Cirok Mechanism of Action

Pharmacology: Pharmacodynamics: Activity: Ciprofloxacin is a synthetic 4-quinolone derivative antibacterial agent of the fluoroquinolone class.
Mechanism of action: As a fluoroquinolone antibacterial agent, ciprofloxacin acts on the DNA-DNA-gyrase complex and topoisomerase IV.
Pharmacokinetics: Absorption: After oral administration, ciprofloxacin is predominantly absorbed from the duodenum and upper jejunum, and reaches peak serum concentrations within 60-90 min. After single doses of 250 mg and 500 mg C_max values are about 0.8-2.0 mg/1 L and 1.5-2.9 mg/1 L respectively.
The absolute bioavailability is approximately 70 to 80%. C_max- and AUC-values are proportionally increased with the dose.
Food intake has no effect on the plasma concentration profile of ciprofloxacin.
Distribution: The steady-state volume of distribution of ciprofloxacin is 2-3 L/kg. Since the protein binding of ciprofloxacin is low (20-30%) and the substance is predominantly present in the blood plasma in non-ionized form, almost the entire quantity of the administered dose can diffuse freely into the extravasal space. As a result, the concentrations in certain body fluids and tissues may be markedly higher than the corresponding serum concentrations.
Metabolism/Elimination: Ciprofloxacin is essentially excreted in unchanged form, mostly in the urine. Renal clearance lies between 3 and 5 mL/min/kg, and total clearance amounts to 8-10 mL/min/kg. Both glomerular filtration and tubular secretion play a part in the elimination of ciprofloxacin.
Small concentrations of 4 metabolites were found: desethylene ciprofloxacin (M 1), sulphociprofloxacin (M 2), oxociprofloxacin (M 3) and formylciprofloxacin (M 4). M 1 to M 3 show antibacterial activity comparable with or smaller than nalidixic acid. M 4 with the lowest quantity, has an antimicrobial activity very much corresponding to norfloxacin. (See Table 1.)

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The half-life of ciprofloxacin lies between 3 and 5 hours, both after oral and after intravenous administration. Since ciprofloxacin is excreted not only via the kidneys, but also to a major extent via the gut, renal function must be substantially impaired before increases in serum elimination half-life of up to 12 hours are observed.