Avonza is a fixed-dose combination antiretroviral medication used in the treatment of HIV-1 infection. Each once-daily tablet contains:

• Tenofovir Disoproxil Fumarate (TDF) 300 mg

• Lamivudine 300 mg

• Efavirenz 400 mg

This combination is part of the first-line antiretroviral therapy (ART) as per WHO guidelines. The use of Efavirenz 400 mg instead of the older 600 mg dose maintains clinical effectiveness with fewer side effects, improving tolerability for long-term use.

Mechanism of Action

Avonza works by attacking the HIV virus at multiple stages of its life cycle through a three-drug synergy:

1. Tenofovir Disoproxil Fumarate (TDF) – Nucleotide Reverse Transcriptase Inhibitor (NtRTI):

   • Mimics a natural nucleotide (adenosine monophosphate).

   • Incorporates into viral DNA, prematurely halting its formation.

2. Lamivudine – Nucleoside Reverse Transcriptase Inhibitor (NRTI):

   • A cytidine analogue that inhibits reverse transcriptase, an essential enzyme for viral replication.

3. Efavirenz 400 mg – Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI):

   • Binds non-competitively to reverse transcriptase.

   • Changes the enzyme’s shape, making it functionally inactive.

This multi-pronged inhibition prevents HIV from multiplying, allowing the immune system to recover and function more effectively.

Uses / Indications

Avonza is indicated for:

• Treatment of HIV-1 infection in adults and adolescents (≥35 kg).

• Often prescribed as initial therapy, especially in resource-limited settings due to its convenience, efficacy, and cost-effectiveness.

Goals of therapy include:

• Viral suppression (undetectable viral load)

• Immune recovery (increased CD4 count)

• Delaying disease progression to AIDS

• Reducing risk of HIV transmission

  Adverse Effects

  While generally well-tolerated, Avonza may cause some side effects. The use of Efavirenz 400 mg (instead of 600 mg) significantly reduces neuropsychiatric side effects without compromising effectiveness.

  Common Side Effects:

  • Headache

  • Dizziness or lightheadedness

  • Insomnia or unusual dreams (milder with 400 mg EFV)

  • Fatigue

  • Nausea, stomach discomfort

  Less Common:

  • Rash

  • Mild anxiety or mood changes

  • Liver enzyme elevations

  • Changes in kidney function (due to TDF)

  • Bone mineral density reduction (with long-term TDF)