Topoisomerase II (IC50 = 36.7 μM)

Gatifloxacin hydrochloride targets Staphylococcus aureus MS5935 topoisomerase IV, Escherichia coli NIHJ JC-2 DNA gyrase and HeLa cell topoisomerase II, having IC50 values of 13.8 μg/ml and 0.109 μg/ml respectively. and 265 μg/ml [1]. Gatifloxacin hydrochloride targets Staphylococcus aureus MS5935 topoisomerase IV, Escherichia coli NIHJ JC-2 DNA gyrase and HeLa cell topoisomerase II, with MIC values of 0.05 μg/ml, 0.0063 μg/ml and 122 respectively. μg/ml[1]. Gatifloxacin hydrochloride exhibits antibacterial activity against wild-type strains (MS5935, MS5952, MR5867 and MR6009), step one, step two, step three and step four mutants with MIC values of 0.05 to 0.10 μg/ml , 0.20 μg/ml, 1.56 to 3.13 μg/ml, 1.56 to 6.25 μg/ml and 50 to 200 μg/ml respectively. Except for the second-step mutant of strain MS5935, gatifloxacin hydrochloride demonstrated the most powerful efficacy against the second- and third-step mutants (MS5952, MR5867, and MR6009) [2]. Gatifloxacin hydrochloride has potent activity against norA transformant NY12 (MIC, 0.39 μg/ml) [2]. Gatifloxacin hydrochloride (20-100 μM; 72 hours) significantly reduced insulin content to 60% on day 1 and continued on day 3 to 50.1% and 50.1% by 20 μM and 100 μM gatifloxacin hydrochloride, respectively. 44.7%[3].

In mice infected with Nocardia brasiliensis, gatifloxacin hydrochloride (subcutaneous injection; 100 mg/kg; three times daily; thirty days) dramatically decreased the frequency of footpad lesions [4]. Gatifloxacin(subcutaneous injection; 100 mg/kg; three times daily; thirty days) dramatically reduces the number of lesion in mouse footpad with Nocardia brasiliensis[4].
Gatifloxacin at 100 mg/kg maintained plasma levels over the MIC of N. brasiliensis HUJEG-1 (0.25 μg/ml) for more than 4 h, reaching a maximum concentration in serum of 18 μg/ml (Fig. 1). Linezolid at 25 mg/kg also kept concentrations above the MIC (0.12 μg/ml) for more than 4 h, with a maximum concentration in serum of 50 μg/ml. Given these results, we decided to use gatifloxacin at 100 mg/kg three times daily, injected subcutaneously, and linezolid also three times per day at 25 mg/kg. In Fig. 2, the effect of gatifloxacin on the development of the lesions is shown. The animals showed a decrease in the number of lesions, comparable to the effect of linezolid. When the results were analyzed with the one-way analysis of variance test, both treatments, either with linezolid or with gatifloxacin, were statistically significant with a P value of 0.001 compared with the group of animals injected with saline. [4]

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Effect of gatifloxacin withdrawal on insulin secretion and islet insulin content [3]
Mouse pancreatic islets were cultured in the presence of 20 or 100 μM gatifloxacin for one day, washed thoroughly with gatifloxacin-free RPMI medium, and cultured for an additional two days in the gatifloxacin-free medium. Glucose-induced insulin secretion was greatly decreased by gatifloxacin treatment, but recovered after removal of gatifloxacin from the culture medium (Fig. 5A). Islet insulin content was decreased by gatifloxacin similarly, while frequently recovering by withdrawal of gatifloxacin in the 20 μM gatifloxacin group (to 77% of control (0 μM Gatifloxacin)) and not at all in the 100 μM gatifloxacin group (Fig. 5B). Since culture in the presence of gatifloxacin lowers islet insulin content, insulin secretion was expressed as % content, and insulin release from islets cultured with both 20 μM gatifloxacin and 100 μM gatifloxacin showed almost complete recovery upon discontinuation of the drug (Fig. 5C).

The bacterial enzymes DNA gyrase and topoisomerase IV are inhibited by the antibiotic gatifloxacin, which belongs to the fourth generation fluoroquinolone family.

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Enzyme assay. [1]
The decatenation activity of the reconstituted topoisomerase IV was determined by the method of Peng and Marians with minor modifications. The reactions were analyzed by electrophoresis, and DNA quantification in agarose gels was carried out after ethidium bromide staining. The brightness of the bands corresponding to decatenated monomers of kinetoplast DNA was determined by densitometric analysis with FMBIO II Multi-View. The supercoiling activity of DNA gyrase was determined by the method of Gellert et al. with minor modifications. Analysis was performed as described for the topoisomerase IV assay. The relaxation activity of topoisomerase II was determined by the method of Oomori et al. The inhibitory effect of each quinolone on type II topoisomerase was assayed by determining the concentration required to inhibit 50% of the enzyme reaction (IC50). Selectivity was determined by dividing the IC50 for HeLa cell topoisomerase II by the IC50 for bacterial type II topoisomerase.

