May 25, 2017
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Discontinued Warning IconPlease Note: This Brand Name drug is no longer available in the US.
(Generic versions may still be available.)

How Supplied


Acute, recurrent or chronic urinary tract infections (primarily pyelonephritis, pyelitis and cystitis) due to susceptible organisms (usually E. coli, Klebsiella-Enterobacter, staphylococcus, Proteus mirabilis and, less frequently, Proteus vulgaris) in the absence of obstructive uropathy or foreign bodies.

Meningococcal meningitis prophylaxis when sulfonamide-sensitive group A strains are known to prevail in family groups or larger closed populations. (The prophylactic usefulness of sulfonamides when group B or C infections are prevalent has not been proven and in closed population groups may be harmful.)

Acute otitis media due to Haemophilus influenzae when used concomitantly with adequate doses of penicillin.

Trachoma. Inclusion conjunctivitis. Nocardiosis. Chancroid. Toxoplasmosis as adjunctive therapy with pyrimethamine. Malaria due to chloroquine-resistant strains of Plasmodium falciparum, when used as adjunctive therapy.

Important Note: In vitro sulfonamide susceptibility tests are not always reliable. The test must be carefully coordinated with bacteriologic and clinical response. When the patient is already taking sulfonamides, follow-up cultures should have aminobenzoic acid added to the culture media.

Currently, the increasing frequency of resistant organisms is a limitation of the usefulness of antibacterial agents including the sulfonamides, especially in the treatment of chronic and recurrent urinary tract infections.

Wide variation in blood concentrations may result with identical doses. Blood concentrations should be measured in patients receiving sulfonamides for serious infections. Free sulfonamide blood concentrations of 5 to 15 mg/100 mL may be considered therapeutically effective for most infections, with blood concentrations of 12 to 15 mg/100 mL optimal for serious infections; 20 mg/100 mL should be the maximum total sulfonamide concentration, since adverse reactions occur more frequently above this concentration.


Systemic sulfonamides are contraindicated in pediatric patients under 2 months of age, except in the treatment of congenital toxoplasmosis as adjunctive therapy with pyrimethamine.

The usual dosage schedules are as follows:

Dosage Schedules
Pediatric Patients
Weight of Pediatric Patients
(2 Months or Older)
Initial Dose
(50 to 60 mg/kg)
Dose Morning and Evening
 Daily Thereafter (25 to 30 mg/kg)
20 lbs 1 tablet
(0.5 gm)
½ tablet
(0.25 gm)
40 lbs 2 tablets
(1 gm)
1 tablet
(0.5 gm)
60 lbs 3 tablets
(1.5 gm)
1½ tablets
(0.75 gm)
80 lbs 4 tablets
(2 gm)
2 tablets
(1 gm)
The maximum dose for pediatric patients should not exceed 75 mg/kg/24 hours.
Mild to
Moderate Infections
4 tablets
(2 gm)
2 tablets
(1 gm)

Severe Infections: 4 tablets (2 g) initially, followed by 2 tablets (1 g) three times daily thereafter.

Patients with impaired renal function (creatinine clearance below 20 to 30 mL/min) require decreased dosage adjustment.


Tablets (pale green, scored), containing 0.5 g sulfamethoxazole † bottles of 100 (NDC 0004-0010-01). Imprint on tablets: GANTANOL (sulfamethoxazole) ® ROCHE.

This monograph has been modified to include the generic and brand name in many instances.

Last reviewed on RxList: 12/25/2016

How Supplied

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