Levofloxacin

Levofloxacin is a fluoroquinolone antibiotic used to treat a variety of infections caused by susceptible bacteria. It is the levo isomer of ofloxacin and has activity against many Gram-negative bacteria and some Gram-positive organisms.

The mechanism of action involves inhibition of bacterial DNA gyrase and topoisomerase IV, enzymes essential for DNA replication and transcription. This leads to disruption of bacterial growth and eventual cell death.

Common indications include community-acquired pneumonia, acute bacterial sinusitis, chronic bronchitis exacerbations, urinary tract infections (including pyelonephritis), and skin and soft tissue infections. It has limited anaerobic activity and is not routinely used for intra-abdominal infections; susceptibility testing and local resistance patterns influence its use.

Levofloxacin is available in oral and intravenous forms, with high oral bioavailability that approaches IV exposure, allowing practical oral therapy in many settings. The drug has a relatively long half-life and is typically dosed once daily. Renal excretion is a major elimination pathway, necessitating dose adjustments in renal impairment. An oral-to-intravenous switch is common when clinically appropriate.

Safety considerations include common adverse effects such as nausea, diarrhea, and headache. Serious risks, which have led to boxed warnings in some regions, include tendinopathy and tendon rupture, peripheral neuropathy, central nervous system effects, QT interval prolongation, and disturbances in glucose levels. Levofloxacin is generally avoided in pregnancy, lactation, and, in many cases, children due to potential effects on developing cartilage; it should be used with caution in the elderly and in individuals with predisposing cardiac or CNS conditions. Clostridioides difficile infection can occur with antibiotic use.

Drug interactions include reduced absorption with concurrent multivalent cations (e.g., antacids, iron, calcium, sucralfate); separate dosing when possible. Caution is advised with other QT-prolonging drugs and with certain anticoagulants; NSAIDs may increase the risk of CNS stimulation or seizures. Prudent use and adherence to local guidelines are encouraged to minimize resistance.