Quinolones

Development of synthetic quinolone antibacterial agents has experienced three generations. The typical representative of the first generation quinolone is the nalidixic acid developed in 1962. It is effective in the treatment of Gram-negative bacteria such as Escherichia coli but not effective in the treatment in Pseudomonas aeruginosa and gram-positive bacteria with poor absorption capability and low biological availability. It is easy to cause bacteria drug resistance and thus had been eliminated. Typical representative of the secondary generation of quinolones include oxolinic acid and pipemidic acid developed in 1970s. In 1979, our country had applied pipemidic acid to the treatment of infections caused by Gram-negative bacteria and had achieved excellent efficacy. It therapeutic efficacy on Pseudomonas aeruginosa infection is superior to nalidixic acid and carbenicillin, but not as good as gentamicin. The disadvantage is that it has a poor efficacy in the treatment of gram-positive bacteria with low blood levels as well as certain central nervous system toxicity.

In the late 1970s, the development of cephalosporins had reached its peak. However, the price is so high that general patient can hardly afford it. The development of the third generation quinolone-synthetic fluoroquinolone antibiotic had given the world the feeling of “mountains multiply and streams double back no doubt, there is a way out". Fluoroquinolone antibiotic refers to the novel type of quinolone antibacterial drugs with the six position of the synthetic quinazoline ring being introduced into a fluorine atom. They not only have a 4-64 fold stronger efficacy against gram-negative bacteria than the first and second generation quinolones, but also have an 8 to 64 fold stronger effect than the first and second generation quinolones in the treatment of gram-positive bacteria. Moreover, they have excellent oral absorption property and rarely cause drug resistance. Furthermore, as a kind of synthetic chemicals, it is relatively more inexpensive than general antibiotics (especially third generation cephalosporins).

The DNA of bacterial cells exists in the form of double-stranded helix with the formation of double helix relying on the action of DNA gyrase. The mechanism of action of quinolones is through the inhibition of DNA gyrase, causing chromosome damage, resulting in the failure of the division and reproduction of the cells. Because of its unique mechanism of action, which is free of the impact from the plasmid conducting drug resistance, it has no cross-resistance with many kinds of antibacterial drugs.

The advantage of fluoroquinolone antibiotics are as follows:
1. It has broad antimicrobial spectrum and strong antibacterial activity with some of them (such as ofloxacin) having their effects comparable with third-generation cephalosporins. It also has effect against Gram-positive bacteria Staphylococcus aureus and refractory methicillin-resistant Staphylococcus aureus (MRSA); in terms of its antibacterial effect against gram-negative bacteria, it has spread to Pseudomonas aeruginosa, Haemophilus influenzae, and penicillin enzyme-producing Neisseria gonorrhoeae; some kinds of novel fluoroquinolone antibiotics are even effective in the treatment of mycoplasma and chlamydia.
2. It has excellent oral absorption property with wide tissue distribution. Usually fluoro quinolone administrated orally need 1 to 2 hours to reach the concentration peak in blood. It has a low plasma protein binding rate at about 10% to 40%. After the drug administration, it can be widely distributed in liver, kidney, skin and lungs and other tissues.
3. It has wide range of treatment with certain therapeutic effect on intestinal, urinary tract, biliary tract, respiratory tract infections, prostatitis, osteomyelitis, etc. It is widely used in the treatment of infections of various subjects.
4. Low incidence of drug resistance. Ofloxacin, used in Germany, can still inhibit over 96.8% of Gram-negative bacteria and 93.3% of gram-positive bacteria after eight years; ciprofloxacin used in the UK has 91% of Pseudomonas aeruginosa and 95% of Staphylococcus be sensitive to it; However, there is research in our country indicated that the resistance against fluoroquinolone for Pseudomonas aeruginosa has risen in recent years, from 4.4% to 10%.

Characteristics of fluoroquinolone antibiotics are as follows.
1. Its antibacterial effect, in general, is poorer against gram-positive bacteria than gram-negative bacteria.
2. The related adverse effects include gastrointestinal symptoms, usually doesn’t need stopping; for central nervous system symptoms, such as anxiety, nervousness, insomnia and headaches are more common for ciprofloxacin; rash may also occur; the incidence of liver and kidney dysfunction is generally 0.5% to 1.0%.
3. Long-term puppy magnetic resonance imaging (MRI) and ultrasound studies have shown that there is loose phenomenon occurring on the intermediate layer of bone and joint cartilage matrix. However, this phenomenon hasn’t been observed in hundreds of cases of human. Still for safety purpose, this class of drugs is not recommended to be long-term administrated to lactating woman and children upon bone development in large dose. Because this product inhibit the replication of DNA, so pregnant women should also administrate it with caution.
4. Individual kinds of fluoroquinolones (such as lomefloxacin, enoxacin and sparfloxacin), when being subject to long-term administration to elderly outdoor-working farmers in large dose, can cause phototoxic reactions in a few cases.