Antimicrobial Like other members of the fourth-generation fluoroquinolone family of antibiotics, gatifloxacin inhibits the bacterial enzymes DNA gyrase and topoisomerase IV. When it came to the second-step mutants (grlA gyrA; gatifloxacin MIC range, 1.56 to 3.13 microg/ml) and the third-step mutants (grlA gyrA grlA; gatifloxacin MIC range, 1.56 to 6.25 microg/ml), gatifloxacin exhibited activity comparable to that of tosufloxacin and more potent than those of norfloxacin, ofloxacin, ciprofloxacin, and sparfloxacin. These results suggest that gatifloxacin has the most potent inhibitory activity against singly mutated topo IV and singly mutated DNA gyrase among the quinolones studied. In the case of Pseudomonas aeruginosa-infected corneal ulcers, ophthalmic gatifloxacin 0.3% is at least as effective as ciprofloxacin when given less frequently. Fluorescein retention scores showed a trend favoring gatifloxacin.

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Analysis of mouse insulin-2 mRNA from cultured islets and MIN6 cells [3]
After groups of 50 islets were cultured with or without gatifloxacin for 3 days, poly(A)+ RNAs were isolated using a Poly(A)Pure kit and first strand cDNAs were synthesized by SuperScript™ II Reverse Transcriptase system according to the manufacturer's instructions. TaqMan™ quantitative polymerase chain reaction (PCR) assay for mouse Insulin-2 (mIns-2) was performed using forward and reverse mIns-2-specific primers and probes in an ABI PRISM™ 7000 Sequence Detection System. The results are expressed as the ratio of mIns-2 mRNA to mouse Glyceraldehydes-3-phosphate dehydrogenase (GAPDH) mRNA. MIN6 cells were cultured in Dulbecco's Minimal Essential Medium supplemented with 25 mM glucose and 13% fetal bovine serum with or without gatifloxacin for 3 days. Total RNA (10 μg) prepared with TRIzol reagent was used for Northern blot analysis. Mouse β-actin mRNA was used for standardization. Insulin promoter activity was evaluated in MIN6 cells transfected with the human insulin promoter-luciferase reporter gene and cultured for three days with or without 100 μM gatifloxacin, using Dual-Luciferase Reporter Assay System according to manufacture's instructions. Mean values of luciferase activity relative to the gatifloxacin-untreated control were calculated from duplicate wells.

Animal/Disease Models: Female balb/c (Bagg ALBino) mouse, infected with Nocardia brasiliensis on the right hind footpad [1]
Doses: 100 mg/kg
Route of Administration: subcutaneous injection; 3 times a day; 30-day
Experimental Results: diminished mouse injuries of production.

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Isolation of mouse pancreatic islets and islet culture [3]
Pancreatic islets were isolated from fed male C57Bl/6 mice aged 12–16 weeks by collagenase digestion method. For short term exposure, fresh islets were used. For long term exposure, islets were cultured with or without gatifloxacin in RPMI medium containing 10% fetal bovine serum and 11.1 mM glucose, and used after the indicated culture periods for subsequent experiments. In some experiments (Fig. 5), the islets were cultured in the presence of 20 or 100 μM gatifloxacin for one day, washed with gatifloxacin-free RPMI medium three times to remove remaining gatifloxacin in the culture medium, and then cultured for additional two days in gatifloxacin-free medium.

