Urinary Analgesic (phenazopyridine) Disease Interactions

Patients with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency may be at increased risk for phenazopyridine-induced methemoglobinemia and hemolytic anemia. These conditions have occurred rarely in other patients, except due to acute phenazopyridine overdose or impaired renal function. Therapy with phenazopyridine should be administered cautiously in patients with G-6-PD deficiency.

The use of phenazopyridine is contraindicated in patients with severe hepatitis. Rare cases of hepatotoxicity have been associated with phenazopyridine, usually at overdose levels. Hypersensitivity hepatitis has also been reported. Therapy with phenazopyridine should be administered cautiously in patients with impaired hepatic function.

The use of phenazopyridine is contraindicated in patients with impaired renal function. Phenazopyridine is primarily eliminated unchanged by the kidney and may accumulate to toxic levels during prolonged administration in such patients. Reported cases of toxicity due to overdosage have resulted in acute renal failure and methemoglobinemia. Likewise, administration of phenazopyridine to patients with preexisting renal failure has led to methemoglobinemia and hemolytic anemia. Phenazopyridine toxicity may be associated with a yellowish tinge of the skin or sclera.