# Enfuvirtide

> Enfuvirtide is a synthetic 36-amino-acid peptide and was the first HIV fusion inhibitor approved for treating HIV-1 infection. It is reserved for treatment-experienced patients with evidence of viral replication despite ongoing antiretroviral therapy, typically as part of an optimized combination regimen for multidrug-resistant HIV-1. Because it must be reconstituted and injected subcutaneously twice daily, and commonly causes injection site reactions, its use has declined as newer oral antiretroviral classes have become available. It remains a prescription-only specialist therapy.

- URL: https://www.lifeconverted.com/peptides/enfuvirtide
- Also known as: Fuzeon, T-20
- Primary category: Other & Clinical
- Effectiveness rank: #20 in Other & Clinical
- Evidence level: Well studied
- Route: Subcutaneous (Reconstituted powder injected subcutaneously into the abdomen, thigh, or upper arm; rotate injection sites to reduce nodules.)
- Dose range: 45-90 mg
- Dose tiers: low 45 mg; moderate 90 mg; high 90 mg
- Half-life: Approximately 3.8 hours
- Timing: Twice daily, evenly spaced
- Cycle: Continuous twice-daily injections as part of ongoing combination antiretroviral therapy on, Not discontinued while viral suppression is needed; stopping without a fully suppressive replacement regimen risks viral rebound and resistance off (Adult dosing is fixed at 90 mg twice daily regardless of body weight above the pediatric threshold; it is not titrated upward for dose-response.)
- Storage: Store unopened vials at room temperature. After reconstitution with sterile water, refrigerate at 2-8°C and use within 24 hours; do not freeze.

## Mechanism of action

Enfuvirtide binds to the HR1 region of the HIV-1 envelope glycoprotein gp41 during the viral entry process, preventing the conformational change required for the viral and host cell membranes to fuse. By blocking this fusion step, it prevents HIV-1 from entering and infecting CD4+ T cells, acting at an earlier stage of the viral life cycle than reverse transcriptase or protease inhibitors.

## Reported benefits

- Provides an additional mechanism of action for HIV-1 resistant to other antiretroviral classes
- Can help achieve viral suppression in heavily treatment-experienced patients when combined with an optimized background regimen
- Acts extracellularly, blocking viral entry before infection of the cell occurs

## Reported side effects

- Injection site reactions (pain, redness, nodules, induration) in most patients
- Increased rate of bacterial pneumonia observed in clinical trials
- Hypersensitivity reactions, occasionally severe
- Peripheral neuropathy

## Common protocols

- Fuzeon combined with an optimized background antiretroviral regimen for multidrug-resistant HIV-1 infection

## Stacking notes

Used only in combination with other antiretroviral agents in treatment-experienced patients with resistant HIV-1; never used as monotherapy.

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