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For the animal assays, we utilized Nocardia brasiliensis HUJEG-1, which has been utilized in previous studies. The MICs of this strain, determined by the broth microdilution method, are 0.25 μg/ml for gatifloxacin and 0.12 μg/ml for linezolid. For the determination of the plasma levels of gatifloxacin and linezolid, several doses of these compounds were used. Linezolid was used at 10 mg/kg body weight, 25 mg/kg, and 50 mg/kg, and gatifloxacin at 50 mg/kg, 75 mg/kg, and 100 mg/kg. Eight- to 12-week-old female BALB/c mice were injected subcutaneously with the antimicrobials. For each dose tested, 27 mice were utilized; 24 were injected with the selected dose, and 3 mice were not injected to represent time zero. Next, 500-μl blood samples were taken from the infraorbital sinus of each mouse, which previously had undergone general anesthesia with ethylic ether. The samples were taken from groups of three mice each at the following time intervals: 0 min, 20 min, 40 min, 1 h, 2 h, 4 h, 6 h, 8 h, and 10 h. After sample collection, the plastic tubes containing the blood were centrifuged and the plasma was separated and frozen at −70°C. Plasma concentrations were determined by using a previously validated high performance liquid chromatography method. For the therapeutic assays, 8- to 12-week-old female BALB/c mice were inoculated with 20 mg of Nocardia brasiliensis in the right hind footpad. Seven days later, the therapeutic assay was started. Groups of 15 mice each were used. One group was injected subcutaneously in the back with 0.1 ml of pyrogen-free saline; the rest were treated with either gatifloxacin at 100 mg/kg or linezolid at 25 mg/kg. All the treatments, including the saline solution, were given subcutaneously on the back three times per day during a 4-week period. The development of lesions in the footpad of the animals was scored by two independent readers as described previously. This system classifies the lesions from those animals presenting absolutely no lesions or inflammation as negative or zero and the lesions from animals presenting severe lesions extending above the metatarsal bones as 4+. Differences among the therapeutic groups were analyzed using the analysis of variance test and confirmed with the Dunnet analysis. [4]

Absorption, Distribution and Excretion
Well absorbed from the gastrointestinal tract after oral administration with absolute bioavailability of gatifloxacin is 96%

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Metabolism / Metabolites
Gatifloxacin undergoes limited biotransformation in humans with less than 1% of the dose excreted in the urine as ethylenediamine and methylethylenediamine metabolites
Gatifloxacin undergoes limited biotransformation in humans with less than 1% of the dose excreted in the urine as ethylenediamine and methylethylenediamine metabolites
Half Life: 7-14 hours

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Biological Half-Life
7-14 hours

Toxicity Summary
The bactericidal action of Gatifloxacin results from inhibition of the enzymes topoisomerase II (DNA gyrase) and topoisomerase IV, which are required for bacterial DNA replication, transcription, repair, and recombination.

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the clinical use of gatifloxacin during breastfeeding. Fluoroquinolones have traditionally not been used in infants because of concern about adverse effects on the infants' developing joints. However, recent studies indicate little risk. The calcium in milk might prevent absorption of the small amounts of fluoroquinolones in milk, but insufficient data exist to prove or disprove this assertion. Use of gatifloxacin is acceptable in nursing mothers with monitoring of the infant for possible effects on the gastrointestinal flora, such as diarrhea or candidiasis (thrush, diaper rash). However, it is preferable to use an alternate drug for which safety information is available.
Maternal use of an ear drop or eye drop that contains gatifloxacin presents negligible risk for the nursing infant. To substantially diminish the amount of drug that reaches the breastmilk after using eye drops, place pressure over the tear duct by the corner of the eye for 1 minute or more, then remove the excess solution with an absorbent tissue.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
20%

[1]. Inhibitory activities of gatifloxacin (AM-1155), a newly developed fluoroquinolone, against bacterial and mammalian type II topoisomerases.Antimicrob Agents Chemother. 1998 Oct;42(10):2678-81.

[2]. Antibacterial activity of gatifloxacin (AM-1155, CG5501, BMS-206584), a newly developed fluoroquinolone, against sequentially acquired quinolone-resistant mutants and the norA transformant of Staphylococcus aureus. Antimicrob Agents Chemother. 1998 Aug;42(8):1917-22.

[3]. Gatifloxacin acutely stimulates insulin secretion and chronically suppresses insulin biosynthesis. Eur J Pharmacol. 2006 Dec 28;553(1-3):67-72.

[4]. In vivo therapeutic effect of gatifloxacin on BALB/c mice infected with Nocardia brasiliensis. Antimicrob Agents Chemother. 2008 Apr;52(4):1549-50.

