What is the recommended dose of tenofovir (Tenofovir Disoproxil Fumarate (TDF) / Tenofovir Alafenamide (TAF)) for the treatment of hepatitis B in adults?

Tenofovir Dosing for Chronic Hepatitis B in Adults

For adults and adolescents ≥12 years weighing ≥35 kg with chronic hepatitis B, the standard dose is tenofovir disoproxil fumarate (TDF) 300 mg once daily orally, or alternatively tenofovir alafenamide (TAF) 25 mg once daily. 1, 2, 3

Standard Dosing by Formulation

Tenofovir Disoproxil Fumarate (TDF)

• 300 mg once daily for adults and pediatric patients ≥12 years weighing ≥35 kg 1, 3
• Can be taken without regard to food 3
• For adolescents 12-18 years: 8 mg/kg daily (up to 300 mg maximum) 1

Tenofovir Alafenamide (TAF)

• 25 mg once daily as an alternative prodrug with improved safety profile 1, 2, 4
• Demonstrates noninferior efficacy to TDF at 48,96, and 144 weeks 2, 5, 6
• Preferred in patients with renal or bone concerns due to superior safety profile 4, 5, 6

Dose Adjustments for Renal Impairment (TDF Only)

Critical renal monitoring is essential as tenofovir is primarily renally eliminated. 1, 2

• CrCl 30-49 mL/min: 300 mg every 48 hours 1, 3
• CrCl 10-29 mL/min: 300 mg every 72-96 hours 3
• Hemodialysis: 300 mg every 7 days or after approximately 12 hours of dialysis 3
• TAF: Safe in patients with CrCl >15 mL/min but not currently recommended below this threshold 4, 7

Critical Safety Monitoring Requirements

Before Initiating Treatment

• Assess baseline creatinine clearance, serum phosphorus, urine glucose, and urine protein 1, 2, 3
• Test for HIV prior to treatment initiation 1
• Consider bone mineral density assessment in patients with history of pathologic fracture or osteoporosis risk factors 3

During Treatment

• Monitor creatinine clearance and serum phosphorus at least annually in patients at risk for renal impairment 1
• In patients at risk for renal dysfunction, monitor estimated creatinine clearance, serum phosphorus, urine glucose, and urine protein periodically 3
• Avoid concurrent or recent use of nephrotoxic drugs 3

Severe Boxed Warning: Post-Treatment Hepatitis Exacerbation

Severe acute exacerbations of hepatitis can occur after discontinuing tenofovir. 2, 3

• Monitor hepatic function closely with clinical and laboratory follow-up for at least several months after discontinuation 2, 3
• If appropriate, resumption of anti-hepatitis B therapy may be warranted 3

TAF vs TDF: Safety Advantages

TAF offers significant renal and bone safety advantages over TDF while maintaining equivalent efficacy. 4, 5, 6

• At 5 years, TAF showed median estimated glomerular filtration rate decline <2.5 mL/min and mean bone mineral density declines <1% at hip and spine 5
• Patients switching from TDF to TAF demonstrated improvements in bone mineral density (hip +0.66% vs -0.51%, spine +1.74% vs -0.11%) and creatinine clearance at 48 weeks 6
• No viral resistance developed with either formulation through 5 years of treatment 5

Common Pitfalls to Avoid

• Never use TDF with other tenofovir-containing products (e.g., TRUVADA, VEMLIDY) or in combination with adefovir 3
• Do not overlook renal monitoring in patients at risk—new onset or worsening renal impairment can include acute renal failure and Fanconi syndrome 3
• Ensure HIV testing before initiating therapy; if HIV-positive, tenofovir must be used as part of appropriate antiretroviral combination regimen, not as monotherapy 1, 3
• Consider TAF over TDF in patients with pre-existing renal impairment, bone disease, or risk factors for these conditions 4, 7, 6

Special Populations

• Pregnancy: TDF is pregnancy category B; TAF has more detailed pregnancy/lactation labeling 1, 2
• Hepatic impairment: TAF is safe in mild hepatic impairment but not recommended in moderate or severe hepatic impairment (Child-Pugh class B or C) 4
• Pediatric patients <12 years or <35 kg: Dosing differs; refer to weight-based dosing guidelines 1