Is oral minoxidil safe to use with Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide)?

Safety of Oral Minoxidil with Biktarvy

Oral minoxidil is likely safe to use with Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide) as there are no documented significant drug-drug interactions between these medications.

Drug Interaction Analysis

Biktarvy contains three components:

• Bictegravir: An integrase strand transfer inhibitor (INSTI)
• Emtricitabine: A nucleoside reverse transcriptase inhibitor (NRTI)
• Tenofovir alafenamide: A nucleotide reverse transcriptase inhibitor (NRTI)

Metabolism and Drug Interaction Pathways

1. Biktarvy metabolism:

   • Bictegravir is primarily metabolized by CYP3A4 and UGT1A1 1
   • Emtricitabine and tenofovir alafenamide are not significantly metabolized through the CYP450 pathway 1
   • Bictegravir is transported by P-gp and BCRP 2

2. Minoxidil metabolism:

   • Oral minoxidil is primarily metabolized by hepatic enzymes but not through the CYP450 pathway
   • It does not act as an inducer or inhibitor of P-gp or CYP enzymes 3, 4

Evidence for Safety

The International Antiviral Society-USA guidelines specifically note that antiretroviral drugs metabolized independently of the CYP450 pathway (like Biktarvy) have fewer drug-drug interactions 2. While the guidelines don't specifically mention minoxidil, they emphasize that INSTIs like bictegravir have favorable drug interaction profiles.

The guidelines state: "Any antiretroviral drugs that are metabolized independently of the CYP450 pathway (eg, raltegravir-, dolutegravir- or bictegravir-based regimens) are recommended to minimize drug-drug interactions" 2.

Safety Profile of Low-Dose Oral Minoxidil

Low-dose oral minoxidil (LDOM) has been studied extensively for hair loss treatment:

• In a multicenter study of 1,404 patients, LDOM demonstrated a good safety profile 4
• Common side effects included:
  • Hypertrichosis (15.1%)
  • Lightheadedness (1.7%)
  • Fluid retention (1.3%)
  • Tachycardia (0.9%)
  • Headache (0.4%)
  • Periorbital edema (0.3%)
  • Insomnia (0.2%)
• No life-threatening adverse effects were observed 4

Monitoring Recommendations

When using oral minoxidil with Biktarvy, the following monitoring is advised:

1. Blood pressure monitoring: Oral minoxidil can cause hypotension, so regular blood pressure checks are recommended
2. Cardiovascular assessment: Monitor for signs of fluid retention or tachycardia
3. Renal function: Regular monitoring of renal function is already recommended for patients on Biktarvy, especially important since minoxidil can cause fluid retention 2

Practical Recommendations

1. Start with low-dose minoxidil: Begin with 2.5mg daily and titrate up if needed and tolerated
2. Monitor for side effects: Pay particular attention to cardiovascular effects
3. Continue standard HIV monitoring: Follow the usual monitoring schedule for patients on Biktarvy
4. Use the University of Liverpool HIV Drug Interactions website: For ongoing reference regarding potential interactions (https://www.hiv-druginteractions.org/) 2

Conclusion

Based on the available evidence, oral minoxidil can be safely used with Biktarvy as there are no known significant pharmacokinetic interactions between these medications. The main considerations are the independent side effect profiles of each medication rather than drug-drug interactions.