Sulfonamides and Phenazopyridine (Systemic)

This monograph includes information on the following:

1) Sulfamethoxazole and Phenazopyridine 
2) Sulfisoxazole and Phenazopyridine

VA CLASSIFICATION
Primary: AM650

Commonly used brand name(s): Azo Gantanol1; Azo Gantrisin2; Azo-Sulfamethoxazole1; Azo-Sulfisoxazole2; Azo-Truxazole2; Sul-Azo2.

Note: For a listing of dosage forms and brand names by country availability, see Dosage Forms section(s).

Not commercially available in Canada.



Category:


Antibacterial-analgesic (urinary tract)—

Indications

Accepted

Urinary tract infections, bacterial (treatment)—Sulfonamide and phenazopyridine combinations are indicated in the treatment of the acute, painful phase of uncomplicated urinary tract infections caused by Escherichia coli , Klebsiella species, Enterobacter species, Proteus mirabilis , P. vulgaris , and Staphylococcus aureus . After relief of pain has been obtained, treatment should be continued with either sulfamethoxazole or sulfisoxazole alone. {01} {02}

—Not all species or strains of a particular organism may be susceptible to a specific sulfonamide.


Pharmacology/Pharmacokinetics

Sulfonamides—See Sulfonamides (Systemic).

Phenazopyridine—See Phenazopyridine (Systemic).


Precautions to Consider

Sulfonamides—See Sulfonamides (Systemic).

Phenazopyridine—See Phenazopyridine (Systemic).


Side/Adverse Effects
Sulfonamides—See Sulfonamides (Systemic).
Phenazopyridine—See Phenazopyridine (Systemic).



Patient Consultation
As an aid to patient consultation, refer to Advice for the Patient, Sulfonamides and Phenazopyridine (Systemic).

In providing consultation, consider emphasizing the following selected information (» = major clinical significance):

Before using this medication
»   Conditions affecting use, especially:
Allergies to sulfonamides, furosemide, thiazide diuretics, sulfonylureas, carbonic anhydrase inhibitors, or phenazopyridine

Pregnancy—Sulfonamides cross the placenta; use is contraindicated at term since sulfonamides may cause kernicterus





Breast-feeding—Sulfonamides are excreted in breast milk; may cause kernicterus in the nursing infant





Use in children—Use is contraindicated in children up to 12 years of age

Other medications, especially coumarin- or indandione-derivative anticoagulants, hydantoin anticonvulsants, oral antidiabetic agents, hemolytics, hepatotoxic medications, methenamine, and methotrexate
Other medical problems, especially blood dyscrasias, G6PD deficiency, hepatic function impairment, hepatitis, megaloblastic anemia due to folate deficiency, porphyria, and renal function impairment

Proper use of this medication
» Maintaining adequate fluid intake; taking with or following meals if gastrointestinal irritation occurs

» Compliance with full course of therapy

» Importance of not missing doses and taking at evenly spaced times

» Proper dosing; not giving to infants and children up to 12 years of age
Missed dose: Taking as soon as possible; not taking if almost time for next dose; not doubling doses

» Proper storage

Precautions while using this medication
Checking with physician if no improvement within a few days or if symptoms become worse

Using caution with regular toothbrushes, dental floss, and toothpicks; deferring dental work until blood counts have returned to normal; checking with physician or dentist concerning proper oral hygiene

» Possible photosensitivity reactions

» Caution if dizziness occurs

» Medication causes urine to turn reddish orange and may stain clothing

» Diabetics: May cause false urine sugar and urine ketone test results


Side/adverse effects
Reddish orange discoloration of urine may be alarming to patient although medically insignificant

Signs of potential side effects, especially blood dyscrasias, crystalluria, goiter, headache, hematuria, hemolytic anemia, hepatitis, hypersensitivity, interstitial nephritis, Lyell's syndrome, methemoglobinemia, photosensitivity, Stevens-Johnson syndrome, thyroid function disturbance, and tubular necrosis


General Dosing Information
Sulfonamides and phenazopyridine may be taken with or following meals if gastrointestinal irritation occurs.

Fluid intake should be sufficient to maintain urine output of at least 1200 to 1500 mL per day in adults.

Patients with impaired renal function may require a reduction in dose.

SULFAMETHOXAZOLE AND PHENAZOPYRIDINE


Additional Dosing Information
See also General Dosing Information.

