- Like other fluorquinolines, oxifloxacin causes inhibition of DNA gyrase enzyme.
This enzyme causes small cut in double stranded DNA, leads to supercoiling and cause re-ligation of cut ends.DNA gyrase comprises of Aand B subunit,in which A subunit causes small cut in DNA and B subunit is responsible for negative supercoiling followed by re-ligation of A subunit.
- Moxifloxacin attaches to A subunit of DNA gyrase with greater affinity and restrict the function of DNA gyrase enzyme
- The predominant target in vram positive bacteria is an analogous enzyme topoisomerase IV that nicks and separate daughter DNA strand once the DNA replication is complete.
The damaged DNA leas to formation of exonucleases resulting in digestion of DNA and this contributes to bacteriocidal action of moxifloxacin.
Reference: Tripathi K.D., “Essentials of Medical Pharmacology”, Jaypee brothers medical publishers, Seventh edition, New Delhi, page no. 709,711.