There are several conditions where drug interactions can happen:
1. administration together with milk, cheese and calcium, magnesium, iron, aluminum and other drugs will affect the antibacterial effect; it is generally recommended to be administrated upon an empty stomach; if administrated after meals, the peak time of drug in the blood will be postponed for 1 to 2 hours, but the total amount of the absorption will not be affected; acidic urine can further facilitate its excretion while precipitation can happen in alkaline urine.
2. Interaction with theophylline and other xanthine drugs can be divided into three categories: when administrated together with enoxacin, the plasma concentration of theophylline can be increased by two fold; administration together with tosufloxacin and ciprofloxain can cause 20% increase of the blood concentration of theophylline; administration together with lomefloxacin and norfloxacin has no effect on plasma concentrations of theophylline.
3. Administration together with non-steroidal anti-inflammatory drugs fenbufen can promote the binding between fenbufen and γ- aminobutyric acid (GABA) receptors to induce epileptic seizures, so patients with a history of epilepsy should administrate with caution.
4. Administration together with other antimicrobial agents should also be cautious. For example, combination with vancomycin can cause increase in renal toxicity; combination with doxorubicin, furadantin can cause decreased kidney function (ciprofloxacin); combination with chloramphenicol, doxycycline, clindamycin and macrolide antibiotic can even cause decrease of its antibacterial effect, and can also prone to lead to adverse reactions of hematopoietic system and the nervous system.

