## First-Line Antiviral for HBV with Cirrhosis **Key Point:** Tenofovir disoproxil fumarate (TDF) is the preferred first-line nucleotide reverse transcriptase inhibitor (NtRTI) for HBV treatment, particularly in patients with cirrhosis and high viral loads. ## Why Tenofovir is Preferred | Feature | Tenofovir | Lamivudine | Adefovir | Entecavir | |---------|-----------|-----------|---------|----------| | **Barrier to resistance** | High | Low | Moderate | High | | **HBV DNA suppression** | Excellent | Good | Good | Excellent | | **Resistance rate (1 yr)** | <1% | 70% | <1% | <1% | | **Use in cirrhosis** | Preferred | Avoid monotherapy | Alternative | Alternative | | **Renal monitoring** | Required | Not needed | Required | Not needed | | **Cost (India)** | Moderate | Low | Moderate | Low | **High-Yield:** Tenofovir is a nucleotide analog (not nucleoside) — it has the highest genetic barrier to resistance among all oral antivirals for HBV. It is the WHO-recommended first-line agent globally. **Clinical Pearl:** In a patient with cirrhosis and HBeAg positivity with high HBV DNA (>10^5 copies/mL), monotherapy with lamivudine is contraindicated due to rapid emergence of resistance (YMDD mutations). Tenofovir or entecavir monotherapy are both acceptable, but tenofovir is preferred as first-line in most guidelines due to superior resistance profile. **Warning:** Lamivudine monotherapy leads to resistance in >70% of patients by 1 year — never use as monotherapy in treatment-naïve patients with high viral loads. ## Treatment Algorithm for HBV ```mermaid flowchart TD A[HBsAg+ with indication for treatment]:::outcome --> B{Cirrhosis present?}:::decision B -->|Yes| C[High barrier to resistance agent]:::action B -->|No| D{HBV DNA level & ALT}:::decision C --> E[Tenofovir or Entecavir]:::action D --> F[Assess for treatment need]:::action E --> G[Monitor HBV DNA & renal function]:::action F --> G ``` [cite:Harrison 21e Ch 297]
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