Source: Υπουργείο Υγείας (CY) Revision Year: 2018 Publisher: Remedica Ltd., Aharnon Str., Limassol Industrial Estate, 3056 Limassol, Cyprus
Pharmacotherapeutic group: Antimycobacterials, drugs for treatment of tuberculosis
ATC code: J04AB02
Rifampicin is an active bactericidal antituberculosis drug which is particularly active against the rapidly growing extracellular organisms and also has bactericidal activity intracellularly. Rifampicin has activity against slow and intermittently-growing M. Tuberculosis.
Rifampicin inhibits DNA-dependent RNA polymerase activity in susceptible cells. Specifically, it interacts with bacterial RNA polymerase but does not inhibit the mammalian enzyme. Cross-resistance to rifampicin has only been shown with other rifamycins.
Rifampicin is readily absorbed from the gastrointestinal tract. Peak serum concentrations of the order of 10 μg/ml occur about 2 to 4 hours after a dose of 10 mg/kg body weight on an empty stomach.
Absorption of rifampicin is reduced when the drug is ingested with food. The pharmacokinetics (oral and intravenous) in children are similar to adults. In normal subjects the biological half-life of rifampicin in serum averages about 3 hours after a 600 mg dose and increases to 5.1 hours after a 900 mg dose. With repeated administration, the half-life decreases and reaches average values of approximately 2-3 hours. At a dose of up to 600 mg/day, it does not differ in patients with renal failure and consequently, no dosage adjustment is required.
Rifampicin is rapidly eliminated in the bile and an enterohepatic circulation ensues. During this process, rifampicin undergoes progressive deacetylation, so that nearly all the drug in the bile is in this form in about 6 hours. This metabolite retains essentially complete antibacterial activity. Intestinal reabsorption is reduced by deacetylation and elimination is facilitated. Up to 30% of a dose is excreted in the urine, with about half of this being unchanged drug.
Rifampicin is widely distributed throughout the body. It is present in effective concentrations in many organs and body fluids, including cerebrospinal fluid. Rifampicin is about 80% protein bound. Most of the unbound fraction is not ionized and therefore is diffused freely in tissues.
Not applicable.
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