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Abbreviated List

Sulfonamide or sulphonamide is the basis of several groups of drugs. The original antibacterial sulfonamides (sometimes called sulfa drugs or sulpha drugs) are synthetic antimicrobial agents that contain the sulfonamide group. Some sulfonamides are also devoid of antibacterial activity, e.g., the anticonvulsant sultiame. The sulfonylureas and thiazide diuretics are newer drug groups based on the antibacterial sulfonamides.
Allergies to sulfonamide are common, hence medications containing sulfonamides are prescribed carefully. It is important to make a distinction between sulfa drugs and other sulfur-containing drugs and additives, such as sulfates and sulfites, which are chemically unrelated to the sulfonamide group, and do not cause the same hypersensitivity reactions seen in the sulfonamides.Because sulfonamides displace bilirubin from albumin, kernicterus (brain damage due to excess bilirubin) is an important potential side effect of sulfonamide use.

Short-acting: Sulfacetamide, Sulfadiazine, Sulfadimidine, Sulfafurazole
Intermediate-acting: Sulfadoxine, Sulfamethoxazole, Sulfamoxole
Long-acting: Sulfadimethoxine, Sulfamethoxypyridazine, Sulfametoxydiazine
Ultra long-acting: Sulfadoxine, Sulfametopyrazine
Dermatologicals: Mafenide

[Source: ]

Infectious Disease -ALL Agents (INDEX)

Antimicrobials - Infectious Disease

Aminoglycosides Ansamycins/Rifamycins Antibiotics (Other)
Anti- Fungals Anti-Herpetic Agents Anti-Influenza Agents
Anti-Malarials Carbapenems Cephalosporins
Fluoroquinolones Glycopeptides HIV (anti) Agents
Lincosamides Lipopeptides Macrolides
Monobactams Oxazolidones Penicillins
Sulfonamide antibiotics Tetracyclines Tuberculosis (anti) agents

Trimethoprim-Sulfamethoxazole (TMP-SMX) -Bactrim®

Dosing (adults): (IV): 8-10mg/kg/day divided q6-12h.
Pneumocystis Jiroveci Pneumonia: 15-20mg/kg/day in 3 or 4 divided doses.
(Oral): Urinary tract infection: 1 DS tab (160mg TMP/800mg SMX) po q12h.

Renal Dosing:
[>30 ml/min]: no change .
[15-30] 50% of usual regimen.

Alternatively: 8-10mg/kg/day divided q12h x 1-2 days, then 4-6mg/kg q24h.
[<15] not recommended by manufacturer.

Alternatively: Non PCP: 8-12 mg/kg/dose q48h (or 4-6 mg/kg/day divided q12-24h) .
PCP: 15-20 mg/kg/dose q48h (or 7-10 mg/kg/day divided q12-24h).

Hemodialysis: Not recommended by manufacturer.

Sulfamethoxazole inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA). Trimethoprim blocks the production of tetrahydrofolic acid from dihydrofolic acid by binding to and reversibly inhibiting the required enzyme, dihydrofolate reductase. Thus, sulfamethoxazole and trimethoprim blocks two consecutive steps in the biosynthesis of nucleic acids and proteins essential to many bacteria.

In vitro studies have shown that bacterial resistance develops more slowly with both sulfamethoxazole and trimethoprim in combination than with either sulfamethoxazole or trimethoprim alone.

Sulfamethoxazole and trimethoprim have been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section.

Aerobic gram-positive microorganisms:
Streptococcus pneumoniae

Aerobic gram-negative microorganisms:
Escherichia coli (including susceptible enterotoxigenic strains implicated in traveler's diarrhea)
Klebsiella species
Enterobacter species
Haemophilus influenzae
Morganella morganii
Proteus mirabilis
Proteus vulgaris
Shigella flexneri
Shigella sonnei

Other Organisms:
Pneumocystis jiroveci

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Bactrim (sulfamethoxazole and trimethoprim) tablets and other antibacterial drugs, Bactrim (sulfamethoxazole and trimethoprim) tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to empiric selection of therapy.

Urinary Tract Infections: For the treatment of urinary tract infections due to susceptible strains of the following organisms: Escherichia coli, Klebsiella species, Enterobacter species, Morganella morganii, Proteus mirabilis and Proteus vulgaris. It is recommended that initial episodes of uncomplicated urinary tract infections be treated with a single effective antibacterial agent rather than the combination.

Acute Otitis Media: For the treatment of acute otitis media in pediatric patients due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae when in the judgment of the physician sulfamethoxazole and trimethoprim offers some advantage over the use of other antimicrobial agents. To date, there are limited data on the safety of repeated use of BACTRIM in pediatric patients under two years of age. BACTRIM is not indicated for prophylactic or prolonged administration in otitis media at any age.

