Indications
Moxifloxacin is a versatile fluoroquinolone antibiotic indicated for the treatment of various bacterial infections. It is commonly prescribed for conditions such as sinusitis, pneumonia, and secondary infections in chronic bronchitis. Additionally, Moxifloxacin is effective in the treatment of bacterial conjunctivitis, also known as pinkeye.
Pharmacodynamics
Moxifloxacin exerts its therapeutic effects as a broad-spectrum antibiotic that targets a wide range of bacterial pathogens. It is effective against aerobic Gram-positive microorganisms, including various species of Corynebacterium and Staphylococcus, as well as Streptococcus pneumoniae and the Streptococcus viridans group. The drug also demonstrates activity against aerobic Gram-negative microorganisms like Acinetobacter lwoffii and Haemophilus species, in addition to other pathogens such as Chlamydia trachomatis. Mechanistically, Moxifloxacin is bactericidal, achieving its effects by inhibiting bacterial DNA replication. It binds to the bacterial enzyme DNA gyrase, preventing the untwisting of DNA required for replication. Importantly, Moxifloxacin has a 100 times higher affinity for bacterial DNA gyrase compared to mammalian counterparts, enhancing its specificity and effectiveness.
Absorption
Moxifloxacin is characterized by excellent absorption from the gastrointestinal tract, with an absolute oral bioavailability of approximately 90%. The presence of food has minimal impact on the drug's absorption, allowing for convenient dosing without strict regard to meals.
Metabolism
In terms of metabolism, roughly 52% of an administered oral or intravenous dose of Moxifloxacin is metabolized by conjugation processes, namely glucuronide and sulphate conjugation. Notably, the cytochrome P450 enzyme system is not involved in its metabolism. The sulphate conjugate constitutes approximately 38% of the dose, while the glucuronide conjugate makes up about 14%.
Mechanism of Action
Moxifloxacin exerts its bactericidal effects by inhibiting the activity of two critical bacterial enzymes: topoisomerase II (DNA gyrase) and topoisomerase IV. DNA gyrase is vital for several cellular processes, including the replication, transcription, and repair of bacterial DNA. Meanwhile, topoisomerase IV is integral to the separation of chromosomal DNA during bacterial cell division. By targeting these enzymes, moxifloxacin effectively disrupts essential bacterial DNA processes, leading to the eradication of bacterial cells.
