Tablet Ciprofloxacin (Cipro)

Drug Class

Fluoroquinolone antibiotic — bactericidal; inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, blocking DNA replication and repair.

Available Formulations

Form	Strengths
Immediate-release tablet	250 mg, 500 mg, 750 mg
Extended-release tablet (Cipro XR)	500 mg, 1000 mg

Indications & Dosing

Infection	Dose	Frequency	Duration
Uncomplicated UTI	250 mg	Every 12 h	3 days
Complicated UTI / Pyelonephritis	500 mg	Every 12 h	7–14 days
Respiratory tract infections	500–750 mg	Every 12 h	7–14 days
Skin & soft tissue infections	500–750 mg	Every 12 h	7–14 days
Bone & joint infections	500–750 mg	Every 12 h	4–8 weeks
Infectious diarrhea / Traveler's diarrhea	500 mg	Every 12 h	1–5 days
Typhoid fever	500 mg	Every 12 h	10 days
Gonorrhea (uncomplicated)	500 mg	Single dose	—
Inhalation anthrax (post-exposure)	500 mg	Every 12 h	60 days
Aeromonas infections	500 mg	Every 12 h	Per response
IV equivalent	400 mg	Every 12 h	—

Spectrum of Activity

Gram-negative: E. coli, Klebsiella, Enterobacter, Salmonella, Shigella, Pseudomonas aeruginosa, Aeromonas, H. influenzae, Neisseria
Gram-positive (limited): S. aureus (MSSA), S. epidermidis
Atypicals: Mycoplasma, Chlamydia, Legionella
Poor coverage: Streptococci, anaerobes, MRSA

Pharmacokinetics

Parameter	Value
Bioavailability (oral)	~70–80%
Half-life	~4–6 hours
Protein binding	~20–40%
Route of elimination	Renal (primary) + hepatic
Dose adjustment needed	Yes, if CrCl < 30 mL/min

Side Effects

Common

Nausea, vomiting, diarrhea
Headache, dizziness

Serious / Notable

Effect	Details
Tendonitis / Tendon rupture	Especially Achilles; risk higher in elderly, corticosteroid users
QT prolongation	Avoid with other QT-prolonging drugs
Peripheral neuropathy	May be irreversible
CNS effects	Seizures, confusion, tremors
C. difficile colitis	Risk with any antibiotic
Photosensitivity	Avoid prolonged sun exposure
Hypoglycemia/hyperglycemia	Especially in diabetics on hypoglycemics

⚠️ Black Box Warning (FDA): Tendinitis and tendon rupture; peripheral neuropathy; CNS effects; exacerbation of myasthenia gravis.

Contraindications

Hypersensitivity to ciprofloxacin or any fluoroquinolone
Concomitant use with tizanidine (severe hypotension risk)
Myasthenia gravis (may worsen neuromuscular blockade)
Children < 18 years (except anthrax, complicated UTI — specific indications only; risk of arthropathy)

Key Drug Interactions

Drug/Group	Interaction
Antacids (Al/Mg), Sucralfate, Iron, Zinc	Reduce ciprofloxacin absorption — take 2 h before or 6 h after
Theophylline	Elevated theophylline levels → toxicity
Warfarin	Increased anticoagulant effect (monitor INR)
NSAIDs	Increased CNS stimulation/seizure risk
QT-prolonging drugs	Additive QT prolongation
Tizanidine	Contraindicated — severe hypotension
Metformin	May increase metformin exposure

Special Populations

Renal impairment: Reduce dose if CrCl < 30 mL/min
Pregnancy: Category C — avoid unless benefit outweighs risk; fluoroquinolones generally avoided
Lactation: Excreted in breast milk — use with caution
Elderly: Higher risk of tendon rupture, CNS effects, QT prolongation

Patient Counseling Points

Take with a full glass of water; stay well-hydrated.
Can be taken with or without food (avoid dairy/calcium-rich foods close to dosing).
Avoid antacids, iron, or calcium supplements within 2–6 hours of dosing.
Stop and report immediately if tendon pain/swelling occurs.
Avoid excessive sun exposure.
Complete the full course even if feeling better.

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