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
After oral administration, gatifloxacin is well absorbed in the gastrointestinal tract, with an absolute bioavailability of 96%. Metabolisms/Metabolites Gatifloxacin undergoes limited biotransformation in the human body; less than 1% of the dose is excreted in the urine as ethylenediamine and methylethylenediamine metabolites. Half-life: 7-14 hours

Toxicity Summary
Gatifloxacin's bactericidal effect stems from its inhibition of topoisomerase II (DNA gyrase) and topoisomerase IV, both essential enzymes for bacterial DNA replication, transcription, repair, and recombination. Pregnancy and Lactation Effects ◉ Overview of Use During Lactation There is currently no clinical information regarding the use of gatifloxacin during lactation. Traditionally, fluoroquinolones are not used in infants due to concerns about adverse effects on developing joints. However, recent studies suggest the risk is minimal. Calcium in breast milk may prevent the absorption of small amounts of fluoroquinolones in breast milk, but there is currently insufficient data to confirm or refute this claim. Lactating women may use gatifloxacin, but monitoring for potential impacts on the infant's gut microbiota, such as diarrhea or candidiasis (thrush, diaper rash), is necessary. However, it is generally preferable to use other medications with known safety information. The risk to a breastfeeding infant from the mother's use of gatifloxacin-containing ear drops or eye drops is negligible. After using eye drops, to significantly reduce the amount of medication entering breast milk, press the tear duct at the corner of the eye for at least 1 minute, then blot away any excess medication with absorbent tissue.
◉ Effects on breastfed infants
No published information found as of the revision date.
◉ Effects on lactation and breast milk
No published information found as of the revision date.

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Protein binding rate
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, chemically named 4-oxo-1,4-dihydroquinoline-3-carboxylic acid, with a cyclopropyl group substituted at the nitrogen atom, and fluorine, 3-methylpiperazin-1-yl, and methoxy groups substituted at positions 6, 7, and 8, respectively. Gatifloxacin belongs to the fourth-generation fluoroquinolone antibiotic class and, like other drugs in its class, inhibits bacterial topoisomerase type II. It has a dual action of anti-infection, inhibition of DNA topoisomerase (ATP hydrolase), and antibacterial activity. Gatifloxacin is a quinoline monocarboxylic acid, N-arylpiperazine, organofluorine compound, quinolone compound, and quinolone antibiotic. It works by inhibiting bacterial DNA gyrase and topoisomerase IV. In 1999, Bristol-Myers Squibb first launched gatifloxacin under the brand name Tequin® for the treatment of respiratory infections. Gatifloxacin is available in tablets and various aqueous solutions for intravenous injection. In addition, it is also available as an eye drop formulation under the brand name Zymar®, marketed by Allergan. Due to the high incidence of reported adverse events related to glycemic abnormalities associated with gatifloxacin, and the higher probability of hyperglycemia and hypoglycemia in patients taking gatifloxacin compared to those taking macrolide antibiotics, the FDA withdrew approval for non-ophthalmic drug products containing gatifloxacin. Anhydrous gatifloxacin is a quinolone antibacterial drug. Gatifloxacin is a synthetic 8-methoxyfluoroquinolone compound with antibacterial activity against a variety of Gram-negative and Gram-positive bacteria. Gatifloxacin works by inhibiting DNA gyrase (an enzyme involved in DNA replication, transcription, and repair) and topoisomerase IV (an enzyme involved in the allocation of chromosomal DNA during bacterial cell division). Gatifloxacin is a fourth-generation fluoroquinolone antibiotic that, like other drugs in its class, inhibits bacterial DNA gyrase and topoisomerase IV. Bristol-Myers Squibb launched gatifloxacin in 1999 under the brand name Tequin® for the treatment of respiratory infections. The company licensed the drug from Kyorin Pharmaceutical Co., Ltd. of Japan. Allergan produces an eye drop formulation called Zymar®. Gatifloxacin is available in tablets and various aqueous solutions for intravenous injection. [Wikipedia]
A fluoroquinolone antibacterial agent and DNA topoisomerase II inhibitor, used as an ophthalmic solution for the treatment of bacterial conjunctivitis.

