Gatifloxacin - How It Works
Clinical pharmacology details from the US FDA-approved label: how Gatifloxacin works in your body, how it's absorbed, how long it stays active, and how it's eliminated.
Mechanism of Action
12.1 Mechanism of Action Gatifloxacin is a quinolone antimicrobial [see Microbiology ].
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Gatifloxacin is a quinolone antimicrobial [see Microbiology ].
12.3 Pharmacokinetics Gatifloxacin ophthalmic solution 0.5% was administered to one eye of 6 healthy male subjects each in an escalated dosing regimen starting with a single 2 drop dose, then 2 drops 4 times daily for 7 days, and finally 2 drops 8 times daily for 3 days.
At all time points, serum gatifloxacin levels were below the lower limit of quantification (5 ng/mL) in all subjects.
12.4 Microbiology Gatifloxacin is an 8-methoxyfluoroquinolone with a 3-methylpiperazinyl substituent at C7.
The antibacterial action of gatifloxacin results from inhibition of 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.
The mechanism of action of fluoroquinolones including gatifloxacin is different from that of aminoglycoside, macrolide, and tetracycline antibiotics.
Therefore, gatifloxacin may be active against pathogens that are resistant to these antibiotics and these antibiotics may be active against pathogens that are resistant to gatifloxacin.
There is no cross-resistance between gatifloxacin and the aforementioned classes of antibiotics.
Cross-resistance has been observed between systemic gatifloxacin and some other fluoroquinolones.
Resistance to gatifloxacin in vitro develops via multiple-step mutations.
Resistance to gatifloxacin in vitro occurs at a general frequency of 1 x 10 -7 to 10 -10 .
Gatifloxacin has been shown to be active against most isolates of the following organisms both microbiologically and clinically, in conjunctival infections: Aerobic gram-positive bacteria: Staphylococcus aureus Staphylococcus epidermidis Streptococcus mitis group* Streptococcus oralis* Streptococcus pneumoniae Aerobic gram-negative bacteria: Haemophilus influenzae * Efficacy for these organisms were studied in fewer than 10 infections.
Pharmacokinetics
12.3 Pharmacokinetics Gatifloxacin ophthalmic solution 0.5% was administered to one eye of 6 healthy male subjects each in an escalated dosing regimen starting with a single 2 drop dose, then 2 drops 4 times daily for 7 days, and finally 2 drops 8 times daily for 3 days. At all time points, serum gatifloxacin levels were below the lower limit of quantification (5 ng/mL) in all subjects.