Explain Rifabutin
Two alternative regimens are based on the fact that rifabutin appears to be as effective as rifampin against TB, and has less effect on protease inhibitor levels. The first substitutes low-dose rifabutin (150 mg once/day or 300 mg 3x/week) for rifampin in the standard regimen (i.e., isoniazid, rifabutin, pyrazinamide and ethambutol) and uses higher than usual doses of indinavir (Crixivan) or nelfinavir (Viracept), or standard doses of amprenavir (Agenerase) or fos amprenavir (Lexiva) as the protease inhibitor.
The second decreases the rifabutin dose further to 150 mg every other day or 3 times weekly and gives it with standard doses of atazanavir (Reyataz), ritonavir/lopinavir (Kaletra) or ritonavir alone or combined with other protease inhibitors. Saquinavir (Fortovase, Invirase) alone should not be used. If the HAART regimen contains nevirapine, the usual dose of rifabutin should be used. Higher rifabutin doses (450-600 mg daily) are needed if the HAART regimen contains efavirenz.