LEVAQUIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LEVAQUIN (LEVAQUIN).
Levofloxacin is a fluoroquinolone antibiotic that inhibits bacterial DNA gyrase and topoisomerase IV, enzymes essential for DNA replication, transcription, repair, and recombination.
| Metabolism | Levofloxacin is minimally metabolized (~5%) to desmethyl-levofloxacin and levofloxacin N-oxide. It is primarily excreted unchanged in the urine via glomerular filtration and tubular secretion. |
| Excretion | Primarily renal excretion as unchanged drug (approximately 87% in urine); fecal excretion accounts for <5% as unchanged drug and metabolites; biliary excretion is minimal. |
| Half-life | Terminal elimination half-life is 6-8 hours in patients with normal renal function; prolonged to 48-108 hours in severe renal impairment (CrCl <20 mL/min). |
| Protein binding | Approximately 24-38% bound to serum proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is 1.1-1.5 L/kg, indicating extensive tissue penetration (e.g., lung, skin, bone, urine). |
| Bioavailability | Oral bioavailability is approximately 99% (essentially complete). |
| Onset of Action | Oral: 1-2 hours; Intravenous: immediate (peak plasma levels achieved within 1 hour of infusion). |
| Duration of Action | 12-24 hours for susceptible organisms; clinical effects persist for ~24 hours due to post-antibiotic effect; dosing interval typically 24 hours. |
| Molecular Weight | 361.37 |
| Action Class | Quinolones/ Fluroquinolones |
| Brand Substitutes | Nirliv 500mg Tablet, Cenquin 500mg Tablet, Levocef 500mg Tablet, Levoshan 500mg Tablet, Qulef 500mg Tablet |
LEVAQUIN (levofloxacin) 500 mg orally or intravenously once daily for most infections; 750 mg orally or intravenously once daily for more severe infections or complicated urinary tract infections.
| Dosage form | INJECTABLE |
| Renal impairment | For CrCl 20-49 mL/min: 500 mg load then 250 mg q24h (if standard 500 mg dose) or 750 mg load then 500 mg q48h (if 750 mg dose). For CrCl 10-19 mL/min: 500 mg load then 250 mg q48h (if 500 mg) or 750 mg load then 500 mg q48h (if 750 mg). For hemodialysis or CAPD: 500 mg load then 250 mg q48h. |
| Liver impairment | No specific dose adjustment is recommended for Child-Pugh A, B, or C; levofloxacin is not extensively metabolized, and hepatic impairment does not significantly affect pharmacokinetics. |
| Pediatric use | Not approved for patients <18 years except for inhalational anthrax (post-exposure) and plague: 8 mg/kg (max 250 mg) dose twice daily for 60 days (anthrax) or 10-15 days (plague); children ≥50 kg use adult dose. |
| Geriatric use | No specific dose adjustment for age alone; use caution due to increased risk of tendinitis/tendon rupture, QT prolongation, and CNS effects; adjust dose based on renal function (CrCl). |
| 1st trimester | Avoid; risk of arthropathy based on animal studies, but human data limited. Use only if benefit outweighs risk for serious infections. |
| 2nd trimester | Avoid; potential risk to fetal cartilage and bone development. Use if no safer alternative. |
| 3rd trimester | Avoid; possible fetal toxicity including retinal and auditory nerve damage. Use only for life-threatening infections. |
Clinical note
Comprehensive clinical and safety monograph for LEVAQUIN (LEVAQUIN).
| Placental transfer | Levofloxacin crosses the placenta. Studies show measurable concentrations in fetal plasma and amniotic fluid, approximately 50-80% of maternal serum levels. |
| Breastfeeding | Levofloxacin is excreted into human breast milk in small amounts. Due to potential risk of arthropathy and fluoroquinolone-associated adverse effects in nursing infants, caution is advised. Consider alternatives, especially in infants <2 months or with concurrent illness. Monitor infant for diarrhea, rash, or joint problems. |
■ FDA Black Box Warning
Fluoroquinolones, including levofloxacin, have been associated with an increased risk of tendinitis and tendon rupture in all ages. Risk is increased in patients over 60 years old, those taking corticosteroids, and those with kidney, heart, or lung transplants. Fluoroquinolones may exacerbate muscle weakness in persons with myasthenia gravis; use with caution in patients with known or suspected myasthenia gravis.
| Serious Effects |
Hypersensitivity to levofloxacin or other quinolonesHistory of tendon disorders related to fluoroquinolone useEpilepsy or history of seizures (increased risk of CNS stimulation)Prolonged QT interval or uncorrected electrolyte disturbancesMyasthenia gravis (may exacerbate weakness)
| Precautions | Tendinitis and tendon rupture (including bilateral), Peripheral neuropathy (may be irreversible), Central nervous system effects (dizziness, confusion, seizures, increased intracranial pressure), Exacerbation of myasthenia gravis, Hypersensitivity reactions (including anaphylaxis, Stevens-Johnson syndrome), Clostridioides difficile-associated diarrhea, Phototoxicity/photosensitivity, Blood glucose disturbances (dysglycemia, including hypoglycemia and hyperglycemia), QT prolongation (avoid in patients with known QTc prolongation, electrolyte abnormalities, or on other QT-prolonging drugs), Renal impairment (dose adjustment required), Avoid excessive sunlight/UV exposure |
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| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Levaquin (levofloxacin) is contraindicated in pregnancy. Fluoroquinolones are associated with arthropathy in immature animals and may cause fetal harm. There is no adequate human data; however, based on animal studies, there is a risk of fetal cartilage damage. Use is not recommended in any trimester unless no safer alternative exists. |
| Fetal Monitoring | Monitor for signs of tendinitis or tendon rupture in the mother. For the fetus, no specific monitoring is recommended if used inadvertently, but consider ultrasound for potential skeletal abnormalities if exposure occurs during pregnancy. |
| Fertility Effects | Levaquin has not been associated with adverse effects on fertility in animal studies. There are no adequate human studies; however, fluoroquinolones are not known to impair fertility. |
| Food/Dietary | Avoid concurrent intake of dairy products (milk, yogurt, cheese) and calcium-fortified juices as they can chelate and reduce absorption. Separate administration by at least 2 hours before or after these foods. Caffeine intake should be moderated as levofloxacin may prolong caffeine effects. |
| Clinical Pearls | Monitor for QT prolongation, especially in patients with electrolyte abnormalities or on antiarrhythmics. Avoid in myasthenia gravis due to risk of exacerbation. Use caution in elderly due to increased risk of tendonitis and tendon rupture. Fluoroquinolones may cause peripheral neuropathy; discontinue immediately if symptoms occur. Levaquin is not first-line for uncomplicated UTIs due to resistance and adverse effects. |
| Patient Advice | Take exactly as prescribed; complete full course even if you feel better. · Avoid taking with dairy products (milk, yogurt) or calcium-fortified juices; take 2 hours before or after. · Drink plenty of fluids to prevent crystal formation in urine. · Report any tendon pain, swelling, or rupture, especially in the Achilles tendon. · Notify your doctor if you experience numbness, tingling, or weakness in limbs. · Avoid sun exposure and use sunscreen; may cause photosensitivity. · Do not take with antacids containing magnesium or aluminum, sucralfate, or iron/zinc supplements. · Seek immediate help if you have palpitations, fainting, or signs of allergic reaction. |