Trimethoprim/sulfadiazine

Trimethoprim/sulfadiazine is a combination antibiotic used to treat a variety of bacterial infections. It is a combination of two drugs, Trimethoprim and Sulfadiazine, which work together to inhibit the growth of bacteria.

Mechanism of Action

Trimethoprim and sulfadiazine work synergistically to inhibit the growth of bacteria. Trimethoprim inhibits the action of dihydrofolate reductase, an enzyme necessary for the synthesis of tetrahydrofolate. Tetrahydrofolate is essential for the synthesis of purine, pyrimidine, and certain amino acids. Sulfadiazine, on the other hand, inhibits the synthesis of dihydropteroate, a precursor of tetrahydrofolate. By inhibiting these two steps in the synthesis of tetrahydrofolate, the combination of trimethoprim and sulfadiazine effectively halts the growth of bacteria.

Indications

Trimethoprim/sulfadiazine is used to treat a variety of bacterial infections, including urinary tract infections, respiratory tract infections, skin and soft tissue infections, and gastrointestinal infections. It is also used in the treatment of Pneumocystis jirovecii pneumonia in patients with HIV/AIDS.

Side Effects

Common side effects of trimethoprim/sulfadiazine include nausea, vomiting, diarrhea, and rash. Serious side effects can include anemia, leukopenia, thrombocytopenia, and Stevens-Johnson syndrome.

Contraindications

Trimethoprim/sulfadiazine is contraindicated in patients with a known allergy to sulfonamides or trimethoprim. It is also contraindicated in patients with severe renal impairment, liver disease, or blood disorders.

Drug Interactions

Trimethoprim/sulfadiazine can interact with a number of other medications, including anticoagulants, antidiabetic drugs, and methotrexate. It can also interact with potassium-sparing diuretics, leading to hyperkalemia.

See Also

• Trimethoprim
• Sulfadiazine
• Antibiotics
• Bacterial Infections