Bacterial DNA gyrase; fluoroquinolone antibacterial

Lascufloxacin demonstrated antibacterial efficacy against beta-lactamase-negative ampicillin-susceptible and ampicillin-resistant strains of Haemophilus influenzae and Moraxella catarrhalis among Gram-negative bacteria, with MIC90 values of 0.06 μg/ml in every instance. milliliter. values for MIC90 of Acinetobacter spp., Klebsiella pneumoniae, and Enterobacter spp. The respective values are 0.25 μg/mL, 0.25 μg/mL, and 0.5 μg/mL. With MIC90 values of 0.25 μg/mL and 4 μg/mL, respectively, lascufloxacin inhibits Escherichia coli and Pseudomonas aeruginosa. Lascufloxacin has MIC50 and MIC90 values of 0.12 μg/mL and 0.25 μg/mL, respectively, against Mycoplasma pneumoniae. Lascufloxacin has a MIC90 of 0.12 μg/mL and exhibits strong action against isolates of Mycoplasma pneumoniae that are resistant to macrolides[1]. The minimum inhibitory concentration (MIC) of Lascufloxacin for the parent strain of Staphylococcus aureus varies from 0.008 to 0.015 μg/mL. In the fourth phase, the MIC for the mutant strains of parC, gyrA, parC, and gyrA is 2 μg/mL. To mutant strains, lascufloxacin exhibited partial cross-resistance. When it comes to first- and second-step mutant strains of Streptococcus pneumoniae, Lascufloxacin is more effective than other quinolones. Its minimum inhibitory concentration (MIC) against the gyrA and parC double mutant strains is 0.25 to 0.5 μg/mL [1].

Pharmacodynamic studies employing a mouse thigh infection model indicated that the ratio of the area under the free curve (fAUC) to MIC in plasma required for bacteriostasis or 1-log or 2-log CFU kills of S. pneumoniae isolates is 10, 16 and 28 correspondingly. Lascufloxacin displayed considerable bacterial kills in mouse models when simulating the area under the concentration-time curve (AUC) in plasma at a dose of 75 mg per day [qd] [2].

Lascufloxacin exhibited a broad spectrum of activity against various clinical isolates. Furthermore, lascufloxacin showed the most potent activity against Gram-positive bacteria among the quinolones tested and incomplete cross-resistance against existing quinolone-resistant strains. Enzymatic analysis indicated that lascufloxacin had potent inhibitory activity against both wild-type and mutated target enzymes. These results suggest that lascufloxacin may be useful in treating infections caused by various pathogens, including quinolone-resistant strains.[1]

The study had a prospective, open-label single-dose design to evaluate the plasma and intrapulmonary pharmacokinetics of lascufloxacin after oral administration to healthy adult male volunteers. Subjects were allocated into five groups (six per group) so that each underwent bronchoscopy only once at time points of 1, 2, 4, 6, or 24 h after administration of the study drug. All subjects were given a single oral dose of 75 mg of lascufloxacin tablets (Kyorin Pharmaceutical Co., Ltd., Tokyo, Japan), under fasting conditions. Healthy Japanese male subjects aged 20 to 40 years were recruited for this study; principal eligibility criteria included a body mass index of 18.5 to 24.9 kg/m2, no history of smoking, and no clinically significant abnormalities in vital signs, ECG, or clinical laboratory tests according to diagnosis during the screening period. Exclusion criteria included mainly a history of hypersensitivity to lidocaine, atropine, local anesthetics, or other medications, medical histories of food allergy or atopic disease, the presence of serious functional disorders or complications that would represent an obstacle to the investigation, a history of excessive alcohol or caffeine consumption, and a positive HIV or hepatitis B or C virus status. All subjects were provided written informed consent prior to enrollment in the study. The protocol was approved by the Institutional Review Board of the study site. The study was conducted at Osaka Pharmacology Clinical Research Hospital (Osaka, Japan) in accordance with the Declaration of Helsinki and the guidelines on Good Clinical Practice. This study was registered at JAPIC under registration number JapicCTI-142547.[2]

This study was performed to investigate the intrapulmonary penetration of lascufloxacin in humans. Thirty healthy adult male Japanese subjects, allocated into five groups, received lascufloxacin in a single oral dose of 75 mg. Bronchoalveolar lavage and blood sampling were performed simultaneously in each subject at 1, 2, 4, 6, or 24 h after administration, and lascufloxacin concentrations in plasma, epithelial lining fluid, and alveolar macrophages were determined. Lascufloxacin was rapidly distributed to the epithelial lining fluid with a time to maximum drug concentration (Tmax) of 1 h, which was identical to that in plasma. The maximum concentration of drug (Cmax) values in plasma, epithelial lining fluid, and alveolar macrophages were 0.576, 12.3, and 21.8 μg/ml, respectively. The corresponding area under the concentration-time curve from 0 to 24 h (AUC0-24) values were 7.67, 123, and 325 μg · h/ml. The mean drug concentrations in the epithelial lining fluid and alveolar macrophages were much higher than those in plasma at all time points examined, and the average site-to-free plasma concentration ratios fell within the ranges of 57.5 to 86.4 and 71.0 to 217, respectively. Drug levels in epithelial lining fluid and alveolar macrophages exceeded the MIC90 values for common respiratory pathogens. (This study was registered at JAPIC under registration number JapicCTI-142547.).[2]

