Generic Name

Trimethoprim

Brand Names
Sulfamethoxazole, Sulfamethox-TMP, Bactrim, Sulfatrim, Sulfameth
FDA approval date: July 01, 1983
Classification: Dihydrofolate Reductase Inhibitor Antibacterial
Form: Injection, Tablet, Suspension, Solution

What is Sulfamethoxazole (Trimethoprim)?

To reduce the development of drug-resistant bacteria and maintain the effectiveness of sulfamethoxazole and trimethoprim tablets and other antibacterial drugs, 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 sulfamethoxazole and trimethoprim in pediatric patients under two years of age. Sulfamethoxazole and trimethoprim 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 influenzaewhen a physician deems that sulfamethoxazole and trimethoprim 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.

Brand Information

    Sulfamethoxazole and Trimethoprim (Sulfamethoxazole and Trimethoprim)
    1Rx only
    To reduce the development of drug-resistant bacteria and maintain the effectiveness of sulfamethoxazole and trimethoprim tablets and other antibacterial drugs, sulfamethoxazole and trimethoprim tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.
    2DESCRIPTION
    Sulfamethoxazole and trimethoprim is a synthetic antibacterial combination product available in DS (double strength) tablets, each containing 800 mg sulfamethoxazole and 160 mg trimethoprim; in tablets, each containing 400 mg sulfamethoxazole and 80 mg trimethoprim for oral administration.
    Sulfamethoxazole Chemical Structure
    Trimethoprim is 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine; the molecular formula is C
    Trimethoprim Chemical Structure
    Inactive Ingredients: Docusate sodium, magnesium stearate, pregelatinized starch (maize), sodium benzoate, and sodium starch glycolate.
    3CLINICAL PHARMACOLOGY
    Sulfamethoxazole and trimethoprim is rapidly absorbed following oral administration. Both sulfamethoxazole and trimethoprim exist in the blood as unbound, protein-bound and metabolized forms; sulfamethoxazole also exists as the conjugated form. Sulfamethoxazole is metabolized in humans to at least 5 metabolites: the N
    3.1Geriatric Pharmacokinetics
    The pharmacokinetics of sulfamethoxazole 800 mg and trimethoprim 160 mg were studied in 6 geriatric subjects (mean age: 78.6 years) and 6 young healthy subjects (mean age: 29.3 years) using a non-U.S. approved formulation. Pharmacokinetic values for sulfamethoxazole in geriatric subjects were similar to those observed in young adult subjects. The mean renal clearance of trimethoprim was significantly lower in geriatric subjects compared with young adult subjects (19 mL/h/kg vs. 55 mL/h/kg). However, after normalizing by body weight, the apparent total body clearance of trimethoprim was on average 19% lower in geriatric subjects compared with young adult subjects.
    3.2Microbiology
    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.
    3.2.1Aerobic gram-positive microorganisms
    Streptococcus pneumoniae
    3.2.2Aerobic 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 flexneriShigella sonnei
    3.2.3Other Organisms
    Pneumocystis
    3.2.4Susceptibility Testing Methods
    When available, the clinical microbiology laboratory should provide the results of
    3.2.4.1Dilution Techniques
    Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized test method (broth or agar)
    3.2.4.2Diffusion Techniques
    Quantitative methods that require measurement of zone diameters can also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. The zone size provides an estimate of the susceptibility of bacteria to antimicrobial compounds. The zone size should be determined using a standardized test method
    A report of
    Quality Control
    Standardized susceptibility test procedures require the use of laboratory controls to monitor and ensure the accuracy and precision of supplies and reagents used in the assay and the techniques of the individuals performing the test
    4INDICATIONS AND USAGE
    To reduce the development of drug-resistant bacteria and maintain the effectiveness of sulfamethoxazole and trimethoprim tablets, USP and other antibacterial drugs, sulfamethoxazole and trimethoprim tablets, USP 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.
    4.1Urinary Tract Infections
    For the treatment of urinary tract infections due to susceptible strains of the following organisms:
    4.2Acute Otitis Media
    For the treatment of acute otitis media in pediatric patients due to susceptible strains of
    4.3Acute Exacerbations of Chronic Bronchitis in Adults
    For the treatment of acute exacerbations of chronic bronchitis due to susceptible strains of
    4.4Shigellosis
    For the treatment of enteritis caused by susceptible strains of
    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.
    4.5Traveler's Diarrhea in Adults
    For the treatment of traveler's diarrhea due to susceptible strains of enterotoxigenic
    5CONTRAINDICATIONS
    Sulfamethoxazole and trimethoprim tablets are contraindicated in patients with a known hypersensitivity to trimethoprim or sulfonamides, in patients with a history of drug-induced immune thrombocytopenia with use of trimethoprim and/or sulfonamides, and in patients with documented megaloblastic anemia due to folate deficiency.
    6WARNINGS
    Embryofetal Toxicity
    Some epidemiologic studies suggest that exposure to sulfamethoxazole and trimethoprim during pregnancy may be associated with an increased risk of congenital malformations, particularly neural tube defects, cardiovascular malformations, urinary tract defects, oral clefts, and club foot. If sulfamethoxazole and trimethoprim is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be advised of the potential hazards to the fetus.

    Hypersensitivity and Other Fatal Reactions

    Fatalities associated with the administration of sulfonamides, although rare, have occurred due to severe reactions, including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia and other blood dyscrasias.

