Sulfamethoxazole-Trimethoprim is a combination of two active ingredients used to treat a certain type of bacterial infection. Sulfamethoxazole is an antibiotic that is most commonly used in combination with trimethoprim that inhibits dihydropteroate synthase preventing the formation of dihydropteroate acid. It is a precursor of folic acid which is required for bacterial growth. It is a bacteriostatic antibacterial agent that interferes with the folic acid synthesis in susceptible bacteria.

Trimethoprim is an antibacterial and antiprotozoal property. It acts as a pyrimidine inhibitor of bacterial dihydrofolate reductase, it binds tightly to the bacterial enzyme, blocking the production of tetrahydrofolic acid from dihydrofolic acid.

Class of Drugs – Antibiotics

Molecular Formula – C₁₀H₁₁N₃O₃S + C₁₄H₁₈N₄O₃

Molecular Weight – 253.28 g/mol + 290.32 g/mol

Working: Given a combination of two ingredients is used to reduce the ability of some bacteria to utilize folic acid for growing. Sulfamethoxazole / Trimethoprim is an anti-bacterial sulfonamide that disrupts the production of dihydrofolic acid while trimethoprim disrupts the production of tetrahydrofolic acid. This medicine inhibits the production of tetrahydrofolic acid by inhibiting the enzyme responsible for making tetrahydrofolic acid from dihydrofolic acid. These two important steps required in the production of bacterial proteins are interrupted, and the combination is more effective than either drug alone.

Uses: This mentioned medication is a combination of two antibiotics, which is used to treat a wide variety of bacterial infections like a middle ear, urine, respiratory, and intestinal infections. Sulfamethoxazole / Trimethoprim also prevents and treats a certain type of pneumonia. This drug should not be used in children less than 2 months of age due to the risk of serious side effects.

Popular Brands and Dosages: This combination of two antibiotic medicine is used in a popular brand medicine as given below:

• Bactrim DS: 800 mg/ 160 mg
• Bactrim: 400 mg/ 80 mg

This medicine is not recommended in people with severe liver disease, kidney disease, and low platelets.