Ciprofloxacin (Cipro) Classification
Ciprofloxacin (Cipro) belongs to the fluoroquinolone class of antibiotics, specifically categorized as a second-generation fluoroquinolone. 1
Fluoroquinolone Classification System
Fluoroquinolones are categorized into generations based on their antimicrobial spectrum and structural modifications:
- First generation: Includes the prototype quinolone nalidixic acid (approved in 1964)
- Second generation: Includes ciprofloxacin, levofloxacin, norfloxacin, and ofloxacin
- Enhanced Gram-negative coverage including activity against Pseudomonas aeruginosa
- Ciprofloxacin became the first fluoroquinolone approved for pediatric use in 2004 1
- Third generation: Includes gemifloxacin
- Increased activity against Streptococcus pneumoniae while maintaining Gram-negative coverage
- Fourth generation: Includes moxifloxacin
- Maintains Gram-positive and Gram-negative activity with increased anaerobic coverage 1
Mechanism of Action
Fluoroquinolones, including ciprofloxacin, exert their bactericidal activity through:
- Inhibition of DNA gyrase (topoisomerase II) and topoisomerase IV 1, 2
- This inhibition impedes the formation of supercoiled DNA, inhibits relaxation of supercoiled DNA, and promotes double-strand DNA breakage 1
- The mechanism differs from other antibiotic classes (penicillins, cephalosporins, aminoglycosides, macrolides, and tetracyclines), explaining why organisms resistant to these classes may remain susceptible to fluoroquinolones 2
Antimicrobial Spectrum
Ciprofloxacin demonstrates:
- Excellent activity against Haemophilus influenzae and Moraxella catarrhalis 1
- Strong activity against most Gram-negative bacteria including Pseudomonas aeruginosa 2
- Limited activity against Streptococcus pneumoniae (AUC-to-MIC ratio of only 10-20, whereas the target ratio is 25-30) 1
- May require combination with adequate Gram-positive therapy (e.g., clindamycin) for certain infections 1
Important Considerations and Safety
When using ciprofloxacin, be aware of:
- Tendon rupture risk: Fluoroquinolones can cause tendinopathy and Achilles tendon rupture, particularly in patients over 60 years, those taking corticosteroids, or with renal dysfunction 2
- Drug interactions: Absorption is inhibited by multivalent cations (magnesium, aluminum, iron, calcium) 1
- Resistance concerns: Fluoroquinolone use can select for resistance in organisms like Pseudomonas aeruginosa, staphylococci, and pneumococci 1
- Pediatric use: Generally not recommended in children under 18 years except for specific serious infections due to concerns about effects on developing cartilage 1
Clinical Applications
Ciprofloxacin is FDA-approved for various infections including:
- Urinary tract infections
- Respiratory tract infections
- Skin and soft tissue infections
- Bone and joint infections
- Gastrointestinal infections (including traveler's diarrhea)
- Inhalational anthrax 2
For certain conditions like pouchitis, ciprofloxacin is considered first-line therapy due to better tolerability and potentially greater efficacy than alternatives like metronidazole 1.
Remember that fluoroquinolones should be used judiciously to minimize resistance development and should be reserved for infections where no safe and effective alternative exists, especially in pediatric patients 1.