Snapshot
- A 43-year-old woman presents to the emergency room for fevers and a chronic cough. She has a history of HIV infection and has been using antiretrovirals intermittently. She recently lost her job and has been spacing out her medications in hopes of making it last. She is also currently homeless and relies on homeless shelters around the city. She reports that she has been having low-grade fevers, night sweats, and cough. A chest radiograph shows a cavity in the apex of the right upper lobe and hilar adenopathy. She is started on multi-drug anti-tuberculosis therapy, including rifabutin. (Tuberculosis)
Introduction
- Drugs
- rifampin
- 4 Rs
- RNA polymerase (DNA-dependent) inhibitor
- Ramps up cytochrome P-450 (CYP450) system
- Results in Red body fluids
- Resistance if used alone
- 4 Rs
- rifabutin
- less CYP450 stimulation
- rifampin
- Mechanism of action
- inhibits DNA-dependent RNA polymerase
- penetrates tissue to reach granulomas
- Mechanism of resistance
- mutations in RNA polymerase to prevent drug from binding
- Clinical use
- rifampin
- Mycoplasma tuberculosis (TB)
- always used with other anti-TB drugs (RIPE therapy – Rifampin, Isoniazid, Pyrazinamide, and Ethambutol)
- Mycoplasma leprae
- long-term treatment with dapsone for tuberculoid form
- Haemophilus influenzae type b
- prophylaxis for the exposed
- Mycoplasma tuberculosis (TB)
- rifabutin
- Mycoplasma avium-intracellulare
- adjuvant treatment with azithromycin and ethambutol
- HIV infection
- rifampin reduces protease inhibitor concentrations through CYP450, so rifabutin is used in HIV patients who require a rifamycin drug
- Mycoplasma avium-intracellulare
- rifampin
- Adverse effects
- hepatotoxicity (hepatitis)
- ↑ CYP-450
- red/orange body fluids (benign)
- acute interstitial nephritis