Genvoya Dosing in Renal Impairment
Genvoya (elvitegravir, cobicistat, emtricitabine, tenofovir alafenamide) carries warnings for use in patients with renal impairment due to risks of acute kidney injury and chronic renal effects from its tenofovir component.[1] It is not recommended for patients with estimated creatinine clearance (CrCl) below 30 mL/min, and specific monitoring is required at lower levels.[1]
CrCl Thresholds and Recommendations
- CrCl ≥30 mL/min: Safe with no dose adjustment; monitor serum creatinine, phosphorus, and urine glucose/protein before starting and every 3-6 months.[1]
- CrCl 15-29 mL/min: Avoid initiation in treatment-naive patients; use only in virologically suppressed patients on a stable regimen for ≥3 months, with added monitoring. Discontinue if CrCl falls below 15 mL/min or if abnormalities develop.[1]
- **CrCl <15 mL/min or on dialysis**: Contraindicated; tenofovir alafenamide accumulates, increasing toxicity risk.[1]
These guidelines come from the Genvoya prescribing information, reflecting FDA-approved labeling.[1]
Why Renal Risks Occur
Tenofovir alafenamide (TAF) converts to tenofovir in cells but has lower plasma levels than tenofovir disoproxil fumarate (TDF), reducing renal proximal tubule toxicity. Cobicistat boosts elvitegravir and slightly elevates creatinine via transporter inhibition (not true glomerular filtration loss).[1][2] Still, proximal tubulopathy, Fanconi syndrome, and acute kidney injury occur in 0.1-1% of patients, higher in those with baseline impairment.[1]
Monitoring and Patient Management
Test CrCl using Cockcroft-Gault before initiation, at 4 weeks, then every 3-6 months. Avoid with tenofovir DF-containing drugs or nephrotoxics like NSAIDs. In trials, renal adverse events were low (1-2%) but rose with declining baseline CrCl.[1][3] Switch to alternatives like bictegravir/TAF/FTC if CrCl drops persistently.[2]
Alternatives for Renal Impairment