What antibiotics are contraindicated with Biktarvy (bictegravir, emtricitabine, tenofovir alafenamide)?

Antibiotics Contraindicated with Biktarvy

Rifamycin antibiotics (rifampin, rifabutin, rifapentine) are contraindicated with Biktarvy due to significant drug-drug interactions that can substantially decrease bictegravir concentrations, potentially leading to loss of virologic response and possible resistance development. 1, 2

Mechanism of Interaction

• Bictegravir, the integrase strand transfer inhibitor (INSTI) component of Biktarvy, is primarily metabolized through UGT1A1 glucuronidation and CYP3A4 oxidation 2
• Rifamycins are potent inducers of both UGT1A1 and CYP3A4 enzymes, which significantly accelerate bictegravir metabolism 2
• This interaction results in substantially decreased bictegravir plasma concentrations, potentially leading to treatment failure 1

Specific Rifamycin Contraindications

• Rifampin: Absolutely contraindicated with Biktarvy due to the most potent enzyme induction effect 1, 2
• Rifabutin: Contraindicated with Biktarvy due to significant reduction in bictegravir levels 1, 2
• Rifapentine: Contraindicated with Biktarvy due to enzyme induction effects similar to other rifamycins 1, 2

Alternative Antiretroviral Options for Tuberculosis Treatment

For patients requiring rifamycin-based tuberculosis treatment, the International Antiviral Society-USA panel recommends the following alternatives to Biktarvy 1:

• Dolutegravir (50 mg twice daily) with tenofovir/emtricitabine during treatment for active tuberculosis with rifamycin-containing regimens 1
• Efavirenz (600 mg) with tenofovir/emtricitabine 1
• If a protease inhibitor regimen must be used, rifabutin (150 mg) should be substituted for rifampin 1

Other Antibiotics with No Significant Interactions

• Doxycycline: No significant interactions with Biktarvy; can be safely co-administered 3
• Macrolide antibiotics (azithromycin): No significant interactions with Biktarvy 1
• Most other common antibiotics (beta-lactams, fluoroquinolones, etc.) do not have significant interactions with Biktarvy due to its minimal effect on CYP450 enzymes 4

Important Clinical Considerations

• When switching from Biktarvy to alternative regimens for tuberculosis treatment, ensure no gaps in antiretroviral coverage to prevent viral rebound 1
• For patients with both HIV and tuberculosis, treatment planning should involve both infectious disease and tuberculosis specialists 1
• Regular monitoring of HIV RNA levels is essential when making any antiretroviral therapy changes 1
• Biktarvy has a high genetic barrier to resistance when used appropriately, but subtherapeutic levels due to drug interactions may compromise this advantage 5

Caution with Other Medications

• While not antibiotics, certain antifungals (ketoconazole, itraconazole) that are potent CYP3A4 inhibitors may increase bictegravir levels, though this is less clinically concerning than the rifamycin interactions 2
• Clarithromycin and erythromycin may potentially increase bictegravir levels through CYP3A4 inhibition, but this interaction is generally not clinically significant enough to warrant dose adjustments 1

By understanding these contraindications and managing them appropriately, clinicians can ensure optimal treatment outcomes for patients requiring both HIV management and antibiotic therapy.