Levofloxacin is a broad-spectrum, third-generation fluoroquinolone antibiotic used to treat bacterial infections. Levofloxacin is a safe and effective medicine on the World Health Organization's essential medicines list. It was patented in 1987 and subsequently received FDA-approval in 1996 for medical use in the United States.[1]

Levofloxacin is FDA-approved for the treatment of nosocomial pneumonia, community-acquired pneumonia, acute bacterial rhinosinusitis, acute bacterial exacerbation of chronic bronchitis, prostatitis, acute pyelonephritis, urinary tract infection (uncomplicated or complicated), skin or skin structure infections, prophylaxis and treatment of plague due to Yersinia pestis, and to reduce the incidence of disease progression of inhalational anthrax. Due to an increased risk of severe side effects (e.g., tendinitis and tendon rupture, peripheral neuropathy, and CNS effects), levofloxacin is used only in patients with acute exacerbation of chronic bronchitis, acute bacterial sinusitis, and uncomplicated urinary tract infections, who do not have alternative treatment options. Ophthalmic levofloxacin also has a use in the treatment of bacterial conjunctivitis. To decrease the development of drug-resistant bacteria, the FDA has recommended using levofloxacin only for strongly suspected bacterial infections. Also, levofloxacin should not be used empirically in patients at risk of multidrug-resistant Escherichia coli.[2] 

Levofloxacin is a bactericidal antibiotic of the fluoroquinolone drug class that directly inhibits bacterial DNA synthesis. Levofloxacin promotes the breakage of DNA strands by inhibiting DNA-gyrase in susceptible organisms, which in turn inhibits the relaxation of supercoiled DNA. Of the fluoroquinolone class, levofloxacin has the most enhanced activity against gram-positive penicillin-sensitive and resistant organisms notably, Streptococcus pneumoniae), and reduced action against gram-negative bacilli notably, Pseudomonas aeruginosa compared to ciprofloxacin. Levofloxacin has effectiveness against other common respiratory organisms; notably, Haemophilus influenzae, Moraxella catarrhalis, Legionella spp, Mycoplasma spp, and Chlamydia pneumoniae.[2] Levofloxacin also has a higher in-vitro activity against Mycobacterium tuberculosis and is preferred over the other fluoroquinolones as second-line antitubercular therapy.[3] There is a growing concern of drug resistance to fluoroquinolones worldwide, which can occur through chromosome-encoded or plasmid-mediated mechanisms. Levofloxacin is rapidly absorbed and widely distributed in the body. The bioavailability of levofloxacin is 99%; therefore, the intravenous and oral preparations of levofloxacin are usable interchangeably. Levofloxacin clearance is primarily via the renal route (87%).[4]

Levofloxacin is available both for oral tablets and solution, and intravenous administration. Levofloxacin is not available for administration through intramuscular, intrathecal, or subcutaneous routes. The available oral dosage strengths for levofloxacin are 250 mg, 500 mg, and 750 mg.

Oral dosing with tablets can be without regard to meals. However, the oral solution should be taken 1 hour before or 2 hours after meals. Patients should avoid using antacids, or levofloxacin should be administered two hours before or two hours after taking antacids containing magnesium or aluminum. It is essential to maintain proper hydration to prevent crystalluria.  

The recommended oral dose regimen is 750 mg once daily to treat nosocomial pneumonia, complicated skin and skin structure infections (7 to 14 days), community-acquired pneumonia, acute bacterial sinusitis, complicated urinary tract infection or acute pyelonephritis (five days). The daily dosing of 500 mg once daily is recommended to treat nosocomial pneumonia (7 to 14 days), acute bacterial sinusitis (10 to 14 days), acute bacterial exacerbation of chronic bronchitis (seven days), uncomplicated skin and skin structure infections (7 to 10 days), chronic bacterial prostatitis (28 days), and post-exposure inhalational anthrax (60 days). The daily dosing of 250 mg once daily is recommended for patients with complicated urinary tract infections or acute pyelonephritis (10 days) or uncomplicated urinary tract infections (3 days).[1] 

Levofloxacin injection should be administered to both adult or pediatric patients by slow intravenous infusion over 60 minutes (for 250 to 500 mg) and over 90 minutes (for 750 mg). Due to an increased risk of hypotension, bolus or rapid intravenous administration should be avoided. The infusion should not use a solution containing multivalent cations. The ophthalmic solution is safe and an effective antibiotic used for seven days in the treatment of bacterial conjunctivitis. 

A 50% reduction in the total daily dosage is recommended in patients with renal impairment (glomerular filtration rate between 10 and 50 mL/min) and extended to every 48 hours if glomerular filtration rate falls less than 10 mL/min).[1]

The primary adverse effects of levofloxacin include photosensitivity, nausea, diarrhea, headache, tendinitis, tendon rupture, hyper-hypoglycemia, seizures, prolonged QT interval, and peripheral neuropathy.[5] Clinicians should prescribe levofloxacin to patients with a history of a prolonged QT interval carefully. It is advisable to minimize or avoid exposure to natural or artificial sunlight while taking levofloxacin to reduce the occurrence of phototoxicity. FDA has alerted a black box warning for using levofloxacin and other fluoroquinolones due to increased risk of disabling and irreversible side effects, including tendinitis and tendon rupture, peripheral neuropathy, and CNS effects (e.g., seizures, increased intracranial pressure) in all ages.[6] However, older patients (older than 60 years), those patients taking corticosteroids and with kidney, heart, or lung transplants are at increased risk of severe tendon disorders. Research has determined that prolonged use of levofloxacin is associated with increased risk of fungal or bacterial superinfection (e.g., pseudomembranous colitis).[7] Due to the increased risk of hepatotoxicity, patients should be educated on signs or symptoms of liver injury so they can discontinue treatment. 

The concurrent administration of levofloxacin with drugs that prolong the QT interval is contraindicated. It is also contraindicated in patients with documented hypersensitivity to the drug or its components, in pregnancy, nursing mothers, and in children younger than 18 years of age due to possible risk of cartilage damage. It is a recommendation to avoid levofloxacin and other fluoroquinolone antibiotics in patients with myasthenia gravis due to an increased risk of exacerbating existing muscle weakness. Unlike ciprofloxacin, levofloxacin does not inhibit drug-metabolizing enzyme CYP1A2; however, due to its weak inhibiting potential on CYP2C9 enzyme, bleeding can occur with concurrent administration of warfarin.[8] Careful monitoring of blood glucose is recommended for patients taking concurrent antidiabetic agents due to the risk of glucose dysregulation.