Balofloxacin

Description

Balofloxacin, a novel orally-active fluoroquinolone antibiotic, was introduced in South Korea for the treatment of urinary tract infections (UTI). It can be synthetized by reaction of 3-(methylamino)piperidine with the classical 4-quinolone-3-carboxylic acid template. In vitro antibacterial activity of balofloxacin against gram-positive bacteria (Staphylococcus aureus including methicillin-resistant S. aureus, Staphylococcus epidermis, Streptococcus pneumonia, Streptococcus pyrogenes) was almost equal to that of sparfloxacin or tosufloxacin, in contrast its activity against gram-negative bacteria was 2 times or more lower. In clinical trials, balofloxacin was well tolerated and showed comparable efficacy to ofloxacin in patients with UTls. After oral administration, balofloxacin was well absorbed, and was primarily eliminated unchanged in the urine with an elimination half-life of approximately 8 h. In animal studies, balofloxacin did not exhibit any phototoxicity.

Chemical properties

Crystalline Solid

Originator

Chugai Pharmaceutical (Japan)

The Uses of Balofloxacin

Balofloxacin is quinolone antibiotic, inhibiting the synthesis of bacterial DNA by interference with the enqyme DNA gyrase.

The Uses of Balofloxacin

Fluorinated quinolone antibacterial.

Manufacturing Process

(1) A mixture of ethyl 1-cyclopropyl-6,7,8-trifluoro-1,4-dihydro-4- oxoquinoline-3-carboxylate (933 mg), 3-acetamidopiperidine (710 mg), triethylamine (400 mg) and dimethylsulfoxide (10 ml) was heated at 100°C for 2 hours with stirring. Thereafter the mixture was cooled down and ice water was added thereto. The resulting mixture was extracted with chloroform and the chloroform layer was washed with water three times before being dried over anhydrous sodium sulfate. Removal of the solvent in vacuum followed by purification by silica gel column chromatography (chloroformethanol) gave ethyl 7-(3-acetamidopiperidin-1-yl)-1-cyclopropyl-6,8-difluoro- 1,4-dihydro-4-oxo quinoline-3-carboxylate (930 mg). Re-crystallization from ethanol-ether afforded a colorless crystalline substance (MP: 217°-218°C).
(2) Ethyl 7-(3-acetamidopiperidin-1-yl)-1-cyclopropyl-6,8-difluoro-1,4-dihydro- 4-oxo-quinoline-3-carboxylate obtained from the foregoing step: (a) (433 mg) of above product was dissolved in 6 N hydrochloric acid (5 ml) and heated at 100°C. for 2.5 hours with stirring. After the removal of the solvent in vacuum, methanol was added to the residue and the insoluble materials were filtered off. Removal of the solvent followed by purification by silica gel column chromatography (chloroform-methanol) gave hydrochloride of 7-(3-aminopiperidin-1-yl)-1-cyclopropyl-6,8-difluoro-1,4-dihydro-4- oxoquinoline-3-carboxylic acid (colorless, crystalline-powder). MP: color change at about 272°C, decomposition at about 280°C.
(b) A mixture of 7-(3-acetamidopiperidin-1-yl)-1-cyclopropyl-6,8-difluoro-1,4- dihydro-4-oxoquinoline-3-carboxylic acid (4.05 g), sodium methoxide (2.16 g) and N,N-dimethylformamide (120 ml) was stirred for 2 hours at 100°-140°C. The reaction mixture was concentrated in vacuum and water was added to the residue. The mixture was neutralized with 1 N hydrochloric acid and the neutralized mixture was then concentrated in vacuum. Purification of the concentrated mixture by silica gel column chromatography (chloroformmethanol) gave 7-(3-acetamidopiperidin-1-yl)-1-cyclopropyl-6-fluoro-1,4- dihydro-8-methoxy-4-oxoquinoline-3-carboxylic acid. MP: 248°-250°C.
(c) 7-(3-Acetamidopiperidin-1-yl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8- methoxy-4-oxoquinoline-3-carboxylic acid (1.25 g) above obtained was suspended in 6 N hydrochloric acid (30 ml) and ethanol (5 ml) and heated at 100°C for 3 hours. Then the reaction mixture was concentrated in vacuum and the residue was purified by silica gel column chromatography (chloroform:methanol:ammonium hydroxide=100:30:5) to afford 7-(3- aminopiperidin-1-yl)-1-cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-4- oxoquinoline-3-carboxylic acid. MP: 176°-177°C.

brand name

Q-Roxin

Therapeutic Function

Antibacterial

Pharmaceutical Applications

A 6-fluoro-8-methoxy quinolone derivative. It has good antistaphylococcal activity (MIC 0.4–4 mg/L), but is inactive against methicillin-resistant Staph. aureus (MRSA) and quinolone-resistant Staph. aureus; Str. pneumoniae is inhibited by 0.4 mg/L. It has good activity against Enterobacteriaceae, but is inactive against Ps. aeruginosa (MIC 8–16 mg/L). After a 200 mg oral dose a peak level of 1.7 mg/L is reached in 1 h. The apparent elimination halflife is about 8 h, rising to 13 h in elderly subjects. Plasma protein binding is about 16%. It was withdrawn from the market in Japan because of adverse events, but is available in China.