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Fleroxacin; Indications/Uses, Dosage, Side Effects, Interactions

February 7, 2026 5 min read
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Medically reviewed by RX Editorial Board Medical Review Team
Last updated February 7, 2026
Medical review Clinically checked
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Fleroxacin is a broad-spectrum antimicrobial fluoroquinolone. It strongly inhibits the DNA-supercoiling activity of DNA gyrase. Fleroxacin is a fluoroquinolone antibiotic that is 4-oxo-1,4-dihydroquinoline which is substituted at positions 1, 3, 6, 7 and 8 by 2-fluoroethyl, carboxy, fluoro, 4-methyl piperazine-1-yl and fluoro groups, respectively. It is active against many Gram-positive and Gram-negative bacteria. It has a role as a topoisomerase IV inhibitor, an antibacterial drug, and an EC 5.99.1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor. It is a member of quinolines, a fluoroquinolone antibiotic, a difluorobenzene, an N-alkylpiperazine, and a monocarboxylic acid.

Mechanism of action of Fleroxacin

The inhibition of DNA gyrase and DNA topoisomerase 2 leads ultimately to cell death as these enzymes are required for bacterial DNA replication, transcription, repair, strand supercoiling repair, and recombination.

or

Fleroxacin is a bactericidal drug that inhibits bacterial DNA gyrase and topoisomerase IV. Like other quinolones and fluoroquinolones, the compound eradicates bacteria by interfering with DNA replication (bacterial DNA replication, transcription, repair and recombination).[2][3][4] Fleroxacin is active against many Gram-positive and Gram-negative bacteria. It is especially active against Shigella species., Salmonella sp., Escherichia coli, Branhamella catarrhalis, Haemophilus influenzae, Neisseria gonorrhoeae, Yersinia enterocolitica, Serratia marcescens, Staphylococcus aureus, Pseudomonas aeruginosa.[5][6]

Indications of Fleroxacin

  • Fleroxacin is a broad-spectrum antimicrobial fluoroquinolone.
  • Fleroxacin is effective in the treatment of a wide variety of infections, particularly uncomplicated cystitis in women,
  • Acute uncomplicated pyelonephritis,
  • Gonorrhea,
  • Bacterial enteritis,
  • Traveler’s diarrhea, 
  • Respiratory tract infections ( including exacerbation of chronic bronchitis).[9][10]

Contraindications of Fleroxacin

Please consult your physician or pharmacist or product package for this information.

Dosage of Fleroxacin

Fleroxacin (Ro 23-6240; AM-833) is a new trifluorinated quinolone exhibiting high activity against a broad spectrum of gram-negative and gram-positive bacteria. Healthy male volunteers received, according to a randomized scheme, oral doses of 200, 400, or 800 mg of fleroxacin in tablet form, an intravenous infusion of 100 mg, or 400 mg of fleroxacin orally together with 1,000 mg of probenecid. Fleroxacin is characterized pharmacokinetically by a long elimination half-life (9 to 10 h) and high concentrations in plasma (e.g., the maximum concentration of 2.3 micrograms/ml after an oral dose of 200 mg). The volume of distribution clearly exceeds 1 liter/kg and suggests good tissue penetration. Within 60 h, the cumulative urinary recovery of unchanged drug amounted to 50 to 60% of the dose. The renal clearance of unbound drug was 137 ml/min, and probenecid had no significant effect on renal elimination. A good linear correlation (r = 0.999) was found between doses from 100 to 800 mg and the resulting values of area under the concentration-time curve. The absolute bioavailability of the administered tablet was practically 100%. During oral multiple dosing of 800 or 1,200 mg of fleroxacin once a day over 10 consecutive days, the accumulation of the drug in plasma was close to the theoretically predicted value of 1.3 and reflected the persistence of linear pharmacokinetics.[#]

Side Effects of Fleroxacin

The most common

  • allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
  • leukopenia/leukemia
  • hemolytic anemia
  • serum sickness
  • agranulocytosis
  • pain, swelling, irritation where injected
  • stomach upset
  • sweating
  • skin color change, mild diarrhea
  • mild nausea
  • loss of appetite
  • vaginal discharge and itching
  • swelling of feet or legs
  • chest pain
  • constipation
  • a cough
  • diarrhea or loose stools
  • difficulty with breathing
  • dizziness
  • heartburn

More common

Drug Interactions of Fleroxacin

Fleroxacin may interact with following drugs, supplements, & may change the efficacy of drugs

Pregnancy and Lactation of Fleroxacin

FDA pregnancy  risk category N (not known)

References

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Fleroxacin; Indications/Uses, Dosage, Side Effects, Interactions
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