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Drug Guide


  • Mechanism of Action

  • Inhibits the production of dihydrofolate reductase (DHFR), resulting in reduced conversion of dihydrofolic acid to active tetrahydrofolic acid - interfering with bacterial synthesis of nucleic acids.
  • Pharmacology
  • Higher affinity for bacterial dihydrofolate reductase than for human DHFR.
  • Mostly excreted unmetabolised into urine in high concentrations, resulting in its effect directly within the bladder.
  • Microbiology

  • Active against most GI normal flora, the most common cause of UTI.

Clinical Use

  • Indications

  • Uncomplicated symptomatic urinary tract infection.
  • Contraindications

  • Megaloblastic anaemia due to folate deficiency.
  • Adverse Effects
  • Rash / pruritis
  • Nausea / vomiting
  • Elevated LFTs
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