Trimethoprim

Antibiotic used to treat bacterial infections

Trimethoprim
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Trimethoprim is an antibiotic used primarily in the treatment of urinary tract infections, although it is also used for other types of bacterial infections. It is often used in combination with sulfamethoxazole as co-trimoxazole.

Mechanism of action

Trimethoprim works by inhibiting the bacterial enzyme dihydrofolate reductase, which is involved in the synthesis of tetrahydrofolate, a form of folic acid that bacteria need to produce DNA, RNA, and proteins. By blocking this enzyme, trimethoprim effectively halts bacterial growth.

Diagram of the tetrahydrofolate synthesis pathway.

Uses

Trimethoprim is primarily used to treat urinary tract infections, but it is also effective against other types of infections such as respiratory tract infections and traveler's diarrhea. It is often used in combination with sulfamethoxazole to enhance its antibacterial effect.

Side effects

Common side effects of trimethoprim include nausea, vomiting, and rash. More serious side effects can include bone marrow suppression, which can lead to anemia, leukopenia, and thrombocytopenia.

Resistance

Bacterial resistance to trimethoprim can occur through various mechanisms, including the production of an altered dihydrofolate reductase enzyme that is not inhibited by the drug. Resistance is a growing concern, particularly in the treatment of urinary tract infections.

History

Trimethoprim was first synthesized in the 1960s and was introduced into clinical use in the 1970s. It has since become a widely used antibiotic, particularly in combination with sulfamethoxazole.

Related pages

• Antibiotic
• Urinary tract infection
• Sulfamethoxazole
• Co-trimoxazole