Biktarvy Side Effects
The most common side effects of Biktarvy are diarrhea (15-18%), nausea (11-24%), and headache (13-16%), with most adverse events being mild to moderate in severity and rarely leading to treatment discontinuation. 1, 2, 3
Common Side Effects (≥5% incidence)
The three most frequently reported adverse reactions across clinical trials are 1:
- Diarrhea: Occurs in 15-18% of patients 2, 3
- Nausea: Occurs in 11-24% of patients, with lower rates in bictegravir-based regimens compared to some comparator regimens 2, 3
- Headache: Occurs in 13-16% of patients 2, 3
Serious but Rare Side Effects
Hepatitis B Exacerbation (Boxed Warning)
Severe acute exacerbations of hepatitis B can occur in patients coinfected with HIV-1 and HBV who discontinue Biktarvy. 1 Close monitoring of hepatic function is mandatory for several months after stopping treatment in these patients, and anti-hepatitis B therapy may be warranted 1.
Renal Toxicity
New onset or worsening renal impairment can occur, requiring assessment of serum creatinine, estimated creatinine clearance, urine glucose, and urine protein at baseline and during therapy. 1 In patients with chronic kidney disease, serum phosphorus should also be monitored 1. Tenofovir alafenamide has significantly reduced renal toxicity compared to tenofovir disoproxil fumarate, particularly when used with pharmacological boosters 4.
Lactic Acidosis and Hepatotoxicity
Lactic acidosis and severe hepatomegaly with steatosis are rare but potentially fatal complications 1. Discontinue Biktarvy immediately if patients develop symptoms or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (weakness, unusual fatigue, unusual muscle pain, shortness of breath, abdominal pain with nausea/vomiting, cold extremities, dizziness, or fast/irregular heartbeat) 1.
Immune Reconstitution Syndrome
Immune reconstitution inflammatory syndrome can occur when starting Biktarvy, as the immune system strengthens and begins fighting previously hidden infections. 1 This may necessitate further evaluation and treatment 1.
Special Considerations for Pre-existing Conditions
Kidney Disease
- Biktarvy is not recommended in patients with estimated creatinine clearance 15 to <30 mL/min, or <15 mL/min who are not receiving chronic hemodialysis 1
- For virologically-suppressed adults with creatinine clearance <15 mL/min on chronic hemodialysis, Biktarvy can be used with dosing after dialysis 1
- Tenofovir alafenamide in Biktarvy has less proximal renal tubular toxicity and smaller reductions in bone mineral density compared to tenofovir disoproxil fumarate 4
Liver Disease
- Biktarvy is not recommended in patients with severe hepatic impairment (Child-Pugh C) 1
- No dose adjustment is required for mild to moderate hepatic impairment 4
- Integrase inhibitors like bictegravir should be used with caution in severe hepatic impairment, though they generally have favorable profiles 4
Tolerability Profile
Bictegravir-based regimens demonstrate superior tolerability compared to some alternative regimens, with lower rates of study drug-related adverse events (20-28% for bictegravir vs 28-40% for dolutegravir-based regimens) 2, 3. Discontinuation due to adverse events is rare, occurring in only 0-2% of patients 2, 3.
Weight and Metabolic Effects
Tenofovir alafenamide is associated with greater weight gain than tenofovir disoproxil fumarate, though the clinical significance remains unclear 4. Tenofovir disoproxil fumarate has lipid-lowering effects not seen with tenofovir alafenamide, resulting in higher lipid levels with Biktarvy 4.
Bone Health
Bone loss occurs with initiation of all antiretroviral regimens but is less pronounced with integrase inhibitor-based therapy like Biktarvy compared to protease inhibitor-containing regimens 4. Tenofovir alafenamide causes less bone mineral density reduction than tenofovir disoproxil fumarate 4.
Drug Resistance and Treatment Failure
No treatment-emergent resistance to any component of Biktarvy has been observed in clinical trials through 96 weeks, demonstrating the high genetic barrier to resistance of bictegravir 2, 5, 3, 6.
Common Pitfalls to Avoid
- Do not use Biktarvy with dofetilide or rifampin (absolute contraindications) 1
- Screen for hepatitis B before initiating Biktarvy and monitor closely if discontinuing in coinfected patients 1
- Timing matters with antacids: Take Biktarvy at least 2 hours before or 6 hours after aluminum/magnesium-containing antacids, or take with food when using iron/calcium supplements 1
- Monitor renal function even in patients with normal baseline kidney function, as progressive nephrotoxicity can occur 7