What is the recommended dose of Tenofovir (Antiretroviral medication) for the treatment of chronic hepatitis B?

Tenofovir Dosing for Chronic Hepatitis B

The recommended dose of tenofovir disoproxil fumarate (TDF) for chronic hepatitis B is 300 mg orally once daily in adults and pediatric patients ≥12 years of age weighing ≥35 kg, with dose adjustments required for renal impairment. 1

Standard Dosing by Age and Weight

Adults and Adolescents (≥12 years, ≥35 kg)

• 300 mg once daily taken orally without regard to food 1
• This dosing applies to both HBeAg-positive and HBeAg-negative chronic hepatitis B 2
• The optimal duration of treatment is unknown, but long-term therapy is typically required 1

Adolescents (12-18 years)

• TDF 300 mg once daily is approved for patients ≥12 years and ≥35 kg 2, 1
• Alternative: Tenofovir alafenamide (TAF) 8 mg/kg daily (up to 300 mg) for those ≥12 years 2
• Clinical trial data showed 89% virological response at week 72 with no resistance development 2

Pediatric Patients (<12 years)

• Safety and efficacy not established for chronic hepatitis B in children <12 years 1
• TDF is only approved for HIV treatment (not HBV) in children 2-11 years at 8 mg/kg daily (maximum 300 mg) 1

Dose Adjustments for Renal Impairment

Renal function monitoring is critical as tenofovir is primarily renally eliminated 2, 1:

• CrCl ≥50 mL/min: No adjustment needed; 300 mg once daily 1
• CrCl 30-49 mL/min: 300 mg every 48 hours 1
• CrCl 10-29 mL/min: 300 mg every 72-96 hours 1
• Hemodialysis: 300 mg every 7 days or after approximately 12 hours of dialysis 1

Important Monitoring Considerations

• Assess baseline creatinine clearance, serum phosphorus, urine glucose, and urine protein before initiating therapy 2, 1
• Continue routine monitoring during treatment, especially in patients with mild renal impairment (CrCl 50-80 mL/min) 1
• The dosing interval adjustments are based on pharmacokinetic modeling and have not been clinically validated in patients with moderate-severe renal impairment 1

Alternative Tenofovir Formulation: TAF

Tenofovir alafenamide (TAF) 25 mg once daily is an alternative prodrug with improved safety profile 2:

• Approved for adults with chronic HBV and compensated liver disease 3
• Demonstrated noninferior efficacy to TDF at 48,96, and 144 weeks 3, 4, 5
• Superior bone and renal safety compared to TDF, with significantly smaller declines in bone mineral density and estimated GFR 4, 5
• More than 90% lower systemic tenofovir exposure than TDF 6, 5
• Safe in patients with CrCl >15 mL/min, though not currently recommended below this threshold 3

Critical Safety Warnings

Post-Treatment Hepatitis Exacerbation

Severe acute exacerbations of hepatitis can occur after discontinuing tenofovir 1:

• Monitor hepatic function closely with clinical and laboratory follow-up for at least several months after discontinuation 1
• Consider resuming anti-HBV therapy if exacerbation occurs 1

Special Populations

• Decompensated cirrhosis: TDF was evaluated in limited numbers; use with caution and coordinate with transplant centers 1
• Pregnancy: TDF is pregnancy category B; TAF has more detailed pregnancy/lactation labeling 2
• HIV coinfection: Do not use TDF alone; must be combined with other antiretrovirals 1

Common Pitfalls to Avoid

1. Failing to adjust dose for renal impairment - Always calculate CrCl before initiating therapy 1
2. Using TDF in children <12 years for HBV - Not approved for this indication 1
3. Abrupt discontinuation without monitoring - Risk of severe hepatitis flares 1
4. Inadequate renal/bone monitoring - Essential for long-term safety, particularly with TDF 2, 1