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Structure Chemical Name CAS MF
Moxifloxacin Moxifloxacin 151096-09-2 C21H24FN3O4
Balofloxacin Balofloxacin 127294-70-6 C20H24FN3O4
Sarafloxacin hydrochloride Sarafloxacin hydrochloride 91296-87-6 C20H18ClF2N3O3
Norfloxacin Norfloxacin 70458-96-7 C16H18FN3O3
1-Cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-(3-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid 1-Cyclopropyl-6-fluoro-1,4-dihydro-8-methoxy-7-(3-methyl-1-piperazinyl)-4-oxo-3-quinolinecarboxylic acid 112811-59-3 C19H22FN3O4
Pazufloxacin Pazufloxacin 127045-41-4 C16H15FN2O4
Moxifloxacin hydrochloride Moxifloxacin hydrochloride 186826-86-8 C21H25ClFN3O4
Nadifloxacin Nadifloxacin 124858-35-1 C19H21FN2O4
Gemifioxacin Gemifioxacin 175463-14-6 C18H20FN5O4
Difloxacin Difloxacin 98106-17-3 C21H19F2N3O3
Prulifloxacin Prulifloxacin 123447-62-1 C21H20FN3O6S
Enrofloxacin hydrochloride Enrofloxacin hydrochloride 112732-17-9 C19H22FN3O3
Gatifloxacin sesquihydrate Gatifloxacin sesquihydrate 180200-66-2 C19H22FN3O4
Marbofloxacin Marbofloxacin 115550-35-1 C17H19FN4O4
Pazufloxacin mesilate Pazufloxacin mesilate 163680-77-1 C17H19FN2O7S
Sarafloxacin Sarafloxacin 98105-99-8 C20H17F2N3O3
1-ETHYL-6-FLUORO-7-(4-METHYLPIPERAZIN-1-YL)-4-OXO-QUINOLINE-3-CARBOXYLIC ACID 1-ETHYL-6-FLUORO-7-(4-METHYLPIPERAZIN-1-YL)-4-OXO-QUINOLINE-3-CARBOXYLIC ACID 149676-40-4 C18H28FN3O8S
Levofloxacin carboxylic acid Levofloxacin carboxylic acid 100986-89-8 C13H9F2NO4
SITAFLOXACIN SITAFLOXACIN 163253-35-8 C19H18ClF2N3O3.H2O
Tosufloxacin tosylate Tosufloxacin tosylate 115964-29-9 C26H23F3N4O6S
Nalidixic acid Nalidixic acid 389-08-2 C12H12N2O3
Fleroxacin Fleroxacin 79660-72-3 C17H18F3N3O3
TROVAFLOXACIN TROVAFLOXACIN 147059-72-1 C20H15F3N4O3
Enoxacin Enoxacin 74011-58-8 C15H17FN4O3
Orbifloxacin Orbifloxacin 113617-63-3 C19H20F3N3O3
CINOXACIN CINOXACIN 28657-80-9 C12H10N2O5
Levofloxacin hydrochloride Levofloxacin hydrochloride 100986-85-4 C18H20FN3O4
TEMAFLOXACIN TEMAFLOXACIN 108319-06-8 C21H18F3N3O3
Sparfloxacin Sparfloxacin 111542-93-9 C19H22F2N4O3
Grepafloxacin Grepafloxacin 119914-60-2 C19H22FN3O3
TOSUFLOXACIN TOSILATE TOSUFLOXACIN TOSILATE 100490-36-6 C26H23F3N4O6S
DANOFLOXACIN DANOFLOXACIN 112398-08-0 C19H20FN3O3
Gemifioxacin mesylate Gemifioxacin mesylate 210353-53-0 C19H24FN5O7S
Lomefloxacin hydrochloride Lomefloxacin hydrochloride 98079-52-8 C17H20ClF2N3O3
Clinafloxacin Clinafloxacin 105956-97-6 C17H17ClFN3O3
Besifloxacin hydrochloride Besifloxacin hydrochloride 405165-61-9 C19H21ClFN3O3.ClH
Enoxacin Enoxacin 84294-96-2 C30H40F2N8O9
Ofloxacin Ofloxacin 82419-36-1 C18H20FN3O4
Rimantadine Rimantadine 13392-28-4 C11H19N
Ciprofloxacin lactate Ciprofloxacin lactate 97867-33-9 C20H22FN3O5
Ciprofloxacin Ciprofloxacin 85721-33-1 C17H18FN3O3
Sparfloxacin Sparfloxacin 110871-86-8 C19H22F2N4O3
Olamufloxacin Olamufloxacin 167887-97-0 C20H23FN4O3
Tosufloxacin tosilate Tosufloxacin tosilate 107097-79-0 C26H23F3N4O6S
Difluoxacin hydrochloride Difluoxacin hydrochloride 91296-86-5 C21H20ClF2N3O3
Sitafloxacin Sitafloxacin 127254-12-0 C19H18ClF2N3O3
Gatifloxacin hydrochloride Gatifloxacin hydrochloride 160738-57-8 C22H28FN3O7
(R)-7-(3-Aminohexahydro-1H-azepin-1-yl)-8-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid (R)-7-(3-Aminohexahydro-1H-azepin-1-yl)-8-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid 141388-76-3 C19H21ClFN3O3
PRULIFLOXACIN PRULIFLOXACIN 123447-63-2 C21H20FN3O6S
Danofloxacin mesylate Danofloxacin mesylate 119478-55-6 C20H24FN3O6S
ENOXACIN GLUCONATE ENOXACIN GLUCONATE 104142-71-4 C15H17FN4O3.C6H12O7.H2O
OFLOXACIN HYDROCHLORIDE OFLOXACIN HYDROCHLORIDE C18H21ClFN3O4
FORMYLCIPROFLOXACIN FORMYLCIPROFLOXACIN 93594-39-9 C18H18FN3O4
Levofloxacin mesylate Levofloxacin mesylate 226578-51-4 C19H24FN3O7S
Norfloxacinehydrochloride Norfloxacinehydrochloride 68077-27-0 C16H19ClFN3O3
Garenoxacin Garenoxacin 194804-75-6 C23H20F2N2O4
