobinemia. This case report reviews the treatment of methemoglobinemia with methylene blue, activated charcoal, and exchange transfusion. Additionally, the role of the pulse oximeter is addressed when methemoglobinemia exists and is treated with methylene blue.

Methemoglobinemia, muscle damage and renal failure complicating phenazopyridine overdose.

A 19-year-old woman with no history of renal or hematologic dysfunction developed methemoglobinemia, muscle damage, rhabdomyolysis and severe acute renal failure after an overdose of phenazopyridine hydrochloride (pyridium). The methemoglobinemia reversed after 24 h, but the patient remained oliguric, with myalgia and increased muscle enzymes. The patient received supportive treatment and recovered completely after 3 weeks. Since phenazopyridine is a commonly used drug, the physician should be alert to these possible severe complications.

Falla renal aguda por fenazopiridina / Acute renal failure caused by phenazopyridine

A 27 years old woman was admitted due to abdominal cramps, jaundice and oligoanuria, starting 48 hours after eating Chinese food. Hepatic biochemical tests, abdominal ultrasound and retrograde pyelography were normal. The urine was intensely orange colored and microscopic analysis was normal. The serum creatinine and urea nitrogen on admission were 4.59 and 42.5 mg/dl and rose to 13.5 and 72.4 mg/dl, respectively, at the 6th hospital day. Oliguria lasted only 48 hours. Dialysis was not used, since the patient was in good general condition and uremic symptoms were absent. On the 7th day, azotemia began to subside and at the 14th day, serum creatinine was 1.0 mg/dl. Before hospital discharge, she confessed the ingestion of 2.000 mg of phenazopyridine, during a nervous breakdown, aiming to sleep deeply. Remarkable was the persistence of the orange color of her urine during several days and the dissociation between the rate of increase of serum creatinine with respect to urea nitrogen. This is an unusual case of acute renal failure caused by an overdose of a drug, commonly prescribed for urinary tract infections.