Drug Groups

approved

Description

A semisynthetic antibiotic produced from Streptomyces mediterranei. It has a broad antibacterial spectrum, including activity against several forms of Mycobacterium. In susceptible organisms it inhibits DNA-dependent RNA polymerase activity by forming a stable complex with the enzyme. It thus suppresses the initiation of RNA synthesis. Rifampin is bactericidal, and acts on both intracellular and extracellular organisms. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p1160)

Indication

For the treatment of Tuberculosis and Tuberculosis-related mycobacterial infections.

Pharmacology

Rifampin is an antibiotic that inhibits DNA-dependent RNA polymerase activity in susceptible cells. Specifically, it interacts with bacterial RNA polymerase but does not inhibit the mammalian enzyme. It is bactericidal and has a very broad spectrum of activity against most gram-positive and gram-negative organisms (including Pseudomonas aeruginosa) and specifically Mycobacterium tuberculosis. Because of rapid emergence of resistant bacteria, use is restricted to treatment of mycobacterial infections and a few other indications. Rifampin is well absorbed when taken orally and is distributed widely in body tissues and fluids, including the CSF. It is metabolized in the liver and eliminated in bile and, to a much lesser extent, in urine, but dose adjustments are unnecessary with renal insufficiency.

Toxicity

LD₅₀=1570 mg/kg (rat), chronic exposure may cause nausea and vomiting and unconsciousness

Affected Organisms

Biotransformation

Primarily hepatic, rapidly deacetylated.

Absorption

Well absorbed from gastrointestinal tract.

Half Life

3.35 (+/- 0.66) hours

Protein Binding

89%

Elimination

Less than 30% of the dose is excreted in the urine as rifampin or metabolites.

Clearance

* 0.19 +/- 0.06 L/hr/kg [300 mg IV]
* 0.14 +/- 0.03 L/hr/kg [600 mg IV]

References

External Links