Pharmacology: Molox belongs to fluoroquinolone class of antibiotics. Moxifloxacin is bactericidal and its mode of action involves inhibition of the enzymes topoisomerase II (DNA gyrase) and topoisomerase IV. DNA gyrase is an essential enzyme that is involved in the replication, transcription and repair of bacterial DNA. Topoisomerase IV is an enzyme known to play a key role in the partitioning of the chromosomal DNA during bacterial cell division. This mechanism is lethal to susceptible bacteria. Moxifloxacin is often referred to as a chemotherapeutic drug because its mode of action has so far not been noted in any natural occurring or semi-synthetic antibiotic.
Pharmacokinetics: Absorption: Moxifloxacin, given as an oral tablet, is well absorbed from the gastrointestinal tract. The absolute bioavailability of Moxifloxacin is approximately 91 percent. Co-administration with a high fat meal (i.e., 500 calories from fat) does not affect the absorption of Moxifloxacin.
Distribution: Moxifloxacin is approximately 45% bound to serum proteins, independent of drug concentration. The volume of distribution of Moxifloxacin ranges from 1.7 to 2.7 L/kg. Moxifloxacin is widely distributed throughout the body, with tissue concentrations often exceeding plasma concentrations. Moxifloxacin has been detected in the saliva, nasal and bronchial secretions, mucosa of the sinuses, skin blister fluid, subcutaneous tissue, skeletal muscle, and abdominal tissues and fluids following oral administration of 400 mg.
Metabolism: Moxifloxacin is metabolized via glucuronide and sulfate conjugation. The sulfate conjugate (M1) accounts for approximately 38% of the dose, and is eliminated primarily in the feces. Approximately 14% of an oral dose is converted to a glucuronide conjugate (M2), which is excreted exclusively in the urine. Peak plasma concentrations of M2 are approximately 40% those of the parent drug, while plasma concentrations of M1 are generally less than 10% those of Moxifloxacin. The sulfate (M1) and glucuronide (M2) conjugates are not microbiologically active.
Elimination: Approximately 45% of an oral dose of Moxifloxacin is excreted as unchanged drug (~20% in urine and ~25% in feces). A total of 96%±4% of an oral dose is excreted as either unchanged drug or known metabolites. The mean (±SD) apparent total body clearance and renal clearance are 12±2.0 L/hr and 2.6±0.5 L/hr, respectively.