From Wikipedia, the free encyclopedia
Trimethoprim (INN) (pronounced /traɪˈmɛθəprɪm/) is a bacteriostatic antibiotic mainly used in the prophylaxis and treatment of urinary tract infections. It belongs to the class of chemotherapeutic agents known as dihydrofolate reductase inhibitors. Trimethoprim was formerly marketed by GlaxoWellcome under trade names including Proloprim, Monotrim and Triprim; but these trade names have been licensed to various generic pharmaceutical manufacturers. In clinical use it is often abbreviated TRI or TMP; its common laboratory abbreviation is W.
[edit] Mechanism of action
Trimethoprim acts by interfering with the action of bacterial dihydrofolate reductase, inhibiting synthesis of tetrahydrofolic acid. Tetrahydrofolic acid is an essential precursor in the de novo synthesis of the DNA nucleotide thymidine. Bacteria are unable to take up folic acid from the environment (i.e. the infection host) and are thus dependent on their own de novo synthesis. Inhibition of the enzyme starves the bacteria of nucleotides necessary for DNA replication.
[edit] Co-trimoxazole
Trimethoprim was commonly used in combination with sulfamethoxazole, a sulfonamide antibiotic, which inhibits an earlier step in the folate synthesis pathway (see diagram above). This combination, also known as co-trimoxazole, TMP-sulfa, or TMP-SMX, results in an in vitro synergistic antibacterial effect by inhibiting successive steps in folate synthesis. This claimed benefit was not seen in general clinical use.[1] [2] Its use has been declining due to reports of sulfamethoxazole bone marrow toxicity, resistance and lack greater efficacy in treating common urine and chest infections,[3][4][5][6] and side effects of antibacterial sulfonamides. As a consequence, the use of co-trimoxazole was restricted in 1995.[7]
[edit] Clinical indications
Trimethoprim, used as monotherapy, is indicated for the prophylaxis and treatment of urinary tract infections (urethritis). Co-trimoxazole, with its greater efficacy against a limited number of bacteria, remains indicated for some infections; for example, it is used as prophylaxis in patients at risk for Pneumocystis jirovecii pneumonia (e.g. AIDS patients and those with some hematological malignancies) and as therapy in Whipple's disease.
[edit] Footnotes
- ^ Brumfitt W, Hamilton-Miller JM (Dec 1993). "Reassessment of the rationale for the combinations of sulphonamides with diaminopyrimidines". J Chemother 5 (6): 465-9. PMID 8195839.
- ^ Brumfitt W, Hamilton-Miller JM (Feb 1994). "Limitations of and indications for the use of co-trimoxazole". J Chemother 6 (1): 3-11. PMID 8071675.
- ^ Bean DC, Livermore DM, Papa I, Hall LM (Nov 2005). "Resistance among Escherichia coli to sulphonamides and other antimicrobials now little used in man". J Antimicrob Chemother 56 (5): 962-4. doi:10.1093/jac/dki332. PMID 16150859.
- ^ Felmingham D, Reinert RR, Hirakata Y, Rodloff A (Sep 2002). "Increasing prevalence of antimicrobial resistance among isolates of Streptococcus pneumoniae from the PROTEKT surveillance study, and compatative in vitro activity of the ketolide, telithromycin". J Antimicrob Chemother 50 (Suppl S1): 25-37. PMID 12239226.
- ^ Johnson JR, Manges AR, O'Bryan TT, Riley LW (Jun 29 2002). "A disseminated multidrug-resistant clonal group of uropathogenic Escherichia coli in pyelonephritis". Lancet 359 (9325): 2249-51. PMID 12103291.
- ^ Lawrenson RA, Logie JW (Dec 2001). "Antibiotic failure in the treatment of urinary tract infections in young women". J Antimicrob Chemother 48 (6): 895-901. doi:10.1093/jac/48.6.895. PMID 11733475. - suggest some small advantage in UTIs
- ^ "Co-trimoxazole use restricted" (Dec 1995). Drug Ther Bull 33 (12): 92-3. PMID 8777892.
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Antibacterials for systemic use: sulfonamides (sulfa drugs) and trimethoprim (J01E) |
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| Trimethoprim and derivatives |
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| Short-acting sulfonamides |
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| Intermediate-acting sulfonamides |
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| Long-acting sulfonamides |
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| Combinations |
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