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Clinician’s Corner: Fluoroquinolones

Mechanism:  involves inhibition of enzymes the bacteria need for protein synthesis.

Fluoroquinolones are considered bactericidal, kicking the bacteria outright.

Indications for use:

Excellent Gram positive & gram-negative coverage. Activity against Pseudomonas.

Coverage of Anaerobes is poor.


  • May cause heart rhythm disturbances
  • Increase risk of sunburn. Use a sunscreen.
  • Mental health: may cause mood or behavior changes such as nervousness, confusion, agitation, paranoia, hallucinations. (FDA Black Box warning)
  • Tendonitis: may not give to patients under 18! (FDA Black Box warning). May weaken tendons.
  • Avoid in pregnant women, nursing women & children due cartilage erosion in growing bone tissue. (FDA Black Box warning) Pregnancy Category D
  • May cause significant antibiotic associated diarrhea
  • May affect blood sugar levels, especially in diabetics (esp. renal impaired). High blood sugar can occur within the first 3 days. Low blood sugar usually doesn’t show up until after 3 days.  Advise extra blood sugar monitoring. (FDA Black Box warning)
  • 2018: increased risk of the aorta (the main artery of body) rupturing, causing massive bleeding and potentially, death.

Side effects:  Watch for rash, hives and possible sunburn.

Drug Interactions:

Do not take with antacids, multivitamins, iron, calcium, magnesium, for at least 2 hours.

Increases theophylline levels

May increase prothrombin time or INR (warfarin interaction)

Patient Education:

  • Use sunscreen if outside.
  • May take with food to decrease GI upset.
  • Avoid iron, magnesium, calcium, zinc
  • Finish the entire course of therapy

Most common Drugs & dosage of this class-Quinolones

Ciprofloxacin (Cipro®) FDA initial approval 1987

  • Primary use today is for urinary tract infections UTI’s), skin/soft tissue and GI infections. Not for respiratory infections. Not for gonorrhea infections.
  • Historical note: In August 2000, the FDA approved ciprofloxacin for management of postexposure inhalational anthrax. First antimicrobial drug approved by the FDA for use in treating an infection due to a biological weapon. 

Levofloxacin (Levaquin®)  (FDA approved: 12/1998)

  • Can be used for both UTI and respiratory infections

Moxifloxin (Avelox®)  (FDA approved 1999)

  • Little kidney penetration, used only for respiratory infection, and skin and soft tissue infections. Minimal value for urinary tract infections.

Delafloxacin (Baxdela®) FDA approved 2018

For treatment of Acute Bacterial Skin and Skin Structure Infections (ABSSSI’s)

More active than other FQ’s against Gram positive organisms such as multi drug resistant

Strep pneumo and MRSA (methicillin resistant S. aureus).

Like other FQ: May cause tendinopathy.  Avoid polyvalent cations with administration.

  • Does not prolong QTc interval
  • Does not cause photosensitivity

Gemifloxacin (Factive) –FDA approved 2003

Was used for exacerbations of chronic bronchitis but is seldom used due to causing red exfoliative rash.


Resistance: we see major resistance to fluoroquinolones. Here are some resistance stats from our area: Escherichia coli accounts for 75-95% of urinary tract infections.

Streptococcus pneumoniae was a big player in the pre-antibiotic era, thanks to child immunizations it is seen less frequently. However, is the most common agent in hospitalizations.

  USA 2017 UPMC Altoona

Altoona, Pa

Mount Nittany, State College PA
E. coli resistance 25% 27% 16%
Strep pneumo resistance 1% 5% 0%

Where our Thompson Pharmacies are located, we have a community with an older population.  State College PA is a more affluent, healthier, younger, and better educated community, less likely to demand or need antibiotic therapy.  There is a distance of about 35 miles between the two municipalities, but a major gap in fluoroquinolone resistance.

Your Thompson Pharmacist is a go-to resource for antibiotic therapy.  Always take your antibiotic as prescribed and be sure to finish the entire dose.  Got a Question? Go Ahead and Ask… at Thompson Pharmacy it’s All for YOU!