From the Guidelines
Azithromycin is the preferred first-line medication for MAC prophylaxis, typically given at a dose of 1200 mg once weekly or 600 mg twice weekly, due to its efficacy and safety profile as supported by the most recent guidelines 1.
Key Considerations for MAC Prophylaxis
- MAC prophylaxis is primarily recommended for HIV-infected patients with CD4 counts below 50 cells/μL, as they are at highest risk for disseminated MAC disease.
- Clarithromycin is an alternative option, usually prescribed at 500 mg twice daily, for patients who cannot tolerate azithromycin.
- Prophylaxis should be continued until immune reconstitution occurs with CD4 counts consistently above 100 cells/μL for at least 3 months on effective antiretroviral therapy.
- Before starting prophylaxis, it's essential to rule out active MAC disease by obtaining blood cultures if symptoms are present, and to exclude active tuberculosis to prevent rifampin resistance when using rifabutin as an alternative 1.
Choosing the Best Medication
- Azithromycin and clarithromycin are preferred due to their direct antimycobacterial activity and their ability to concentrate within macrophages where MAC organisms reside.
- Rifabutin (300 mg daily) can be considered as an alternative for patients who cannot tolerate macrolides, though it has more side effects and drug interactions, which should be carefully monitored 1.
Monitoring and Side Effects
- Common side effects of macrolide antibiotics include gastrointestinal disturbances.
- Drug interactions should be monitored, particularly with medications metabolized through the cytochrome P450 system, to ensure safe and effective treatment 1.
From the FDA Drug Label
ANTI-MAC (Mycobacterium avium intracellulare complex) Azithromycin 500 mg once a day for 1 day, then 250 mg once a day for 9 days 300 mg once a day Healthy subjects (6) ↔ ↔ Clarithromycin 500 mg twice a day 300 mg once a day HIV-infected patients (12) ↑ AUC by 75% ↓ AUC by 50% Monitor for rifabutin associated adverse events Reduce dose or suspend use of rifabutin if toxicity is suspected. Alternative treatment for clarithromycin should be considered when treating patients receiving rifabutin
The best medications for MAC prophylaxis are Azithromycin and Clarithromycin.
- Azithromycin has been shown to have no significant interaction with rifabutin, making it a suitable option.
- Clarithromycin has an increased risk of uveitis when co-administered with rifabutin, and its use should be monitored closely for adverse reactions. It is recommended to monitor for rifabutin associated adverse events and consider alternative treatments when using Clarithromycin. 2 3
From the Research
Medications for MAC Prophylaxis
The following medications have been studied for MAC prophylaxis:
- Clarithromycin: shown to prevent the development of MAC bacteraemia in patients with advanced HIV disease 4, 5
- Azithromycin: also shown to prevent MAC bacteraemia, and may be less likely to result in the emergence of resistance than clarithromycin 4, 6, 7
- Rifabutin: has been used as a prophylactic agent for MAC, but may be less effective than clarithromycin or azithromycin 4, 6, 5
Combination Therapy
Combination therapy with clarithromycin and rifabutin has been studied, but was found to be not more effective than clarithromycin alone, and was associated with more adverse effects 5
- Azithromycin plus rifabutin was also studied, and was found to be more effective than either agent alone, but caused frequent gastrointestinal adverse events 4
Current Recommendations
Current recommendations for MAC prophylaxis include: