What is Rifampin (Rifamprin) used for in the treatment of bacterial infections, particularly in patients with a history of tuberculosis or compromised immune systems?

What is Rifampin Used For?

Rifampin is primarily used for the treatment of all forms of tuberculosis (both active disease and latent infection) and for eliminating Neisseria meningitidis from the nasopharynx in asymptomatic carriers. 1

Primary Indications

Active Tuberculosis Treatment

• Rifampin is an essential component of first-line multidrug regimens for treating active TB disease, typically combined with isoniazid, pyrazinamide, and ethambutol in the initial 2-month intensive phase, followed by rifampin plus isoniazid for at least 4 additional months. 1
• The CDC, American Thoracic Society, and Infectious Diseases Society of America recommend a four-drug regimen (rifampin, isoniazid, pyrazinamide, plus either streptomycin or ethambutol) for initial treatment unless community isoniazid resistance rates are less than 4%. 1
• Rifampin and pyrazinamide are essential components that render patients noninfectious rapidly and cure drug-susceptible TB within 6 months. 2
• Treatment duration should be at least 6 months, completing a minimum of 180 daily doses or equivalent intermittent dosing. 3

Latent Tuberculosis Infection (LTBI)

• Rifampin can be used for treating latent TB infection, though the rifampin-pyrazinamide combination for LTBI is generally NOT recommended due to high rates of severe liver injury and death. 2
• The ATS/CDC found hospitalization rates of 3.0 per 1,000 and death rates of 0.9 per 1,000 treatment initiations with rifampin-pyrazinamide for LTBI. 2
• Alternative regimens for LTBI are preferred, such as isoniazid monotherapy or rifampin monotherapy (without pyrazinamide). 2

Meningococcal Carrier State

• Rifampin is indicated for eliminating Neisseria meningitidis from the nasopharynx in asymptomatic carriers, but it is NOT indicated for treating active meningococcal infection due to rapid emergence of resistance. 1
• Rifampin should only be used when the risk of meningococcal disease is high and after diagnostic procedures confirm the carrier state. 1

Critical Usage Considerations in Special Populations

HIV-Infected Patients

• Rifampin can be used in HIV-infected patients taking certain antiretroviral regimens, specifically those containing efavirenz plus two NRTIs, or ritonavir-based regimens. 2
• Rifampin is contraindicated with most protease inhibitors due to severe drug-drug interactions via cytochrome P450 enzyme induction. 2
• Rifampin does not interact with nucleoside reverse transcriptase inhibitors (NRTIs) and requires no dose adjustments when used concurrently. 2
• The risk for progression from latent to active TB is substantially increased in HIV-infected persons, making treatment of LTBI particularly important in this population. 2

Patients with Compromised Immune Systems

• HIV-positive patients with active TB should receive the same multidrug rifampin-containing regimens as HIV-negative patients, though treatment may need to be extended if the patient remains sputum or culture positive. 1
• Careful attention to drug interactions with antiretroviral therapy is essential, with rifabutin often preferred over rifampin in patients requiring protease inhibitors. 2

Important Safety Warnings

Hepatotoxicity Monitoring

• Adults treated with rifampin should have baseline measurements of hepatic enzymes, bilirubin, serum creatinine, complete blood count, and platelet count. 1
• Patients should be monitored monthly and questioned about symptoms of hepatotoxicity (fever, loss of appetite, malaise, nausea, vomiting, darkened urine, jaundice). 1
• The most common adverse reaction is gastrointestinal upset, with other reactions including skin eruptions, hepatitis, and rarely thrombocytopenia. 4

Drug Interactions

• Rifampin is a potent inducer of hepatic cytochrome P450 enzymes (especially CYP3A4) and P-glycoprotein, accelerating metabolism of numerous medications including oral contraceptives, warfarin, anticonvulsants, and immunosuppressants. 3, 1
• Patients should be advised that oral contraceptives may be less reliable and alternative contraceptive measures should be considered. 1

Resistance Prevention

• Rifampin should never be used as monotherapy for any bacterial infection due to rapid development of resistance. 3
• Bacteriologic cultures should be obtained before starting therapy and repeated throughout treatment to monitor response and detect resistance. 1
• Resistant cells can rapidly become predominant within large populations of susceptible organisms. 1

Common Pitfalls to Avoid

• Do NOT use rifampin-pyrazinamide combination for latent TB infection due to unacceptably high rates of severe liver injury and death. 2
• Do NOT use rifampin for skin and soft tissue infections (cellulitis) either as monotherapy or adjunctive therapy. 3
• Do NOT interrupt therapy inadvertently, as intermittent dosing (especially doses >600 mg once or twice weekly) increases risk of "flu syndrome," hematopoietic reactions, and other serious adverse effects. 1
• Warn patients that rifampin causes orange-red discoloration of urine, sweat, tears, and sputum, and may permanently stain soft contact lenses. 1
• Take rifampin either 1 hour before or 2 hours after meals with a full glass of water for optimal absorption. 1