Lascufloxacin was well tolerated by all subjects, without serious adverse events (AEs) and with no serious abnormal changes in vital signs or in the results of 12-lead electrocardiogram (ECG) or clinical laboratory tests. Of the 31 subjects enrolled in this study, 17 showed a total of 25 nonserious AEs. The most commonly reported AEs were increases in C-reactive protein in nine subjects, fever after the BAL procedure in six subjects, leukocytosis and headache in three subjects each, and feeling of body heat in two subjects. All of these AEs were considered to be related to the BAL procedure, and a causal relationship to the study drug was excluded.[2]

[1]. In Vitro Activities and Spectrum of the Novel Fluoroquinolone Lascufloxacin (KRP-AM1977). Antimicrob Agents Chemother. 2017 May 24;61(6). pii: e00120-17.

[2]. Intrapulmonary Pharmacokinetics of Lascufloxacin in Healthy Adult Volunteers. Antimicrob Agents Chemother. 2018 Mar 27;62(4). pii: e02169-17.

Lascufloxacin (AM-1977) is a novel 8-methoxy fluoroquinolone antibacterial agent with unique pharmacophores at the 1st and 7th positions of the quinoline nucleus. Its oral and parenteral formulations are being developed for the treatment of community-acquired pneumonia and other respiratory tract infections in Japan. Lascufloxacin has potent in vitro activity against various respiratory pathogens, such as Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and Mycoplasma pneumoniae. Data from microbiological studies suggested incomplete cross-resistance to lascufloxacin in strains resistant to existing quinolones and potent antibacterial activities against sequentially selected quinolone-resistant mutant Gram-positive bacteria.
A preclinical pharmacodynamic study using a mouse thigh infection model indicated that the ratios of the free area under the curve (fAUC) to MIC in plasma required for bacteriostasis, or 1-log or 2-log CFU killing against S. pneumoniae isolates, were 10, 16, and 28, respectively. Following single and repeated doses in phase I studies, it was suggested that lascufloxacin should achieve these pharmacodynamic targets at a dose of ≤100 mg per day, which is about 5 times lower than those of existing quinolones, such as levofloxacin. Murine pulmonary experimental results supported this dose setting: lascufloxacin showed significant bacterial killing in the mouse model when we emulated the area under the concentration-time curve (AUC) in plasma in the clinical dose (lascufloxacin, 75 mg per day [q.d.]); (levofloxacin, 500 mg q.d.).
Phase I studies of lascufloxacin exhibited favorable pharmacokinetic profiles with a complete gastrointestinal absorption, an adequate elimination half-life, 15.6 to 18.2 h, suitable for once-daily dosing, and an approximately dose-proportional increase in AUC as well as in maximum concentration in plasma (Cmax): total body clearance and volume of distribution were 8.07 liters/h and 188 liters after 100 mg oral administration; the respective values were 7.62 liters/h and 172 liters after a 100-mg intravenous administration, and human plasma protein binding was 74.0%. These pharmacokinetic profiles and antibacterial activities suggest that lascufloxacin has potential as an efficient treatment for respiratory infections.[2]

C21H25CLF3N3O4

475.8891

475.148

C, 53.00 H, 5.30 Cl, 7.45 F, 11.98N,8.83O, 13.45

1433857-09-0

848416-07-9;1433857-09-0 (HCl);

71528767

Typically exists as solid at room temperature

3

10

8

32

735

2

COC1=C2C(=CC(=C1N3C[C@@H]([C@@H](C3)F)CNC4CC4)F)C(=O)C(=CN2CCF)C(=O)O.Cl

YQHZQIJEMFMUGH-DFIJPDEKSA-N

InChI=1S/C21H24F3N3O4.ClH/c1-31-20-17-13(19(28)14(21(29)30)9-26(17)5-4-22)6-15(23)18(20)27-8-11(16(24)10-27)7-25-12-2-3-12/h6,9,11-12,16,25H,2-5,7-8,10H2,1H3,(H,29,30)1H/t11-,16+/m0./s1

7-[(3S,4S)-3-[(cyclopropylamino)methyl]-4-fluoropyrrolidin-1-yl]-6-fluoro-1-(2-fluoroethyl)-8-methoxy-4-oxoquinoline-3-carboxylic acid;hydrochloride

Lascufloxacin hydrochloride; Lascufloxacin HCl; Lascufloxacin; 848416-07-9; Lascufloxacin [INN]; KRP-AM1977; UNII-55MOB566V7; 7-((3S,4S)-3-((Cyclopropylamino)methyl)-4-fluoropyrrolidin-1-yl)-6-fluoro-1-(2-fluoroethyl)-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid; 55MOB566V7; LASCUFLOXACIN [WHO-DD]; KRP-AM1977; KRP-AM-1977; KRP-AM 1977; KRP-AM1977X; KRP-AM1977Y; Lascufloxacin

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

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

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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