Tenofovir Disoproxil Fumarate Renal Dose Adjustment
For tenofovir disoproxil fumarate (TDF), dose adjustment is mandatory when creatinine clearance falls below 50 mL/min: administer 300 mg every 48 hours for CrCl 30-49 mL/min, every 72-96 hours for CrCl 10-29 mL/min, and once weekly (or after dialysis) for hemodialysis patients; TDF is not recommended when CrCl is below 10 mL/min without dialysis. 1
Standard Dosing Schedule by Renal Function
The FDA-approved dose adjustments for TDF based on creatinine clearance are:
| Creatinine Clearance | TDF Dosing Interval |
|---|---|
| ≥50 mL/min | 300 mg every 24 hours |
| 30-49 mL/min | 300 mg every 48 hours |
| 10-29 mL/min | 300 mg every 72-96 hours |
| <10 mL/min (no dialysis) | Not recommended |
| Hemodialysis | 300 mg once weekly or after ~12 hours of dialysis |
No dose adjustment is required for mild renal impairment (CrCl 50-80 mL/min). 1
When to Avoid TDF Entirely
**TDF should not be initiated in patients with baseline eGFR <60 mL/min/1.73 m²—instead, use tenofovir alafenamide (TAF), entecavir, or besifovir.** 3, 2 This recommendation is based on large phase 3 trials showing that patients with risk factors for renal dysfunction (age >50 years, hypertension, diabetes, cardiovascular disease) experienced significantly worse renal outcomes on TDF compared to TAF (median eGFR decline of -5.0 mL/min versus -0.3 mL/min over 96 weeks). 2, 3
Additional contraindications to TDF initiation include:
- Proteinuria or urine albumin-to-creatinine ratio >30 mg/g 3, 2
- Serum phosphate <2.5 mg/dL 3, 2
- Uncontrolled diabetes or hypertension 3, 2
- Osteopenia or osteoporosis 3, 2
Preferred Alternatives in Renal Impairment
When renal function is compromised, the following agents are preferred over TDF:
Tenofovir Alafenamide (TAF)
- Dosing: 25 mg once daily for CrCl ≥15 mL/min 3, 4
- Contraindication: CrCl <15 mL/min without dialysis 2, 3, 4
- Advantage: Minimal impact on renal function compared to TDF 2, 3
Entecavir (for treatment-naïve patients)
- CrCl ≥50 mL/min: 0.5 mg once daily 2, 3
- CrCl 30-49 mL/min: 0.25 mg once daily or 0.5 mg every 48 hours 2, 3
- CrCl 10-29 mL/min: 0.15 mg once daily or 0.5 mg every 72 hours 2, 3
- CrCl <10 mL/min or hemodialysis: 0.05 mg once daily or 0.5 mg every 7 days 2, 3
Besifovir
- CrCl ≥50 mL/min: 150 mg once daily 3, 4
- CrCl 30-49 mL/min: 150 mg every 48 hours 4
- CrCl 15-29 mL/min: 150 mg every 96 hours 4
- Contraindication: CrCl <15 mL/min 3, 4
Switching from TDF to Alternative Agents
If renal function deteriorates on TDF (eGFR drops >25% and falls below 50 mL/min/1.73 m²), switch to TAF, entecavir, or besifovir rather than simply adjusting the TDF dose. 3, 2 This strategy provides superior renal recovery:
- TDF→TAF (48 weeks): eGFR improved by +0.94 mL/min versus continued decline of -2.74 mL/min with TDF 4
- TDF→TAF (96 weeks): eGFR improved by +4.2 mL/min versus -0.9 mL/min with continued TDF 4
- TDF→Besifovir (144 weeks): eGFR returned to baseline versus -7.8 mL/min decline at week 48 with TDF 2, 4
Monitoring Requirements
Before initiating TDF and during therapy, assess serum creatinine, estimated creatinine clearance, urine glucose, and urine protein on a clinically appropriate schedule. 1 In patients with chronic kidney disease, also monitor serum phosphorus. 1
Monitor renal function every 3-6 months in stable patients, and more frequently (every 1-3 months) in those with established CKD or risk factors for kidney disease. 5
Red flags requiring immediate intervention:
- eGFR decline >25% from baseline and drops to <50 mL/min/1.73 m² 5
- New or worsening proteinuria/albuminuria 3, 2
- Euglycemic glycosuria (suggests proximal tubular dysfunction) 6, 5
- Serum phosphate <2.5 mg/dL 3, 2
Clinical Pitfalls to Avoid
Do not continue full-dose TDF (300 mg daily) when CrCl falls below 50 mL/min—this leads to excessive drug accumulation and increased nephrotoxicity risk. 1, 7 Pharmacokinetic studies demonstrate that subjects with CrCl <50 mL/min have substantially reduced tenofovir renal clearance and significantly increased drug exposures. 7
Do not use extended dosing intervals (every 72-96 hours) without considering daily alternatives. Recent population pharmacokinetic simulations show that smaller daily doses (150 mg daily for moderate impairment, 75-100 mg daily for severe impairment) maintain more consistent drug exposure and reduce variability compared to extended-interval dosing. 8 However, these daily low-dose regimens are not yet FDA-approved and require further clinical validation. 8
Do not assume TDF is the cause of renal dysfunction without excluding other etiologies. Common alternative causes include HIV-associated nephropathy, hypertension, diabetes, concomitant nephrotoxic medications (especially ritonavir-boosted protease inhibitors), and volume depletion. 5
Do not use TDF alone in patients with HIV/HBV coinfection—this can select for HIV resistance. 2 TDF must be combined with other antiretrovirals for HIV treatment. 1
Evidence for Dose Adjustment Efficacy
A randomized controlled trial in chronic hepatitis B patients with TDF-induced moderate renal impairment compared 300 mg every 48 hours versus every 72 hours. 9 Both regimens maintained virological suppression without breakthrough over 12 months, but the every-72-hour group showed greater improvement in eGFR (higher proportion achieved eGFR >60 mL/min/1.73 m²). 9 This supports more aggressive dose reduction when renal function is compromised.
A smaller study of HIV patients with TDF dose adjustment to every 48 hours (due to eGFR <60 mL/min/1.73 m² or tenofovir trough >90 ng/mL) demonstrated significant eGFR improvement at 3 months (61.1 to 72.8 mL/min/1.73 m²) while maintaining antiviral efficacy. 10 Concomitantly, tenofovir trough concentrations decreased from 175 to 66 ng/mL. 10
Pediatric Considerations
No data are available to make dosage recommendations in pediatric patients with renal impairment. 1 In children with normal renal function, the recommended dose is 8 mg/kg once daily (maximum 300 mg). 1