Introduction
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)
Uses
Rifcin Syrup 100 mg/5 ml is an antibiotic used to treat several types of mycobacterial infections including Mycobacterium avium complex, leprosy, and in combination with other antibacterials to treat latent or active tuberculosis.
For the treatment of Tuberculosis and Tuberculosis-related mycobacterial infections.
Associated Conditions
Pharmacodynamics
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.
Mechanism of Action
Rifampin acts via the inhibition of DNA-dependent RNA polymerase, leading to a suppression of RNA synthesis and cell death.
Absorption
Well absorbed from gastrointestinal tract.
Protein Binding
89%
Route of Elimination
Less than 30% of the dose is excreted in the urine as rifampin or metabolites.
Half Life
3.35 (+/- 0.66) hours
Clearance
- 0.19 +/- 0.06 L/hr/kg [300 mg IV]
- 0.14 +/- 0.03 L/hr/kg [600 mg IV]
Toxicity
LD50=1570 mg/kg (rat), chronic exposure may cause nausea and vomiting and unconsciousness
Food Interactions
- Avoid alcohol.
- Take on an empty stomach. Take at least 1 hour before or 2 hours after meals.
- Take with a full glass of water.
Dosage
Tuberculosis:
- Adults: 10 mg/kg, in a single daily administration, not to exceed 600 mg/day, oral or IV
- Pediatric Patients: 10–20 mg/kg, not to exceed 600 mg/day, oral or IV
Rifampin is indicated in the treatment of all forms of tuberculosis. A three-drug regimen consisting of rifampin, isoniazid, and pyrazinamide is recommended in the initial phase of shortcourse therapy which is usually continued for 2 months. The Advisory Council for the Elimination of Tuberculosis, the American Thoracic Society, and the Centers for Disease Control and Prevention recommend that either streptomycin or ethambutol be added as a fourth drug in a regimen containing isoniazid (INH), rifampin and pyrazinamide for initial treatment of tuberculosis unless the likelihood of INH resistance is very low. The need for a fourth drug should be reassessed when the results of susceptibility testing are known. If community rates of INH resistance are currently less than 4%, an initial treatment regimen with less than four drugs may be considered.
Following the initial phase, treatment should be continued with rifampin and isoniazid for at least 4 months. Treatment should be continued for longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV positive.