Gatifloxacin is a monocarboxylic acid that is 4-oxo-1,4-dihydroquinoline-3-carboxylic acid which is substituted on the nitrogen by a cyclopropyl group and at positions 6, 7, and 8 by fluoro, 3-methylpiperazin-1-yl, and methoxy groups, respectively. Gatifloxacin is an antibiotic of the fourth-generation fluoroquinolone family, that like other members of that family, inhibits the bacterial topoisomerase type-II enzymes. It has a role as an antiinfective agent, an EC 5.99.1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor and an antimicrobial agent. It is a quinolinemonocarboxylic acid, a N-arylpiperazine, an organofluorine compound, a quinolone and a quinolone antibiotic.
Gatifloxacin is an antibiotic agent and a member of the fourth-generation fluoroquinolone family. It works by inhibiting the bacterial enzymes DNA gyrase and topoisomerase IV. It was first introduced by Bristol-Myers Squibb in 1999 under the brand name Tequin® for the treatment of respiratory tract infections. Gatifloxacin is available as tablets and in various aqueous solutions for intravenous therapy. It is also available as eye drops under the brand name Zymar® marketed by Allergan. The FDA withdrew its approval for the use of non-ophthalmic drug products containing gatifloxacin due to the high prevalence of gatifloxacin-associated dysglycemia adverse event reports and the high incidence of hyperglycemic and hypoglycemic episodes in patients taking gatifloxacin compared to those on macrolide antibiotics.
Gatifloxacin anhydrous is a Quinolone Antimicrobial.
Gatifloxacin is a synthetic 8-methoxyfluoroquinolone with antibacterial activity against a wide range of gram-negative and gram-positive microorganisms. Gatifloxacin exerts its effect through inhibition of DNA gyrase, an enzyme involved in DNA replication, transcription and repair, and inhibition of topoisomerase IV, an enzyme involved in partitioning of chromosomal DNA during bacterial cell division.
Gatifloxacin is an antibiotic of the fourth-generation fluoroquinolone family, that like other members of that family, inhibits the bacterial enzymes DNA gyrase and topoisomerase IV. Bristol-Myers Squibb introduced Gatifloxacin in 1999 under the proprietary name Tequin™ for the treatment of respiratory tract infections, having licensed the medication from Kyorin Pharmaceutical Company of Japan. Allergan produces an eye-drop formulation called Zymar™. Gatifloxacin is available as tablets and in various aqueous solutions for intravenous therapy. [Wikipedia]
A fluoroquinolone antibacterial agent and DNA TOPOISOMERASE II inhibitor that is used as an ophthalmic solution for the treatment of BACTERIAL CONJUNCTIVITIS.

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Drug Indication
For the treatment of bronchitis, sinusitis, community-acquired pneumonia, and skin infections (abscesses, wounds) caused by S. pneumoniae, H. influenzae, S. aureus, M. pneumoniae, C. pneumoniae, L. pneumophila, S. pyogenes
FDA Label

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Mechanism of Action
The bactericidal action of Gatifloxacin results from inhibition of the enzymes topoisomerase II (DNA gyrase) and topoisomerase IV, which are required for bacterial DNA replication, transcription, repair, and recombination.

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Pharmacodynamics
Gatifloxacin is a synthetic broad-spectrum 8-methoxyfluoroquinolone antibacterial agent for oral or intravenous administration. is bactericidal and its mode of action depends on blocking of bacterial DNA replication by binding itself to an enzyme called DNA gyrase, which allows the untwisting required to replicate one DNA double helix into two. Notably the drug has 100 times higher affinity for bacterial DNA gyrase than for mammalian. Gatifloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria. It should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.

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We determined the inhibitory activities of gatifloxacin against Staphylococcus aureus topoisomerase IV, Escherichia coli DNA gyrase, and HeLa cell topoisomerase II and compared them with those of several quinolones. The inhibitory activities of quinolones against these type II topoisomerases significantly correlated with their antibacterial activities or cytotoxicities (correlation coefficient [r] = 0.926 for S. aureus, r = 0.972 for E. coli, and r = 0.648 for HeLa cells). Gatifloxacin possessed potent inhibitory activities against bacterial type II topoisomerases (50% inhibitory concentration [IC50] = 13.8 microg/ml for S. aureus topoisomerase IV; IC50 = 0.109 microg/ml for E. coli DNA gyrase) but the lowest activity against HeLa cell topoisomerase II (IC50 = 265 microg/ml) among the quinolones tested. There was also a significant correlation between the inhibitory activities of quinolones against S. aureus topoisomerase IV and those against E. coli DNA gyrase (r = 0.969). However, the inhibitory activity against HeLa cell topoisomerase II did not correlate with that against either bacterial enzyme. The IC50 of gatifloxacin for HeLa cell topoisomerase II was 19 and was more than 2,400 times higher than that for S. aureus topoisomerase IV and that for E. coli DNA gyrase. These ratios were higher than those for other quinolones, indicating that gatifloxacin possesses a higher selectivity for bacterial type II topoisomerases. [1]

