MOXQUIN 400 is a tablet containing 400 milligrams of moxifloxacin hydrochloride. 1 Moxifloxacin is a broad-spectrum fluoroquinolone antibiotic used to treat various bacterial infections in adults, including acute bacterial sinusitis, acute exacerbation of chronic bronchitis, community-acquired pneumonia, uncomplicated and complicated skin and skin structure 2 infections, complicated intra-abdominal infections, and pelvic inflammatory disease. 3 It works by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes essential for bacterial DNA replication, transcription, and repair. 4 The usual dosage is 400 mg once daily, with the duration of treatment depending on the type of infection