Generic Name

Cipro

Mechanism

• Dual inhibition of bacterial enzymes:
• DNA gyrase (topoisomerase II) – interferes with negative supercoiling of bacterial DNA.
• Topoisomerase IV – disrupts chromosomal segregation during cell division.
• Results in trapped cleavage complexes that prevent DNA replication and transcription, leading to bacterial cell death.
• High affinity for gram‑negative and many gram‑positive organisms; less active against anaerobes and *Staphylococcus aureus* (unless MRSA‑susceptible).

Pharmacokinetics

• Absorption: Oral bioavailability ~70 % (≈ 50 % when taken with calcium‑rich foods).
• Distribution: Widely dispersed into tissues; excellent penetration into the urinary tract, lungs, bone, and abscesses.
• Protein binding: ~30–40 % (moderately bound).
• Metabolism: Minimal hepatic metabolism – primarily unchanged.
• Elimination: Renally excreted (59 % unchanged; 15 % via the liver); dose adjustment required for reduced CrCl.
• Half‑life: 4 – 8 h (≈ 6 h in healthy adults).

Indications

• Urinary Tract Infections (UTIs): uncomplicated cystitis, complicated pyelonephritis.
• Respiratory Tract Infections: acute bacterial bronchitis, community‑acquired pneumonia (often as second‑line).
• Skin and Soft Tissue Infections: erysipelas, cellulitis, infected wounds, anthrax, staphylococcal infections (if susceptible).
• Gastrointestinal: bacterial dysentery, *Campylobacter*, amoebic colitis (when appropriate).
• Bone & Joint: osteomyelitis, spondylitis (often combination therapy).
• Endophthalmitis and Abdominal sepsis (in select cases).
• Traveler’s diarrhea (bacterial etiologies).
• Anthrax prophylaxis and treatment.

Contraindications

• Hypersensitivity to ciprofloxacin or any fluoroquinolone.
• Pregnancy: Category C (risk vs. benefit).
• Lactation: excreted in milk; caution advised.
• Children <18 yrs: risk of musculoskeletal toxicity (tendon rupture, growth plate changes).
• Myasthenia gravis: can worsen neuromuscular transmission.
• QT‑interval prolongation: avoid in patients with ventricular arrhythmias or electrolyte disturbances.
• Tendinopathies: history increases risk of rupture (see below).
• Severe hepatic dysfunction: reduced clearance.

Warnings:
• Tendon rupture (common: Achilles, Flexor Hallucis Longus).
• CNS effects (seizures, ataxia, hallucinations).
• Phototoxicity (sunlight/UV exposure).
• Metabolic disturbances: ↓glycemic control, hypoglycemia in diabetics, and electrolyte shifts (especially Mg, K).

Dosing

• Sublingual preparation optional for severe vomiting.
• Extended‑release not available; use standard tablets.
• Take half hour before meals if renal dosing is required (to avoid GI irritation).

Adverse Effects

Common (≥ 5 % incidence)
• Nausea, vomiting
• Diarrhea (including *Clostridioides difficile* colitis)
• Headache, dizziness
• Insomnia

Serious (≤ 1 % incidence)
• Tendinopathy / tendon rupture
• Phototoxic reactions (erythema, burns)
• CNS toxicity: seizures, altered sensorium, hallucinations
• QT prolongation → arrhythmia
• Hypersensitivity reactions: rash, urticaria, anaphylaxis
• Hypoglycemic crisis in diabetic patients
• *C. difficile*‑associated pseudomembranous colitis

Monitoring

• Renal function: CrCl at baseline, every 2–3 days if CrCl ↓ 50 %, then weekly until stable.
• Hepatic enzymes: baseline LFTs; repeat if clinically indicated.
• Serum electrolytes: Mg, K, Ca (especially in ECMO, burns).
• ECG: baseline if history of arrhythmia; repeat if QT‑interval concerns.
• Signs of tendinopathy: educate patient on sudden pain, swelling in Achilles or other tendons.
• Blood glucose: check prior to dose in diabetes; adjust insulin accordingly.

Clinical Pearls

• Avoid calcium‑rich meals – they chelate ciprofloxacin and reduce absorption by up to 40 %.
• Sublingual dosing is useful for patients with severe nausea or vomiting, but maintain a 30‑min fasting period pre‑dose.
• Use of higher doses in elderly can heighten CNS side effects; start with the lowest effective dose.
• Photo‑reactivity: counsel patients on broad‑spectrum sunscreen and protective clothing; patients should avoid excessive sun or UV exposure for 2 weeks after therapy.
• Combination therapy: when treating MRSA or *Klebsiella pneumoniae* producing ESBLs, consider adding a β‑lactam or vancomycin; however, ciprofloxacin monotherapy is sufficient for most uncomplicated gram‑negative infections.
• Stopping therapy early to prevent *C. difficile*: abrupt discontinuation increases risk; complete the prescribed course unless severe ADRs occur.
• Renal dose adjustment strategy: use the lowest effective dose (e.g., 250 mg q48 h) to maintain therapeutic trough levels while preventing accumulation.
• Drug interactions: avoid concurrent use of divalent/trivalent cations, antacids, or iron supplements within 2 h to prevent chelation and absorption loss.
• Tendon rupture risk: patients on corticosteroids, men ≥60 yrs, or those with recent infections (e.g., flu) have higher risk; warn to seek immediate care if sudden tendon pain occurs.
• Gastrointestinal bleeding: occasionally signal the spread of underlying ulcer disease; evaluate if typical GI ADRs unresponsive to standard measures.

--
• *Authoritative source: U.S. FDA prescribing information for ciprofloxacin (Cipro). Updated pharmacologic data as of June 2024.*