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Alternate mutations in the grlA and gyrA genes were observed through the first- to fourth-step mutants which were obtained from four Staphylococcus aureus strains by sequential selection with several fluoroquinolones. The increases in the MICs of gatifloxacin accompanying those mutational steps suggest that primary targets of gatifloxacin in the wild type and the first-, second-, and third-step mutants are wild-type topoisomerase IV (topo IV), wild-type DNA gyrase, singly mutated topo IV, and singly mutated DNA gyrase, respectively. Gatifloxacin had activity equal to that of tosufloxacin and activity more potent than those of norfloxacin, ofloxacin, ciprofloxacin, and sparfloxacin against the second-step mutants (grlA gyrA; gatifloxacin MIC range, 1.56 to 3.13 microg/ml) and had the most potent activity against the third-step mutants (grlA gyrA grlA; gatifloxacin MIC range, 1.56 to 6.25 microg/ml), suggesting that gatifloxacin possesses the most potent inhibitory activity against singly mutated topo IV and singly mutated DNA gyrase among the quinolones tested. Moreover, gatifloxacin selected resistant mutants from wild-type and the second-step mutants at a low frequency. Gatifloxacin possessed potent activity (MIC, 0.39 microg/ml) against the NorA-overproducing strain S. aureus NY12, the norA transformant, which was slightly lower than that against the parent strain SA113. The increases in the MICs of the quinolones tested against NY12 were negatively correlated with the hydrophobicity of the quinolones (correlation coefficient, -0.93; P < 0.01). Therefore, this slight decrease in the activity of gatifloxacin is attributable to its high hydrophobicity. Those properties of gatifloxacin likely explain its good activity against quinolone-resistant clinical isolates of S. aureus harboring the grlA, gyrA, and/or norA mutations. [2]

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Gatifloxacin can cause both hypoglycemia and hyperglycemia in both diabetic and non-diabetic patients. Gatifloxacin recently has been reported to stimulate insulin secretion by inhibition of ATP-sensitive K(+) (K(ATP)) channels in pancreatic beta-cells. Gatifloxacin-induced hypoglycemia is associated with concomitant use of sulfonylureas, and usually occurs immediately after administration of the drug. We find that gatifloxacin acutely stimulates insulin secretion from mouse pancreatic islets and that glibenclamide has additive effects on gatifloxacin-induced insulin secretion. On the other hand, gatifloxacin-induced hyperglycemia often takes several days to develop. We also demonstrate that chronic gatifloxacin treatment decreases islet insulin content by inhibiting insulin biosynthesis, which process may be associated with gatifloxacin-induced hyperglycemia. Moreover, discontinuation of gatifloxacin results in improved insulin secretory response. These data clarify the differing mechanisms of gatifloxacin-induced hyper- and hypoglycemia, and suggest that blood glucose levels should be carefully monitored during gatifloxacin administration, especially in elderly patients with renal insufficiency, unrecognized diabetes, or other metabolic disorders. Because the risk of potentially life-threatening dysglycemia is increased during gatifloxacin therapy, these findings have important implications for clinical practice. [3]

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In the present work, we evaluated the effect of gatifloxacin on the evolution of experimental murine infection with Nocardia brasiliensis using linezolid as a control. Gatifloxacin was injected subcutaneously at 100 mg/kg body weight every 8 h for 4 weeks. This compound was equally as efficient as linezolid in reducing the production of lesions. [4]

C19H23CLFN3O4

411.8550

411.136

121577-32-0

Gatifloxacin;112811-59-3;Gatifloxacin-d3 hydrochloride; Gatifloxacin sesquihydrate; 121577-32-0; 316819-28-0 (mesylate); 180200-66-2 (sesquihydrate); 404858-36-2 (hemihydrate); 1190043-25-4; 121577-32-0; 1189946-71-1

17956339

White to off-white solid powder

3

8

4

28

653

0

GQYBNVXJQVIRGC-UHFFFAOYSA-N

InChI=1S/C19H22FN3O4.ClH/c1-10-8-22(6-5-21-10)16-14(20)7-12-15(18(16)27-2)23(11-3-4-11)9-13(17(12)24)19(25)26;/h7,9-11,21H,3-6,8H2,1-2H3,(H,25,26);1H

1-cyclopropyl-6-fluoro-8-methoxy-7-(3-methylpiperazin-1-yl)-4-oxoquinoline-3-carboxylic acid;hydrochloride

gatifloxacin hydrochloride; 121577-32-0; Gatifloxacinacid; 160738-57-8; Gatifloxacin HCl; Gatifloxacin (hydrochloride); C3J4S9UD4E; Gatifloxacin hydrochloride [WHO-DD];

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O : ~10 mg/mL (~24.28 mM)
DMSO : ~4 mg/mL (~9.71 mM)

Solubility in Formulation 1: 6.67 mg/mL (16.19 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication (<60°C).

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 (Please use freshly prepared in vivo formulations for optimal results.)