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Drug Indications
For the treatment of bronchitis, sinusitis, community-acquired pneumonia, and skin infections (abscesses, wounds) caused by Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila, and Streptococcus pyogenes.
FDA Label
Mechanism of Action
Gatifloxacin's bactericidal action stems from its inhibition of topoisomerase II (DNA gyrase) and topoisomerase IV, two enzymes essential for bacterial DNA replication, transcription, repair, and degradation.
Pharmacodynamics
Gatifloxacin is a synthetic broad-spectrum 8-methoxyfluoroquinolone antibacterial drug, available orally or intravenously. It has bactericidal activity by binding to an enzyme called DNA gyrase, blocking bacterial DNA replication. DNA gyrase unwinds the DNA double helix, thus preventing DNA replication into two double helices. Notably, this drug has an affinity for bacterial DNA gyrase that is 100 times greater than that for mammalian DNA gyrase. Gatifloxacin is a broad-spectrum antibiotic effective against both Gram-positive and Gram-negative bacteria. This product is intended only for the treatment or prophylaxis of infections confirmed or highly suspected to be caused by bacteria. 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 the inhibitory activities of several quinolone drugs. The inhibitory activities of quinolones against these type II topoisomerases were significantly correlated with their antibacterial activity or cytotoxicity (correlation coefficients [r] = 0.926 for Staphylococcus aureus, r = 0.972 for Escherichia coli, and r = 0.648 for HeLa cells). Gatifloxacin exhibited potent inhibitory activity against bacterial type II topoisomerases (IC50 for Staphylococcus aureus topoisomerase IV was 13.8 μg/ml; IC50 for Escherichia coli DNA gyrase was 0.109 μg/ml), but among the quinolones tested, it showed the lowest activity against HeLa cell topoisomerase II (IC50 265 μg/ml). There was a significant correlation between the inhibitory activities of quinolone drugs on Staphylococcus aureus topoisomerase IV and Escherichia coli DNA gyrase (r = 0.969). However, their inhibitory activity on HeLa cell topoisomerase II was not correlated with their inhibitory activity on either of these two bacterial enzymes. Gatifloxacin had an IC50 value of 19 against HeLa cell topoisomerase II, which was more than 2400 times higher than its IC50 values against Staphylococcus aureus topoisomerase IV and Escherichia coli DNA gyrase. These ratios are higher than those of other quinolone drugs, indicating that gatifloxacin has higher selectivity for bacterial type II topoisomerases. [1]

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Through sequential screening of four Staphylococcus aureus strains with multiple fluoroquinolone drugs, mutants of the first to fourth steps were obtained, and alternating mutations in the grlA and gyrA genes were observed. The increase in gatifloxacin MIC accompanying these mutation steps indicates that the main targets of gatifloxacin in wild-type and the first, second, and third step mutants are wild-type topoisomerase IV, wild-type DNA gyrase, single mutant topoisomerase IV, and single mutant DNA gyrase, respectively. Gatifloxacin's activity against the second step mutant (grlA gyrA; gatifloxacin MIC range 1.56 to 3.13 μg/ml) is comparable to tosufloxacin and superior to norfloxacin, ofloxacin, ciprofloxacin, and sparfloxacin; its activity against the third step mutant (grlA gyrA grlA; gatifloxacin MIC range 1.56 to 6.25 μg/ml) is the strongest, indicating that among the quinolones tested, gatifloxacin has the strongest inhibitory activity against single mutant topoisomerase IV and single mutant DNA gyrase. In addition, gatifloxacin screened out resistant mutants from wild-type and step-2 mutants at a low frequency. Gatifloxacin had potent antimicrobial activity against Staphylococcus aureus strain NY12 overexpressing NorA (norA transformant) (MIC 0.39 μg/ml), but slightly lower than its antimicrobial activity against the parental strain SA113. The increase in MIC value of quinolone drugs tested against NY12 strain was negatively correlated with the hydrophobicity of quinolone drugs (correlation coefficient -0.93; P < 0.01). Therefore, the slight decrease in the antimicrobial activity of gatifloxacin can be attributed to its high hydrophobicity. These properties of gatifloxacin may explain its good antimicrobial activity against clinical isolates of quinolone-resistant Staphylococcus aureus carrying grlA, gyrA and/or norA mutations. [2]

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Gatifloxacin can cause hypoglycemia and hyperglycemia in diabetic and non-diabetic patients. Recent reports indicate that gatifloxacin stimulates insulin secretion by inhibiting ATP-sensitive potassium channels (K(ATP) channels) in pancreatic β-cells. Gatifloxacin-induced hypoglycemia is associated with co-administration of sulfonylureas and typically occurs immediately after administration. We found that gatifloxacin acutely stimulates insulin secretion in mouse islets, while glibenclamide has an additive effect on gatifloxacin-induced insulin secretion. On the other hand, gatifloxacin-induced hyperglycemia usually takes several days to develop. We also demonstrated that long-term use of gatifloxacin reduces islet insulin levels by inhibiting insulin biosynthesis, a process that may be related to gatifloxacin-induced hyperglycemia. Furthermore, discontinuation of gatifloxacin improves insulin secretion response. These data elucidate the different mechanisms by which gatifloxacin induces hyperglycemia and hypoglycemia and suggest close monitoring of blood glucose levels during gatifloxacin administration, especially in elderly patients with renal insufficiency, undiagnosed diabetes, or other metabolic disorders. These findings have significant implications for clinical practice due to the increased risk of potentially life-threatening glycemic abnormalities during gatifloxacin treatment. [3] In this study, we evaluated the effect of gatifloxacin on the progression of Nocardia brasiliensis infection in experimental mice, using linezolid as a control. Gatifloxacin was administered subcutaneously at a dose of 100 mg/kg body weight every 8 hours for 4 weeks. This compound was as effective as linezolid in reducing lesion formation. [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.)