Fluoroquinolone dosage

Pneumococcal resistance to fluoroquinolones may involve changes in topoisomerase IV Modification of fluoroquinolone dosage is required in patients if creatinine clearance is less than 50 mL/min... 

Clinicians should be aware that dosage regimens with the same drug maybe different depending on the infectious process. For example, ciprofloxacin, a fluoroquinolone, has various dosage regimens based on site of infection. The dosing for uncomplicated UTIs is 250 mg twice daily for 3 days. For complicated UTIs, the dose is 500 mg twice daily for 7 to... 

Absorption of antimicrobial agents such as fluoroquinolones and tetracyclines that can be bound by divalent and trivalent cations potentially could be compromised by administration with EN formulas containing these cations. The fluoroquinolones (e.g., levofloxacin and ciprofloxacin) have been best studied in this regard, and results of studies are not consistent. Mechanisms for an interaction between fluoroquinolones and EN formulas other than chelation by cations have been postulated.40 Some institutions hold tube feedings for 30 to 60 minutes or more before and after enteral dosages of fluoroquinolones. Because ciprofloxacin absorption has been shown to be decreased with jejunal administration, this drug probably should not be given by jejunal tube.41... 

Factors directly related to the drug selection include an inappropriate selection of drug, dosage, or route of administration. Malabsorption of a drug product because of GI disease (e.g., short-bowel syndrome) or a drug interaction (e.g., complexation of fluoroquinolones with multivalent cations resulting in reduced absorption) may lead to potentially subtherapeu-tic serum concentrations. 

Factors that may decrease theophylline clearance and lead to reduced dosage requirements include advanced age, bacterial or viral pneumonia, heart failure, liver dysfunction, hypoxemia from acute decompensation, and use of drugs such as cimetidine, macrolides, and fluoroquinolone antibiotics. 

Danofloxacin is a fluoroquinolone antibacterial developed specifically for use in veterinary medicine (140). It has been studied for use in cattle, swine, chickens, and turkeys for the control of respiratory and enteric bacterial infections (141). Danofloxacin can be administered via drinking water to broiler chickens and replacement chicks at a dosage of 5 mg/kg bw for 3 days, and via the intramuscular route to calves, beef, and nonlactating cattle at a dosage of 1.25 mg/kg bw/ day for 3 days. 

Marbofloxacin is a new fluoroquinolone intended for treatment of bovine respiratory disease by the oral or parenteral route, and for treatment of the mastitis-metritis-agalactia syndrome in pigs by the parenteral route. The proposed dosage rate is 2 mg/kg bw/day for up to 5 days. 

Aly et al. [16] reported a rapid and sensitive chemiluminescence (CL) method for the determination of three fluoroquinolone derivatives, including ciprofloxacin, in both pharmaceutical dosage forms and in biological fluids. The method is based on the CL reaction of the drugs with tris(2,2 -bipyridyl)ruthenium(II) and cerium(IV) in sulfuric acid medium. The CL intensity was proportional to the concentration of ciprofloxacin in solution over the range 0.05-6 pg/mL, and the limit of detection was reported to be 26 nM. 

Topical administration of the fluoroquinolones to immature animals does not cause arthropathy, and the ophthalmic dosage form does not appear to affect the weight-bearing joints in humans. All the topical ophthalmic fluoroquinolones, except levofloxacin, are approved for use in patients 1 year of age and older. 

Leukopenia has been observed in 0.1-0.7% of patients given fluoroquinolones in Japan and eosinophilia was observed in 0.5-2.2% of these patients (42). Leukopenia was generally mild and reversible after dosage reduction or withdrawal (43,44). 

Fluoroquinolones are potent inhibitors of hepatic cytochrome P450 isozymes (150). They inhibit theophylline metabolism, and accumulation of theophylline has led to seizures (151). Theophylline clearance is reduced by about 10% by norfloxacin, 30% by ciprofloxacin, and 70% by enoxacin (152-162). In a comparison of grepa-floxacin (400 and 600 mg/day) and ciprofloxacin, increased theophylline concentrations associated with clinical symptoms were found with both doses of grepa-floxacin but not in patients taking ciprofloxacin (17). The dosage of theophylline should be reduced when a quino-lone is given. 

The clinical effectiveness of aminoglycosides and fluoroquinolones is influenced both by the height of the peak plasma concentration relative to the minimum inhibitory concentration (Cmax MIC ratio) and the area under the plasma concentration-time curve that is above the MIC during the dosage interval (AUIC = AUC/MIC). The former is relatively more important for fluoroquinolones maximum activity is achieved when Cmax is in the range 5-10 times the MIC. 

Other fluoroquinolones can be substituted at doses appropriate for age. Ciprofloxacin dosage should not exceed 1 g d" in children... 

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