Phenazopyridine is used for the symptomatic relief of pain, burning, urgency, frequency, and other discomforts resulting from irritation of the lower urinary tract mucosa caused by infection, trauma, surgery, endoscopic procedures, or the passage of sounds or catheters. The use of phenazopyridine for relief of symptoms should not delay definitive diagnosis and treatment of causative conditions. The drug is not a substitute for specific surgery or antimicrobial therapy. Phenazopyridine also may be used for self-medication for the symptomatic relief of minor pain, urgency, frequency, and burning on urination.
Combinations of phenazopyridine hydrochloride with sulfonamides are commercially available for the initial treatment of uncomplicated urinary tract infections caused by susceptible organisms when relief of symptoms of pain, burning, or urgency is needed during the first 2 days of therapy. There is a lack of evidence that combinations of phenazopyridine hydrochloride with sulfonamides provide greater benefit than a sulfonamide alone after 2 days, and treatment beyond 2 days should only be continued with a sulfonamide alone.
Dosage and Administration
Phenazopyridine hydrochloride is administered orally after meals.
The usual adult dosage of phenazopyridine hydrochloride is 200 mg 3 times daily. Children may receive 12 mg/kg daily, given in 3 divided doses. The drug should be discontinued when pain and discomfort are relieved, usually after 3-15 days of phenazopyridine therapy. Treatment with combination preparations containing phenazopyridine hydrochloride and a sulfonamide should not exceed 2 days. Treatment beyond 2 days should only be continued with a sulfonamide alone. (See Uses.)
For self-medication in adults, the manufacturer recommends a phenazopyridine hydrochloride dosage of 190 mg 3 times daily for up to 2 days. If symptoms persist for longer than 2 days, a clinician should be consulted.
Phenazopyridine therapy has occasionally been associated with headache, vertigo, rash, pruritus, and mild GI disturbances. Rarely, methemoglobinemia, hemolytic anemia, skin pigmentation, and transient acute renal failure have been reported, usually in association with high dosage or prolonged therapy or acute overdosage, or with usual doses in patients with impaired renal function. A few cases of jaundice and hepatitis have occurred, probably caused by hypersensitivity. An anaphylactoid-like reaction also has been reported. Rarely, phenazopyridine has precipitated in the urine to form renal stones. Staining of contact lenses also has occurred in patients receiving the drug.
Precautions and Contraindications
The patient should be advised that phenazopyridine produces an orange to red color in the urine and may stain fabric; stains can be removed by soaking fabric in a 0.25% solution of sodium dithionate or sodium hydrosulfite.
Patients receiving phenazopyridine for self-medication should be advised to discontinue the drug and consult a clinician if pain and discomfort persist for longer than 2 days.
Phenazopyridine is contraindicated in patients with glomerulonephritis, severe hepatitis, uremia, pyelonephritis during pregnancy, or impaired renal function. A yellowish color of the skin or sclerae may indicate accumulation of phenazopyridine resulting from renal impairment, and necessitates discontinuance of the drug.
Animal studies have shown phenazopyridine to be a possible carcinogen, but the risk to humans in short-term therapy is believed to be negligible.
The pharmacokinetic properties of phenazopyridine have not been determined.
Trace amounts of phenazopyridine are believed to cross the placenta and to enter the CSF. It is not known if phenazopyridine is distributed into milk.
Metabolism of phenazopyridine probably occurs in the liver and other body tissues, but metabolites have not been identified. Phenazopyridine is rapidly excreted by the kidneys, with as much as 65% of an oral dose being excreted unchanged in urine. In one study in healthy individuals, maximum urinary excretion of phenazopyridine occurred within 5-6 hours after an oral dose, and the average time of total excretion of the drug was 20.4 hours. Small amounts of phenazopyridine were excreted in feces.