Pharmacology: Pharmacodynamics: Mechanism of action: Moxifloxacin is an 8-methoxy fluoroquinolone antibiotic that inhibits topoisomerases II and IV, which control DNA topology and assist in DNA replication, repair and transcription. It has activity against a wide range of aerobic gram-positive and gram-negative microorganisms.
Pharmacokinetics: Moxifloxacin is well absorbed from the GI tract and absolute bioavailability is 86 - 92%. Peak plasma concentrations are attained within 0.5 - 4 hours; steady state is attained after at least 3 days. Moxifloxacin is widely distributed into body tissues and fluids, including saliva, nasal and bronchial secretions, sinus mucosa, skin blister fluid, subcutaneous tissue, skeletal muscle, and abdominal tissues and fluids. The drug is distributed into milk in rats and may be distributed into human milk. Moxifloxacin is 30 - 50% bound to plasma proteins. Approximately 52% of an oral dose of moxifloxacin is metabolized via glucuronide and sulfate conjugation; the metabolites are not microbiologically active. Moxifloxacin is not metabolized by cytochrome P-450 (CYP) isoenzymes. Moxifloxacin is eliminated in urine and by biliary excretion and metabolism. Approximately 45% of an oral dose of drug is excreted unchanged (20% in urine and 25% in feces). A total of 96% of an oral is excreted as unchanged drug or metabolites. Mean half-life of moxifloxacin is 11.5 - 15.6 hours following single or multiple oral doses.