    Sulfonamides, including sulfonamide-containing products such as sulfamethoxazole and trimethoprim, should be discontinued at the first appearance of skin rash or any sign of adverse reaction. In rare instances, a skin rash may be followed by a more severe reaction, such as Stevens-Johnson syndrome, toxic epidermal necrolysis, hepatic necrosis, and serious blood disorders (see PRECAUTIONS). Clinical signs, such as rash, sore throat, fever, arthralgia, pallor, purpura or jaundice may be early indications of serious reactions.

    Cough, shortness of breath, and pulmonary infiltrates are hypersensitivity reactions of the respiratory tract that have been reported in association with sulfonamide treatment.

    Thrombocytopenia

    Sulfamethoxazole and trimethoprim-induced thrombocytopenia may be an immune-mediated disorder. Severe cases of thrombocytopenia that are fatal or life threatening have been reported. Thrombocytopenia usually resolves within a week upon discontinuation of sulfamethoxazole and trimethoprim.

    Streptococcal Infections and Rheumatic Fever

    The sulfonamides should not be used for treatment of group A β-hemolytic streptococcal infections. In an established infection, they will not eradicate the streptococcus and, therefore, will not prevent sequelae such as rheumatic fever.

    Clostridium Difficile
    Associated Diarrhea
    Clostridium difficile
    associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including sulfamethoxazole and trimethoprim, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.

    C. difficile
    produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.

    If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

    Adjunctive Treatment with Leucovorin for Pneumocystis jiroveci Pneumonia

    Treatment failure and excess mortality were observed when trimethoprim-sulfamethoxazole was used concomitantly with leucovorin for the treatment of HIV positive patients with Pneumocystis jiroveci pneumonia in a randomized placebo controlled trial.6 Co-administration of trimethoprim-sulfamethoxazole and leucovorin during treatment of Pneumocystis jiroveci pneumonia should be avoided.
    7ADVERSE REACTIONS
    The most common adverse effects are gastrointestinal disturbances (nausea, vomiting, anorexia) and allergic skin reactions (such as rash and urticaria).
    • Thrombotic thrombocytopenia purpura
    • Idiopathic thrombocytopenic purpura
    • QT prolongation resulting in ventricular tachycardia and
    8DOSAGE AND ADMINISTRATION

    Sulfamethoxazole and trimethoprim tablets are contraindicated in pediatric patients less than 2 months of age.
    8.1For Patients with Impaired Renal Function
    When renal function is impaired, a reduced dosage should be employed using the following table:
    8.2Acute Exacerbations of Chronic Bronchitis in Adults
    The usual adult dosage in the treatment of acute exacerbations of chronic bronchitis is 1 sulfamethoxazole and trimethoprim DS (double strength) tablet or 2 sulfamethoxazole and trimethoprim tablets every 12 hours for 14 days.
    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.
    8.3Traveler's Diarrhea in Adults
    For the treatment of traveler’s diarrhea, the usual adult dosage is 1 sulfamethoxazole and trimethoprim DS (double strength) tablet or 2 sulfamethoxazole and trimethoprim tablets every 12 hours for 5 days.
    9HOW SUPPLIED
    Sulfamethoxazole and Trimethoprim Tablets USP, 400 mg/80 mg are white to off-white circular, beveled edge uncoated tablets, debossed with “H 48” on one side and deep break line on the other side.



    Sulfamethoxazole and Trimethoprim Tablets USP, 800 mg/160 mg are white to off-white oval, beveled edge uncoated tablets, debossed with “H 49” on one side and deep break line on other side.

    55700-611-10
    55700-611-14
    55700-611-20
    55700-611-28
    10REFERENCES
    1. Kremers P, Duvivier J, Heusghem C. Pharmacokinetic Studies of Co-Trimoxazole in Man after Single and Repeated Doses.
    2. Kaplan SA, et al. Pharmacokinetic Profile of Trimethoprim-Sulfamethoxazole in Man.
    3. Varoquaux O, et al. Pharmacokinetics of the trimethoprim-sulfamethoxazole combination in the elderly.
    4. Rudoy RC, Nelson JD, Haltalin KC.
    5. Clinical and Laboratory Standards Institute.
    6. Safrin S, Lee BL, Sande MA. Adjunctive folinic acid with trimethoprim-sulfamethoxazole for
    7. Hardy DW, et al. A controlled trial of trimethoprim-sulfamethoxazole or aerosolized pentamidine for secondary prophylaxis of
    8. Marinella Mark A. 1999. Trimethoprim-induced hyperkalemia: An analysis of reported cases.
    9. Margassery, S. and B. Bastani. 2002. Life threatening hyperkalemia and acidosis secondary to trimethoprim-sulfamethoxazole treatment.
    10. Brumfitt W, Pursell R. Trimethoprim/Sulfamethoxazole in the Treatment of Bacteriuria in Women.
    11. Masur H. Prevention and treatment of
    12. Recommendations for prophylaxis against
    13. CDC Guidelines for prophylaxis against
    14. Clinical and Laboratory Standards Institute.
    15. Clinical and Laboratory Standards Institute (CLSI).
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    Made in India
    Code: TS/DRUGS/22/2009

    Revised: 12/2017
    Sulfamethoxazole has been selected.