CIPROFLOXACIN
Clinical safety rating: caution
Chelates with divalent cations (antacids Ca2+ Fe2+) reducing absorption May enhance effects of warfarin Associated with tendonitis and tendon rupture.
Inhibits DNA gyrase (topoisomerase II) and topoisomerase IV, preventing bacterial DNA replication, transcription, and repair.
| Metabolism | Hepatic metabolism via CYP1A2; also undergoes renal tubular secretion and glomerular filtration. |
| Excretion | Renal (50-70% unchanged via glomerular filtration and tubular secretion); fecal (15-25% via biliary and transintestinal elimination); <1% as metabolites |
| Half-life | 4 hours (3-5 hours) in normal renal function; prolonged to 8-12 hours in moderate renal impairment (CrCl 20-50 mL/min) and 12-24 hours in severe impairment (CrCl <20 mL/min) |
| Protein binding | 20-40% (primarily to albumin) |
| Volume of Distribution | 2.0-3.5 L/kg (wide distribution into tissues, including lung, skin, bone, urine, and prostate but low CSF penetration unless inflamed) |
| Bioavailability | Oral: 70-80% (decreased by 25-30% when taken with food containing calcium, iron, or zinc; increased by antacids? Actually decreased absorption with multivalent cations); IV: 100% |
| Onset of Action | Oral: 30-60 minutes; Intravenous: within 30 minutes; Topical (ophthalmic/otic): 15-30 minutes |
| Duration of Action | 12 hours for most infections; bactericidal effect persists for 1-2 hours after serum concentrations fall below MIC (due to post-antibiotic effect) |
| Molecular Weight | 331.4 |
400 mg IV every 12 hours or 500 mg orally every 12 hours for uncomplicated infections; 400 mg IV every 8 hours or 750 mg orally every 12 hours for severe/complicated infections.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-50 mL/min: 250-500 mg orally every 12 hours or 200-400 mg IV every 12 hours. CrCl 5-29 mL/min: 200-400 mg orally every 18-24 hours or 200-400 mg IV every 18-24 hours. Hemodialysis: 200-400 mg orally every 24 hours (post-dialysis). CAPD: same as hemodialysis. CRRT: 200-400 mg IV every 12 hours. |
| Liver impairment | No dosage adjustment required for mild-to-moderate hepatic impairment (Child-Pugh A or B). Not studied in severe impairment (Child-Pugh C); use with caution. |
| Pediatric use | 10-20 mg/kg IV every 8 hours (max 400 mg/dose) or 10-20 mg/kg orally every 8 hours (max 750 mg/dose); maximum daily dose 1200 mg for IV and 2250 mg for oral, based on indication. |
| Geriatric use | No specific geriatric dose adjustment; initiate at lower end of dosing range due to age-related renal function decline; adjust based on creatinine clearance. |
| 1st trimester | Avoid; associated with arthropathy in animal studies and potential cartilage damage. |
| 2nd trimester | Avoid; same risks as t1; use only if benefit outweighs risk. |
| 3rd trimester | Avoid; same risks as t1 and t2; potential for fetal cartilage damage. |
Clinical note
Chelates with divalent cations (antacids Ca2+ Fe2+) reducing absorption May enhance effects of warfarin Associated with tendonitis and tendon rupture.
| FDA category | Animal |
| Placental transfer | Ciprofloxacin crosses the placenta; fetal concentrations reach approximately 50-100% of maternal serum levels. |
| Breastfeeding | Ciprofloxacin is excreted into breast milk in small amounts. The American Academy of Pediatrics considers it compatible with breastfeeding, but caution is advised due to potential adverse effects on infant cartilage. Use only if no alternative is available. |
■ FDA Black Box Warning
Fluoroquinolones increase the risk of tendinitis and tendon rupture, especially in patients over 60, those taking corticosteroids, and organ transplant recipients. Avoid use in patients with a history of tendon disorders.
| Common Effects | Nausea |
| Serious Effects |
Hypersensitivity to ciprofloxacin or any fluoroquinoloneConcomitant administration with tizanidine
| Precautions | Exacerbation of myasthenia gravis; peripheral neuropathy; CNS effects (seizures, dizziness); QT prolongation; phototoxicity; Clostridioides difficile-associated diarrhea; hypoglycemia; risk of aortic aneurysm/dissection; increased intracranial pressure; hypersensitivity reactions. |
| Food/Dietary | Avoid concomitant consumption of dairy products (milk, yogurt, cheese) and calcium-fortified foods/juices as they can chelate ciprofloxacin and reduce absorption. Administer ciprofloxacin at least 2 hours before or after meals high in calcium. Caffeine intake should be monitored as ciprofloxacin inhibits its metabolism, potentially leading to increased caffeine effects (e.g., nervousness, insomnia). No significant interaction with alcohol, but alcohol may exacerbate CNS side effects. |
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| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | Ciprofloxacin is contraindicated in pregnancy due to arthropathy risk in animal studies and potential cartilage damage in human neonates. First trimester: limited data suggest no increased major malformations; however, avoid due to theoretical risk. Second/third trimester: associated with fetal cartilage damage and arthropathy; avoid. FDA Pregnancy Category C. |
| Fetal Monitoring | Monitor maternal renal function, hepatic function, and signs of tendinitis or tendon rupture. For fetus, no specific monitoring; avoid use unless benefit outweighs risk. Ultrasound for fetal growth and development if exposure occurs. |
| Fertility Effects | Animal studies show no significant impairment of fertility at clinically relevant doses. Human data limited; no known effect on fertility in males or females. |
| Clinical Pearls | Ciprofloxacin is a potent fluoroquinolone with broad-spectrum activity against Gram-negative bacteria, including Pseudomonas aeruginosa. Avoid use in pediatric patients <18 years due to risk of arthropathy, except for specific indications like anthrax or complicated UTI. Monitor for tendonitis or tendon rupture, especially in patients >60 years, on corticosteroids, or with renal impairment. Ciprofloxacin can prolong QTc interval; avoid in patients with known QTc prolongation, electrolyte imbalances, or concurrent use of other QTc-prolonging drugs. It inhibits CYP1A2, increasing levels of theophylline, tizanidine, and caffeine. Administer at least 2 hours after antacids, sucralfate, or iron/zinc supplements due to chelation. Adjust dose in renal impairment (CrCl <30 mL/min). |
| Patient Advice | Take ciprofloxacin exactly as prescribed, at the same time each day, with or without food. · Avoid taking this medicine with dairy products (milk, yogurt) or calcium-fortified juices as they may reduce absorption. · Drink plenty of fluids to stay hydrated and prevent crystal formation in urine. · Do not take antacids, sucralfate, iron supplements, or zinc supplements within 2 hours of ciprofloxacin. · Stop taking the medication and call your doctor immediately if you experience tendon pain, swelling, or rupture, especially in the Achilles tendon. · Report any symptoms of peripheral neuropathy such as pain, burning, tingling, numbness, or weakness. · Ciprofloxacin can cause dizziness or lightheadedness; avoid driving or operating machinery until you know how the drug affects you. · Avoid excessive sun exposure and use sunscreen; ciprofloxacin can increase sensitivity to sunlight. · Inform your doctor if you have a history of seizures, QT prolongation, or if you are taking medications like theophylline, tizanidine, or warfarin. · Complete the full course of therapy even if you feel better to prevent resistance. |