• Type: Fluroquinolones
  • Dosage Forms: 200,300,400, topical/otic
  • Common Trade Names: Floxin, Floxin Otic

Adult Dosing

Infections, bacterial

  • 200-400mg PO q12h

Infections, chlamydial

  • 300mg PO q12h x 7d

Urethritis, nongonococcal

  • 300mg PO q12h x 7d


  • 300mg PO q12h x 10d

Typhoid fever

  • 400mg PO q12h x 7-14d

Otitis Externa

  • 5 drops in affected ear BID x 7 days[1]
    • Safe with perforations

Pediatric Dosing


  • >12yrs: 400mg PO BID x 14d

Typhoid fever

  • 20mg/kg BID x 10d, max 400mg/dose

Otitis Externa

  • 6mo-13 yo: 5 drops in affected ear BQD x 7 days
  • >13 yo: 5 drops in affected ear BID x 7 days[1]

Special Populations

  • Pregnancy: C (risk cannot be excluded)
  • Lactation: probably safe
  • Renal Dosing
    • Adult
      • GFR 20-50: give q24h
      • GFR < 20: give usual dose x1, then decrease dose 50% q24h
      • HD: give 100-200mg after dialysis
    • Pediatric
      • specific adjustment not defined though adjustment may be required
  • Hepatic Dosing
    • Adult
      • cirrhosis: max 400mg/24h
    • Pediatric
      • specific adjustment not defined though adjustment may be required


  • Allergy to class/drug
  • myasthenia gravis
  • prolonged QT
  • history of torsades de pointes
  • caution if ventricular arrhythmias, bradycardia, recent MI
  • caution if CHF, patient > 60
  • caution if history of renal, heart, lung transplant
  • caution in seizure disorder
  • caution in DM

Adverse Reactions


  • Anaphylaxis
  • Seizure
  • Phototoxicity
  • Superinfection
  • Increased ICP
  • Toxic psychosis
  • Vasculitis
  • Serum sickness
  • Hypersensitivity pneumonitis
  • QT prolongation
  • Torsades de pointes
  • Peripheral neuropathy
  • Hepatotoxicity
  • Nephrotoxicity
  • Crystalluria
  • Myelosuppression
  • Blood dyscrasias
  • Tendonitis or tendon rupture (black box warning) - increased risk in age >60, immunosuppressed, corticosteroid use
  • Myasthenia exacerbation
  • Severe Hypoglycemia [2]
  • mental health effects



  • Half-life: 4-8h, if GFR < 10 then 17-28h
  • Metabolism: liver minimally
  • Excretion: urine primarily (70-90% unchanged), bile/feces (4-8%)
  • Mechanism of Action: inhibits DNA gyrase and topoisomerase IV

Antibiotic Sensitivities[3]

Group Organism Sensitivity
Gram PositiveStrep. Group A, B, C, GI
Strep. PneumoniaeI
Viridans strepR
Strep. anginosus gpR
Enterococcus faecalisU
Enterococcus faeciumR
Staph. EpidermidisS
C. jeikeiumR
L. monocytogenesR
Gram NegativesN. gonorrhoeaeI
N. meningitidisS
Moraxella catarrhalisS
H. influenzaeS
E. coliS
Klebsiella spS
E. coli/Klebsiella ESBL+S
E coli/Klebsiella KPC+R
Enterobacter sp, AmpC negS
Enterobacter sp, AmpC posS
Serratia spS
Serratia marcescensX1
Salmonella spS
Shigella spS
Proteus mirabilisS
Proteus vulgarisS
Providencia sp.S
Morganella sp.S
Citrobacter freundiiS
Citrobacter diversusS
Citrobacter sp.S
Aeromonas spS
Acinetobacter sp.I
Pseudomonas aeruginosaI
Burkholderia cepaciaR
Stenotrophomonas maltophiliaR
Yersinia enterocoliticaS
Francisella tularensisX1
Brucella sp.X1
Legionella sp.S
Pasteurella multocidaS
Haemophilus ducreyiX1
Vibrio vulnificusX1
MiscChlamydophila spS
Mycoplasm pneumoniaeS
Rickettsia spX1
Mycobacterium aviumX1
Bacteroides fragilisR
Prevotella melaninogenicaI
Clostridium difficileX1
Clostridium (not difficile)I
Fusobacterium necrophorumX1
Peptostreptococcus sp.I


  • S susceptible/sensitive (usually)
  • I intermediate (variably susceptible/resistant)
  • R resistant (or not effective clinically)
  • S+ synergistic with cell wall antibiotics
  • U sensitive for UTI only (non systemic infection)
  • X1 no data
  • X2 active in vitro, but not used clinically
  • X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
  • X4 active in vitro, but not clinically effective for strep pneumonia

See Also


  1. Clinical Practice Guideline: Acute Otitis Externa Executive Summary. Otolaryngology -- Head and Neck Surgery 2014 150: 161 DOI: 10.1177/0194599813517659 PDF
  2. FDA updates warnings for fluoroquinolone antibiotics on risks of mental health and low blood sugar adverse reactions. US Food and Drug Administration. https://www.fda.gov/newsevents/newsroom/pressannouncements/ucm612995.htm. Updated July 10, 2018. Accessed Oct 22, 2018.
  3. Sanford Guide to Antimicrobial Therapy 2014
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