OFLOXACIN
Clinical safety rating: caution
Animal studies have proved adverse effects but may be safe for humans
Inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, preventing DNA replication and transcription.
| Metabolism | Hepatic metabolism via cytochrome P450 enzymes (primarily CYP1A2 and CYP3A4); approximately 5-10% metabolized. |
| Excretion | Approximately 70-90% of an oral dose is excreted unchanged in urine via glomerular filtration and tubular secretion; about 4-8% is excreted in feces as unchanged drug and metabolites. |
| Half-life | Terminal elimination half-life is 4-8 hours in adults with normal renal function; prolonged to 20-50 hours in severe renal impairment (CrCl <20 mL/min). |
| Protein binding | Approximately 20-32% bound to serum albumin. |
| Volume of Distribution | Volume of distribution is 1.2-2.0 L/kg, indicating extensive tissue penetration into skin, lungs, kidneys, prostate, and bone. |
| Bioavailability | Oral bioavailability is 95-100%; ophthalmic: negligible systemic absorption (<0.5%). |
| Onset of Action | Oral: peak serum concentrations reached in 1-2 hours; intravenous: immediate; topical ophthalmic: corneal penetration within 30 minutes. |
| Duration of Action | Bactericidal effect lasts 12-24 hours post-dose; standard dosing intervals are 12 hours for systemic infections; tissue concentrations persist for 6-12 hours. |
| Molecular Weight | 361.37 |
400 mg orally or intravenously every 12 hours for 7-14 days; for uncomplicated gonorrhea, 400 mg as a single oral dose.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | CrCl 20-50 mL/min: 200-400 mg every 24 hours; CrCl <20 mL/min: 200 mg every 24 hours; hemodialysis: 200 mg every 24 hours after dialysis. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment; not studied in severe impairment (Child-Pugh C). |
| Pediatric use | Safety and efficacy not established in children <18 years; not recommended due to risk of arthropathy. Use only for specific infections (e.g., inhalational anthrax) under expert guidance. |
| Geriatric use | Start at lower end of dosing range due to age-related renal impairment; monitor renal function and adjust dose accordingly; increased risk of tendon disorders. |
| 1st trimester | Fluoroquinolones are generally avoided in pregnancy due to potential cartilage damage in immature animals. Limited human data show no significant increase in major malformations, but risk cannot be excluded. Use only if benefit outweighs risk. |
| 2nd trimester | Same as t1. Avoid unless necessary; no specific malformation risk identified but concerns remain about fetal bone and cartilage development. |
| 3rd trimester | Avoid near term due to potential neonatal adverse effects (e.g., joint damage, CNS effects). Not recommended for use in pregnant women. |
Clinical note
Chelates with divalent cations (antacids Ca2+ Fe2+) reducing absorption May enhance effects of warfarin Associated with tendonitis and tendon rupture.
| Placental transfer | Ofloxacin crosses the placenta; cord blood concentrations reach 50-70% of maternal serum levels. Clinical significance unknown. |
| Breastfeeding | Ofloxacin is excreted into breast milk in low concentrations (milk/plasma ratio ~0.7-1.0). Maximum relative infant dose is <2% of maternal weight-adjusted dose, considered safe for short-term use. However, theoretical risk of joint damage in nursing infants exists; monitor for diarrhea or candidiasis. The American Academy of Pediatrics considers ofloxacin compatible with breastfeeding. |
■ FDA Black Box Warning
Fluoroquinolones, including ofloxacin, may exacerbate muscle weakness in persons with myasthenia gravis. Avoid use in patients with a history of myasthenia gravis.
| Common Effects | Eye discomfort Nausea Headache Dizziness Itching Insomnia difficulty in sleeping Rash Genital itching Vaginal inflammation Phlebitis Injection site reactions pain swelling redness |
| Serious Effects |
Hypersensitivity to ofloxacin or any fluoroquinoloneHistory of tendon disorders related to fluoroquinolone useChildren and adolescents (<18 years) except for specific approved indications (e.g., anthrax, complicated urinary tract infections)Epilepsy or history of CNS disorders (lowered seizure threshold)Prolonged QT interval or concurrent use of drugs that prolong QT intervalMyasthenia gravis (may exacerbate muscle weakness)
| Precautions | Tendinitis and tendon rupture risk, Peripheral neuropathy, Central nervous system effects including seizures, dizziness, and increased intracranial pressure, Exacerbation of myasthenia gravis, Hypersensitivity reactions, Photosensitivity/phototoxicity, Clostridium difficile-associated diarrhea, Prolongation of QT interval, Blood glucose disturbances |
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| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | Fluoroquinolones, including ofloxacin, are associated with arthropathy in juvenile animals and potential cartilage damage in humans. Use in pregnancy is generally avoided, especially during the first trimester. Ofloxacin is classified as FDA Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. Postmarketing reports suggest a potential for fetal harm, including abortions and malformations, but a definitive causal relationship has not been established. Therefore, ofloxacin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. |
| Fetal Monitoring | Maternal: Renal function, hepatic function, and complete blood count should be monitored periodically, especially during prolonged therapy. Signs of tendonitis or tendon rupture, peripheral neuropathy, and central nervous system effects (e.g., dizziness, seizures) should be assessed. Fetal/Neonatal: Monitor for potential adverse effects such as arthropathy if exposed in utero. Neonates should be observed for signs of jaundice or CNS effects. |
| Fertility Effects | Ofloxacin has not been shown to impair fertility in animal studies. However, fluoroquinolones may affect male fertility by causing reversible sperm abnormalities, such as decreased motility and concentration. Data in humans are limited; caution is advised for men attempting to conceive. |
| Food/Dietary | Avoid taking with dairy products (milk, yogurt, cheese) or calcium-fortified juices as they may reduce absorption. Separate intake of antacids, sucralfate, didanosine chewable/buffered tablets, or mineral supplements (iron, zinc, calcium, magnesium) by at least 2 hours before or after ofloxacin. Caffeine intake may increase stimulant effects; monitor for jitteriness. Grapefruit juice has no significant interaction with ofloxacin. |
| Clinical Pearls | Ofloxacin is a fluoroquinolone with good oral bioavailability and broad-spectrum coverage including atypical pathogens. Reserve for indications where alternatives are limited due to risks of tendonitis, tendon rupture, peripheral neuropathy, CNS effects, and exacerbation of myasthenia gravis. Adjust dose in renal impairment (CrCl <50 mL/min). Avoid in children <18 years except for specific approved uses. Monitor for C. difficile diarrhea. Ofloxacin is a substrate of P-glycoprotein; avoid concurrent NSAIDs due to increased CNS stimulation risk. |
| Patient Advice | Take exactly as prescribed; do not skip doses or stop early even if feeling better. · Take at the same time each day, with or without food. Avoid taking with dairy products, antacids, sucralfate, or iron/zinc supplements within 2 hours. · Drink plenty of fluids to prevent crystal formation in urine. · Stop medication and contact doctor immediately if you experience tendon pain/swelling, numbness/tingling, confusion, hallucinations, rapid heartbeat, or severe diarrhea. · Avoid driving or operating heavy machinery until you know how this medication affects you; may cause dizziness or vision changes. · Do not use for infections other than prescribed; do not share with others. · Store at room temperature away from moisture and heat. |