1-Cyclopropyl-6-fluoro-1,4-dihydro-8-hydroxy-7-[(4aS,7aS)-octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl]-4-oxo-3-quinolinecarboxylic acid 1-Cyclopropyl-6-fluoro-1,4-dihydro-8-hydroxy-7-[(4aS,7aS)-octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl]-4-oxo-3-quinolinecarboxylic acid 721970-36-1 C20H22FN3O4
LEVOFLOXACIN ACID ESTER LEVOFLOXACIN ACID ESTER C15H13F2NO4
LEVOFLOXACIN ACID LEVOFLOXACIN ACID C13H9F2NO4
Desmethyl Levofloxacin Desmethyl Levofloxacin 117707-40-1 C17H18FN3O4
Levofloxacin heMihydrate Levofloxacin heMihydrate 138199-71-0 C18H21ClFN3O4
RUFLOXACIN RUFLOXACIN 101363-10-4 C17H18FN3O3S
Ciprofloxacin hydrochloride Ciprofloxacin hydrochloride 86483-48-9 C17H19ClFN3O3
Ofloxacin hydrochloride Ofloxacin hydrochloride 118120-51-7 C18H20FN3O4.HCl
Finafloxacin Hydrochloride Finafloxacin Hydrochloride 209342-41-6 C20H20ClFN4O4
Pefloxacin Pefloxacin 70458-92-3 C17H20FN3O3
Lomefloxacin Lomefloxacin 98079-51-7 C17H19F2N3O3
Grepafloxacin hydrochloride Grepafloxacin hydrochloride 161967-81-3 C19H23ClFN3O3
Miloxacin Miloxacin 37065-29-5 C12H9NO6
3-Quinolinecarboxylic acid, 1-cyclopropyl-6,8-difluoro-1,4-dihydro-7-(octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl)-4-oxo-, (4aS-cis)- 3-Quinolinecarboxylic acid, 1-cyclopropyl-6,8-difluoro-1,4-dihydro-7-(octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl)-4-oxo-, (4aS-cis)- 151213-15-9 C20H21F2N3O3
Clinafloxacin hydrochloride Clinafloxacin hydrochloride 105956-99-8 C17H18Cl2FN3O3
1-Cyclopropyl-8-ethoxy-6-fluoro-7-[(4aS,7aS)-octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl]-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 1-Cyclopropyl-8-ethoxy-6-fluoro-7-[(4aS,7aS)-octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl]-4-oxo-1,4-dihydroquinoline-3-carboxylic acid 1029364-75-7 C22H26FN3O4
ENROFLOXACIN LACTATE ENROFLOXACIN LACTATE 931066-01-2
Pipemidic acid Pipemidic acid 51940-44-4 C14H17N5O3
CIPROFLOXACIN LACTATE CIPROFLOXACIN LACTATE 857213-31-1 C20H24FN3O6
Enrofloxacin Sodium Enrofloxacin Sodium 266346-15-0 C19H21FN3O3.Na
Pefloxacin mesylate Pefloxacin mesylate 70458-95-6 C17H20FN3O3
MOXIFLOXACIN, HYDROCHLORIDE MONOHYDRATE MOXIFLOXACIN, HYDROCHLORIDE MONOHYDRATE 192927-63-2 C21H27ClFN3O5
OXOCIPROFLOXACIN OXOCIPROFLOXACIN C17H16FN3O4
(S)-(-)-Nadifloxacin (S)-(-)-Nadifloxacin 154357-42-3 C19H21FN2O4
Ciprofloxacin IMpurity A Ciprofloxacin IMpurity A C17H18FN3O3
OFLOXACIN RELATED COMPOUND A (25 MG) ((RS)-9-FLUORO-2,3-DIHYDRO-3-METHYL-7-OXO-10-(PIPERA-ZIN-1 -YL)-7H-PYRIDO[1,2,3-DE]-1,4-BENZOXAZINE-6-CARBOXYLIC ACID) OFLOXACIN RELATED COMPOUND A (25 MG) ((RS)-9-FLUORO-2,3-DIHYDRO-3-METHYL-7-OXO-10-(PIPERA-ZIN-1 -YL)-7H-PYRIDO[1,2,3-DE]-1,4-BENZOXAZINE-6-CARBOXYLIC ACID) 82419-52-1 C17H19ClFN3O4
rosoxacin        rosoxacin 40034-42-2 C17H14N2O3
amifloxacin     amifloxacin 86393-37-5 C16H19FN4O3
Pazufloxacin hydrochloride Pazufloxacin hydrochloride 127046-45-1 C16H15FN2O4.HCl
Gatifloxacin mesylate Gatifloxacin mesylate
1,2,2,2-tetrafluoroethane 1,2,2,2-tetrafluoroethane 29759-38-4 C16H18FN3O3C6H5NO3
SparfloxacinLactate SparfloxacinLactate C19H22F2N4O3┬ĚC3H6O3
FLEROXACINLACTATE FLEROXACINLACTATE 896139-71-2 C17H18F3N3O3.C3H6O3
Rufloxacin hydrochloride Rufloxacin hydrochloride 106017-08-7 C17H19ClFN3O3S
levofloxacin/ofloxacin levofloxacin/ofloxacin
Ciprofloxacin IMpurity E Ciprofloxacin IMpurity E C17H18FN3O3
GATIFLOXACIN MESYLATE GATIFLOXACIN MESYLATE 316819-28-0 C19H22FN3O4.CH4O3S
Lomefoxacin aspartate Lomefoxacin aspartate
Cadrofloxacin Cadrofloxacin 153808-85-6 C19H20F3N3O4
Ciprofloxacin Formamide Ciprofloxacin Formamide
Enrofloxacin nicotinate Enrofloxacin nicotinate
3-Quinolinecarboxylic acid, 1-cyclopropyl-8-ethoxy-6-fluoro-1,4-dihydro-7-(3-Methyl-1-piperazinyl)-4-oxo- 3-Quinolinecarboxylic acid, 1-cyclopropyl-8-ethoxy-6-fluoro-1,4-dihydro-7-(3-Methyl-1-piperazinyl)-4-oxo- 182868-72-0 C20H24FN3O4
CIPROFLOXACIN IMPURITY A CIPROFLOXACIN IMPURITY A C17H18FN3O3
Levofloxacin lactic acid Levofloxacin lactic acid C21H24FN3O6
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