phenazopyridine hydrochloride
Azo-Standard, Baridium, Geridium, Phenazo ◆, Prodium, Pyridiate, Pyridium, Pyridium Plus, Urogesic

Available forms
Available by prescription only
Tablets: 97.2 mg, 150 mg, 200 mg
Tablets: 95 mg, 100 mg

Indications and dosages
 Pain with urinary tract irritation or infection. Adults: 200 mg P.O. t.i.d. Give drug after meals.

Pharmacodynamics
Analgesic action: Mechanism unknown. Has a local anesthetic effect on urinary tract mucosa.

Pharmacokinetics
Absorption: No information available.
Distribution: Traces thought to enter CSF and cross the placental barrier.
Metabolism: Metabolized in liver.
Excretion: Excreted by kidneys; 65% excreted unchanged in urine. Totally excreted on average in 20.4 hours.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug and in those with glomerulonephritis, severe hepatitis, uremia, pyelonephritis during pregnancy, or renal insufficiency.

Interactions
None reported.

Adverse reactions
CNS: headache.
GI: nausea, GI disturbances.
Hematologic: hemolytic anemia, methemoglobinemia.
Skin: rash, pruritus.
Other: anaphylactoid reactions.

Effects on lab test results
• May decrease hemoglobin and hematocrit.

Overdose and treatment
Toxicity may cause methemoglobinemia (most obvious as cyanosis), along with renal and hepatic impairment and failure.
 To treat overdose, empty stomach immediately by inducing emesis with ipecac syrup or by gastric lavage. Administer methylene blue, 1 to 2 mg/kg I.V., or 100 to 200 mg ascorbic acid P.O. to reverse methemoglobinemia. Provide symptomatic and supportive measures (respiratory support and correction of fluid and electrolyte imbalances). Monitor laboratory parameters and vital signs closely. Contact local or regional poison information center for specific instructions.

Special considerations
• Drug colors urine red or orange; may stain fabrics.
• Use only as an analgesic.
• May be used with an antibiotic to treat urinary tract infections.
• Discontinue drug in 2 days with concurrent antibiotic use.
• Drug may alter results of Diastix, Chemstrip uG, glucose enzymatic test strip, Acetest, and Ketostix. Clinitest should be used to obtain accurate urine glucose test results. Drug may also interfere with Ehrlich’s test for urine urobilinogen; phenolsulfonphthalein excretion tests of kidney function; sulfobromophthalein excretion tests of liver function; and urine tests for protein, corticosteroids, or bilirubin.
• Administer with food or fluids to reduce GI upset.
• Evaluate response to therapy; assess urinary function, such as output, complaints of burning, pain, and frequency. Monitor vital signs, especially temperature. Encourage patient to force fluids (if not contraindicated). Monitor intake and output.
Breast-feeding patients
• It isn’t known if drug appears in breast milk. Safe use in breast-feeding women hasn’t been established.
Geriatric patients
• Use cautiously in elderly patients because of possible decreased renal function.

Patient education
• Instruct patient in measures to prevent urinary tract infection.
• Caution patient that drug colors urine red or orange and may stain clothing.
• Tell patient that stains on clothing may be removed with a 0.25% solution of sodium dithionite or hydrosulfite.
• Advise patient to take missed dose as soon as possible but not to double doses.
• Instruct patient to report symptoms that worsen or don’t resolve.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use