Acute Exacerbations of Chronic Bronchitis in Adults: For the treatment of acute exacerbations of chronic bronchitis due to susceptible strains of Streptococcus pneumoniae or Haemophilus influenzae when a physician deems that BACTRIM could offer some advantage over the use of a single antimicrobial agent.

Shigellosis: For the treatment of enteritis caused by susceptible strains of Shigella flexneri and Shigella sonnei when antibacterial therapy is indicated.

Pneumocystis jiroveci Pneumonia: For the treatment of documented Pneumocystis jiroveci pneumonia and for prophylaxis against P. jiroveci pneumonia in individuals who are immunosuppressed and considered to be at an increased risk of developing P. jiroveci pneumonia.

Traveler's Diarrhea in Adults: For the treatment of traveler's diarrhea due to susceptible strains of enterotoxigenic E. coli.

BACTRIM is contraindicated in pediatric patients less than 2 months of age.

Urinary Tract Infections and Shigellosis in Adults and Pediatric Patients, and Acute Otitis Media in Children:

Adults: The usual adult dosage in the treatment of urinary tract infections is 1 BACTRIM DS (double strength) tablet or 2 BACTRIM tablets every 12 hours for 10 to 14 days. An identical daily dosage is used for 5 days in the treatment of shigellosis.

Children: The recommended dose for children with urinary tract infections or acute otitis media is 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days. An identical daily dosage is used for 5 days in the treatment of shigellosis. The following table is a guideline for the attainment of this dosage:
Children 2 months of age or older:

Weight Dose-every 12 hours
lb kg Tablets
22 10 -
44 20 1 ss tablet
66 30 1.5 ss tablet
88 40 2 ss or 1 DS tablet
ss= single strength tablet.  DS= double strength tablet

Acute Exacerbations of Chronic Bronchitis in Adults:
The usual adult dosage in the treatment of acute exacerbations of chronic bronchitis is 1 BACTRIM DS (double strength) tablet or 2 BACTRIM tablets every 12 hours for 14 days.

Pneumocystis Jiroveci Pneumonia:
Treatment: Adults and Children:

The recommended dosage for treatment of patients with documented Pneumocystis jiroveci pneumonia is 75 to 100 mg/kg sulfamethoxazole and 15 to 20 mg/kg trimethoprim per 24 hours given in equally divided doses every 6 hours for 14 to 21 days. The following table is a guideline for the upper limit of this dosage:

Weight Dose-every 6 hours
lb kg Tablets
18 8 -
35 16 1
53 24 1.5 ss tablet
70 32 2 ss tablet or 1 DS tablet
88 40 2.5 ss tablets
106 48 3 ss tablets or 1.5 DS tablets
141 64 4 ss tablets or 2 DS tablets
176 80 5 ss tablets or 2.5 DS tablets
ss= single strength tablet.  DS= double strength tablet

For the lower limit dose (75 mg/kg sulfamethoxazole and 15 mg/kg trimethoprim per 24 hours) administer 75% of the dose in the above table.

The recommended dosage for prophylaxis in adults is 1 BACTRIM DS (double strength) tablet daily.

For children, the recommended dose is 750 mg/m2/day sulfamethoxazole with 150 mg/m2/day trimethoprim given orally in equally divided doses twice a day, on 3 consecutive days per week. The total daily dose should not exceed 1600 mg sulfamethoxazole and 320 mg trimethoprim. The following table is a guideline for the attainment of this dosage in children:

Body Surface Area Dose-every 12 hours
(m2) Tablets
0.26 -
0.53 one-half ss tablet
1.06 1 ss tablet

ss= single strength tablet.

Traveler's Diarrhea in Adults:
For the treatment of traveler's diarrhea, the usual adult dosage is 1 BACTRIM DS (double strength) tablet or 2 BACTRIM tablets every 12 hours for 5 days.

Renal Dosing:
For Patients with Impaired Renal Function: When renal function is impaired, a reduced dosage should be employed using the following table:

Clearance (mL/min)
Dosage Regimen
Above 30 Usual standard regimen
15-30 one-half the usual regimen
Below 15 Use not recommended

BACTRIM™ TABLETS are supplied as follows:

BACTRIM™ DS (double strength) TABLETS (white, oval shaped, scored) containing 160 mg trimethoprim and 800 mg sulfamethoxazole - bottles of 100 (NDC 13310-146-01) and 500 (NDC 13310-146-05). Imprint on tablets (debossed): (front) BACTRIM DS

BACTRIM™ TABLETS (white, round, scored) containing 80 mg trimethoprim and 400 mg sulfamethoxazole - bottles of 100 (NDC 13310-145-01) and 500 (NDC 13310-145-05). Imprint on tablets (debossed): (front) BACTRIM

Store at 20° to 25°C (68° to 77°F).
[See USP Controlled Room Temperature]

SOURCE: Package insert data:

Sulfa Allergy



National Institutes of Health, U.S. National Library of Medicine, DailyMed Database.
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Sulfonamides (anti-bacterial)