Vitamin B12 and Rifampin Interaction

Key Clinical Considerations

• The American Thoracic Society and Infectious Diseases Society of America recommend pyridoxine 25-50 mg daily to prevent peripheral neuropathy specifically caused by isoniazid, not rifampin 1
• Pyridoxine does NOT prevent rifampin-related hepatotoxicity or other hematological adverse events 1
• High-risk populations, including pregnant women, breastfeeding infants, persons with HIV infection, patients with diabetes mellitus, patients with alcoholism, malnourished patients, patients with chronic renal failure, and elderly patients, should receive pyridoxine 25-50 mg daily 1, 2

Important Drug Interactions to Monitor with Rifampin

• Rifampin is a potent inducer of hepatic cytochrome P450 enzymes, which substantially decreases concentrations of many medications, including antiretrovirals, hormonal contraceptives, anticoagulants, immunosuppressants, cardiovascular drugs, and antifungals 2, 3
• The American Thoracic Society recommends monitoring for drug interactions, including antiretrovirals, hormonal contraceptives, anticoagulants, immunosuppressants, cardiovascular drugs, and antifungals 2

Monitoring Recommendations

• Monthly clinical monitoring is recommended for all patients on rifampin 1
• Baseline liver function tests are recommended in elderly patients, those with pre-existing liver disease, or alcohol consumers 1
• Monitoring for signs of peripheral neuropathy is recommended if isoniazid is used concurrently 1