CHIBROXIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CHIBROXIN (CHIBROXIN).
Chibroxin (norfloxacin) is a fluoroquinolone antibiotic that inhibits bacterial DNA gyrase and topoisomerase IV, preventing DNA replication and transcription.
| Metabolism | Norfloxacin is metabolized in the liver via glucuronidation and N-acetylation. CYP450 involvement is minimal. |
| Excretion | Renal: 98% as unchanged drug; hepatic: 2% as minor metabolites. Biliary/fecal excretion negligible. |
| Half-life | Terminal elimination half-life: 6-8 hours in adults with normal renal function. Prolonged to 12-24 hours in moderate renal impairment (CrCl 30-50 mL/min) and >24 hours in severe impairment (CrCl <30 mL/min). |
| Protein binding | 30-40% bound to serum proteins (primarily albumin). |
| Volume of Distribution | 0.35-0.45 L/kg, indicating distribution into total body water; limited tissue penetration except in inflamed eyes. |
| Bioavailability | Ocular: approximately 50% systemic absorption after topical administration (via nasolacrimal duct). Oral: not applicable (not orally administered). |
| Onset of Action | Ocular: 30-60 minutes after topical administration for bacterial conjunctivitis. |
| Duration of Action | Ocular: 6-8 hours after single dose; requires 4-6 times daily dosing for continuous effect. |
1-2 drops of 0.3% ophthalmic solution into affected eye(s) every 2 hours while awake for the first 2 days, then every 4 hours for 5-7 days.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No systemic absorption with ophthalmic use; no adjustment required. |
| Liver impairment | No systemic absorption with ophthalmic use; no adjustment required. |
| Pediatric use | 1 drop of 0.3% ophthalmic solution into affected eye(s) every 2-4 hours while awake, up to 4 times daily for 7 days. |
| Geriatric use | Same as adult dosing; monitor for ocular adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CHIBROXIN (CHIBROXIN).
| Breastfeeding | Excretion in breast milk is likely. Safety not established; manufacturer advises discontinue nursing or drug. M/P ratio not available for fleroxacin. Avoid use during breastfeeding due to risk of joint damage in infant. |
| Teratogenic Risk | Chibroxin (fleroxacin) is contraindicated in pregnancy. First trimester: Fluoroquinolones are associated with arthropathy in juvenile animals, and human data are limited; potential teratogenic risk cannot be excluded. Second and third trimesters: Risk of fetal cartilage damage and Achilles tendon rupture; avoid use. Arthropathy risk persists postpartum. |
■ FDA Black Box Warning
Fluoroquinolones, including norfloxacin, may exacerbate muscle weakness in persons with myasthenia gravis. Avoid use in patients with known history of myasthenia gravis.
| Serious Effects |
["Hypersensitivity to norfloxacin or other fluoroquinolones","History of myasthenia gravis","Concurrent use with tizanidine"]
| Precautions | ["Risk of tendinitis and tendon rupture","Exacerbation of myasthenia gravis","Peripheral neuropathy","Central nervous system effects (e.g., dizziness, seizures)","QT prolongation","Hypersensitivity reactions","Photosensitivity"] |
| Food/Dietary | Avoid dairy products (milk, yogurt, cheese) and calcium-fortified juices within 2-4 hours of dose. Take on empty stomach; food, especially high-fat meals, may reduce absorption. Avoid caffeine as norfloxacin may increase its effects. Maintain adequate hydration but avoid excessive grapefruit juice (may interact with CYP450). |
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| Fetal Monitoring | Monitor maternal renal function, hepatic function, and complete blood count. Fetal ultrasound for skeletal development if inadvertent exposure. Monitor infant for signs of arthropathy or tendonitis. |
| Fertility Effects | No specific human data on fertility impairment. Animal studies show no adverse effects on fertility at therapeutic doses. Use in pregnancy may affect fetal cartilage development but no direct effect on fertility. |
| Clinical Pearls | Chibroxin (norfloxacin) is a fluoroquinolone antibiotic primarily used for urinary tract infections and bacterial gastroenteritis. Avoid use in patients under 18 due to cartilage damage risk. Monitor for tendonitis or tendon rupture, especially in elderly and those on corticosteroids. Take on empty stomach with full glass of water; avoid antacids, iron, or zinc within 2-4 hours. Renal dose adjustment required for CrCl <30 mL/min. |
| Patient Advice | Take norfloxacin exactly as prescribed; do not skip doses. · Finish the entire course even if you feel better. · Take each dose with a full glass of water, on an empty stomach (1 hour before or 2 hours after meals). · Avoid taking with dairy products, antacids, iron, or zinc supplements; separate by at least 2-4 hours. · Stop taking and contact doctor if you experience tendon pain, swelling, or rupture. · Avoid driving or operating machinery if you experience dizziness or drowsiness. · Stay well hydrated, especially if treating a urinary tract infection. · Contact doctor if diarrhea persists or becomes severe (possible C. difficile infection). · Do not use in children or adolescents under 18 years. · Use sunscreen and protective clothing to avoid photosensitivity reactions. |