clarithromycin + rifabutin

Clarithromycin + rifabutin is a combination of two antibiotics used primarily for the treatment and prophylaxis of infections caused by *Mycobacterium avium* complex (MAC), particularly in immunocompromised patients such as those with HIV/AIDS. Clarithromycin is a macrolide antibiotic that inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit. Rifabutin is a rifamycin derivative that inhibits DNA-dependent RNA polymerase in susceptible bacteria, thereby suppressing RNA synthesis and subsequent protein production. The combination targets MAC through dual mechanisms but is associated with significant pharmacokinetic interactions due to opposing effects on cytochrome P450 enzymes—clarithromycin inhibits CYP3A4 while rifabutin induces it—which can alter drug levels and increase adverse effects such as uveitis and gastrointestinal symptoms[1][4][5]. This regimen has also been studied for use in Crohn's disease related to suspected mycobacterial infection, though sustained benefit was not demonstrated[3].