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Dr. Koppala R.V.S. Chaitanya, profile picture
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Quinolones and fluoroquinolones

Quinolones were first developed in the 1960s and can be classified into generations based on their antimicrobial activity. First generation quinolones were active against gram-negative bacteria but not Pseudomonas. Later generations showed increased activity against gram-positive pathogens and mycobacteria. Quinolones act by inhibiting bacterial DNA gyrase and topoisomerase IV, blocking DNA synthesis. They are potent against a variety of bacteria including E. coli, Salmonella, and Staphylococcus. However, resistance may develop via mutations in genes encoding DNA gyrase/topoisomerase IV or active drug transport.

Health & Medicine◦
 Quinolones were first developed in the 1960s and can be classified into generations based on antimicrobial activity.  First Nalidixic acid in 1962.
Quinolones
 First Generation Gram-negative, but Pseudomonas spp.  Second Generation Gram-negative, some gram- positive and mycobacteria.  Third and Fourth Generation Have increased activity against gram-positive pathogens including S. pneumoniae. They are also active against many agents causing zoonotic infection and against mycobacteria.
 First Generation  Cinoxacin  Nalidixic Acid  Oxolinic acid  Second Generation  Ciprofloxacin  Enoxacin  Fleroxacin  Lomefloxacin  Levofloxacin  Norfloxacin  Ofloxacin  rulfloxacin  Third Generation  Gatifloxacin  Grepafloxacin  Pazufloxacin  Sparfloxacin  Tosufloxacin  Fourth Generation  Clinafloxacin  Gemifloxacin  Moxifloxacin  Trovafloxacin
Quinolones
The fluoroquinolones act by inhibiting type 2 bacterial DNA topoisomerases, DNA gyrase and topoisomerase IV. They bind to and trap the enzyme-DNA complex. This blocks DNA synthesis and cell growth and ultimately has a lethal effect on the cell.
Quinolones
The fluoroquinolones are potent bactericidal agents against:  E. coli and various species of Salmonella, Shigella, Enterobacter, Campylobacter, and Neisseria  Ciprofloxacin is more active than norfioxacin against P. aeruginosa  Fluoroquinolones also have good activity against staphylococci, including methicillin­resistant strains  Several intracellular bacteria are inhibited by fluoroquinolones these include species of Chlamydia, Mycoplasma, Legionella, Brucella, and Mycobacterium (including Mycobacterium tuberculosis)
Quinolones
 Resistance to quinolones may develop during therapy via mutations in the bacterial chromosomal genes encoding DNA gyrase or topoisomerase IV, or by active transport of the drug out of the bacteria.
Quinolones
Agent Administration Absorption Half-Life (hrs) Disposition Norfloxacin Oral 50% 4 (8 in anuria) M (20%) R (27%) Ciprofloxacin Oral, IV 75% 4 (10 in anuria) R (50%) M Levofloxacin Oral, IV 98% 7 R (80%) Gatifloxacin Oral, IV 96% 7-8 R (70%) Moxifloxacin Oral, IV 89% 10-14 R (20%) M (25%) (in liver) Nitrofurantoin Oral Adequate 0.6-1.2 R, M (in tissue) Polymyxin B Topical, oral, IV Not absorbed in adults; absorbed in children 6 by IV R M, Metabolized; R, renal excretion as unchanged drug.
Quinolones
Disease Recommendations RESPIRATORY TRACT INFECTIONS Pharyngitis, otitis media Not appropriate Necrotizing otitis Ciprofloxacin for Pseudomonas aeruginosa Sinusitis Third-generation fluoroquinolone Community-acquired pneumonia Third-generation fluoroquinolone Hospital-acquired pneumonia Ciprofloxacin, for susceptible gram- negative pathogens URINARY TRACT INFECTIONS Cystitis, uncomplicated All effective (second generation most appropriate) Pyelonephritis All effective (second generation most appropriate) Prostatitis All effective SKIN STRUCTURE INFECTIONS Primary cellulitis Not appropriate as first line therapy Anaerobic soft-tissue infections Not appropriate
Disease Recommendations OSTEOMYELITIS Gram-negative bacterial infections Ciprofloxacin BACTERIAL DIARRHEAL DISEASES Ciprofloxacin used most commonly; all considered likely to be effective SEXUALLY TRANSMITTED DISEASES Gonorrhea Resistance testing required Chlamydia Ofloxacin, levofloxacin Chancroid All likely to be effective Mycoplasma Ofloxacin, levofloxacin Syphilis Not appropriate MYCOBACTERIAL DISEASES Disseminated M. avium complex Ciprofloxacin, ofloxacin as fourth agent if needed M. tuberculosis Ofloxacin, levofloxacin for drug- resistance or intolerance to first- line agents
Quinolones
 Gastrointestinal effects  Central nervous system agitation (rarely seizures)  Damage to growing cartilage (not recommended for use in children)  Theophylline interaction (with ciprofloxacin)
Quinolones and fluoroquinolones