Although sulfamethoxazole has a greater tendency than sulfisoxazole to cause crystalluria because of sulfamethoxazole's slower absorption and excretion, alkalinization of the urine is usually unnecessary.


Oral Dosage Forms

SULFAMETHOXAZOLE AND PHENAZOPYRIDINE HYDROCHLORIDE TABLETS

Usual adult and adolescent dose
Urinary tract infections, bacterial
Oral, 2 grams of sulfamethoxazole and 400 mg of phenazopyridine hydrochloride initially, then 1 gram of sulfamethoxazole and 200 mg of phenazopyridine hydrochloride every twelve hours for up to two days.


Usual pediatric dose
Urinary tract infections, bacterial
Infants and children up to 12 years of age: Use is contraindicated.

Children 12 years of age and over: See Usual adult and adolescent dose.


Strength(s) usually available
U.S.—


500 mg of sulfamethoxazole and 100 mg of phenazopyridine hydrochloride (Rx) [Azo Gantanol] [Azo-Sulfamethoxazole][Generic]

Canada—
Not commercially available.

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), in a tight, light-resistant container, unless otherwise specified by manufacturer.

Auxiliary labeling:
   • Take with a full glass of water.
   • Avoid too much sun or use of sunlamp.
   • May cause dizziness.
   • Continue medicine for full time of treatment.
   • May discolor urine.

Note: Stains on clothing may be removed with a 0.25% solution of sodium dithionate or sodium hydrosulfite.



SULFISOXAZOLE AND PHENAZOPYRIDINE


Additional Dosing Information
See also General Dosing Information.

Because of its relatively high solubility even in acid urine, the risk of crystalluria with sulfisoxazole is low and alkalinization of the urine is usually unnecessary.


Oral Dosage Forms

SULFISOXAZOLE AND PHENAZOPYRIDINE HYDROCHLORIDE TABLETS

Usual adult and adolescent dose
Urinary tract infections, bacterial
Oral, 2 to 3 grams of sulfisoxazole and 200 to 300 mg of phenazopyridine hydrochloride initially, then 1 gram of sulfisoxazole and 100 mg of phenazopyridine hydrochloride every six hours for up to two days.


Usual pediatric dose
Urinary tract infections, bacterial
Infants and children up to 12 years of age: Use is contraindicated.

Children 12 years of age and over: See Usual adult and adolescent dose.


Strength(s) usually available
U.S.—


500 mg of sulfisoxazole and 50 mg of phenazopyridine hydrochloride (Rx) [Azo Gantrisin] [Azo-Sulfisoxazole] [Azo-Truxazole] [Sul-Azo][Generic]

Canada—


500 mg of sulfisoxazole and 50 mg of phenazopyridine hydrochloride (Rx) [Azo Gantrisin]

Packaging and storage:
Store below 40 °C (104 °F), preferably between 15 and 30 °C (59 and 86 °F), in a tight, light-resistant container, unless otherwise specified by manufacturer.

Auxiliary labeling:
   • Take with a full glass of water.
   • Avoid too much sun or use of sunlamp.
   • May cause dizziness.
   • Continue medicine for full time of treatment.
   • May discolor urine.

Note: Stains on clothing may be removed with a 0.25% solution of sodium dithionate or sodium hydrosulfite.




Revised: 02/01/1993



References
  1. PDR 1988, Azo Gantanol (Roche), pp 1709-10.
  1. PDR 1988, Azo Gantrisin (Roche), p 1710.
  1. Redbook 1989, Sul-Azo (Lunsco), p 654.
  1. CPS 1988, Azo-Gantrisin (Roche), p 96.
  1. USP DI 1989, VA Medication Classification System, p 2472.
  1. Redbook 1989, Azo-Cheragan (Cenci), p 167.
  1. PDR 1989, Azo Gantanol (Roche), p 1720.
  1. Redbook 1989, Azo-Sulfamethoxazole (generic), p 167.
  1. CPS 1988, Uro Gantanol (Roche), p 975.
  1. Redbook 1989, Azo-Cheragan (Cenci), p 167.
  1. PDR 1989, Azo Gantrisin (Roche), p 1721.
  1. Redbook 1989, Azo-Sulfisoxazole (generic), p 167.
  1. Redbook 1989, Azo-Truxazole (Truxton), p 167.
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