Enfuvirtide
Also known as: DP-178, Enfuvirtide, Fuzeon, T-20, T20
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Summary
Enfuvirtide is a synthetic 36‑amino‑acid peptide approved as a fusion inhibitor for the treatment of HIV‑1 infection. It is administered by subcutaneous injection, typically twice daily, and is used in combination with an optimised background antiretroviral regimen. Clinical trials in adults and children have shown that enfuvirtide reduces plasma HIV‑RNA levels and increases CD4+ T‑cell counts, particularly in patients with multidrug‑resistant virus or limited treatment options.
Mechanism of Action
Enfuvirtide binds to the gp41 subunit of the HIV‑1 envelope glycoprotein. During viral entry, gp120 attaches to CD4 and a chemokine coreceptor, triggering a conformational change in gp41 that drives fusion of viral and cellular membranes. By occupying a pocket in the gp41 ectodomain, enfuvirtide prevents the required structural rearrangement, blocking membrane merger and halting infection of the host cell.
What the Research Shows
Randomised, controlled trials in treatment‑experienced adults demonstrated that twice‑daily subcutaneous enfuvirtide (90 mg) added to an optimised background regimen reduced HIV‑RNA by roughly one log10 more than background therapy alone after 24 weeks, with the effect persisting to 48 weeks and accompanied by greater CD4+ count gains. Phase II studies in paediatric patients using weight‑adjusted doses (30–60 mg/m²) showed similar virological reductions and CD4+ increases. In vitro data confirm potent activity against multidrug‑resistant strains, and early Phase I work reported rapid viral load declines without serious adverse events. Resistance mutations in gp41 have been identified in patients receiving enfuvirtide, indicating potential for reduced susceptibility over time.
Reported Benefits
Clinical evidence indicates that enfuvirtide can achieve additional viral load suppression of about one log10 and larger CD4+ count rises when combined with an optimised regimen, offering a valuable option for patients with limited alternatives due to resistance or intolerance. Its activity against multidrug‑resistant HIV‑1 has been demonstrated both in vitro and in vivo, and efficacy has been observed in both adult and paediatric populations.
Limitations of the Evidence
Enfuvirtide must be injected subcutaneously twice daily, which can affect adherence. Resistance can emerge through mutations in the gp41 target, potentially diminishing long‑term effectiveness. The number of large, long‑term trials is limited, and most data derive from studies of 24–48 weeks duration. Comparative effectiveness versus newer entry inhibitors or long‑acting agents has not been fully established.
Safety Considerations
The most frequently reported adverse events are mild to moderate injection‑site reactions, including erythema, pain, and induration. Clinical trials noted higher rates of lymphadenopathy and pneumonia in enfuvirtide‑treated groups compared with controls, though overall serious adverse events were similar between arms. No severe systemic toxicities were identified in the reported studies, but clinicians should monitor for signs of resistance and manage injection‑site complications.
How It Is Administered
Enfuvirtide is supplied as a lyophilised powder for reconstitution and is administered by subcutaneous injection, typically 90 mg twice daily in adults. Pediatric dosing has been explored using weight‑based calculations (30–60 mg/m²). The formulation requires proper reconstitution and sterile technique; dosing frequency may be adjusted in future studies, but twice‑daily administration remains the standard based on current trial data.
Routes of Administration
Goals & Uses
- Prevention of HIV disease progressionDisease ModificationModerate
- HIV‑1 infection treatmentAntiviralHigh
- Salvage therapy for multidrug-resistant HIVAntiretroviral SalvageHigh
- Reduction of HIV-1 viral loadAntiviral / Virologic SuppressionHigh
- Increase in CD4+ T-cell countImmunological RestorationHigh
Contraindications
- Hypersensitivity to enfuvirtide or any formulation componentAllergyHigh
- Treatment-naive HIV patientsClinical IndicationModerate
- Hypersensitivity to enfuvirtide or any excipientAllergy / HypersensitivityHigh
Adverse Effects
- Peripheral neuropathyNeurologicalUncommon
- Hypersensitivity reactionsImmunologicRare
- EosinophiliaHematologicUncommon
- Injection site reactionsLocalCommon
- Fatigue and insomniaGeneral / CNSCommon
- Injection site reactions (ISRs)Local / DermatologicCommon
- Bacterial pneumoniaInfectiousUncommon
- LipodystrophyDermatologicUncommon
Drug Interactions
- RifampicinLow
- No clinically significant pharmacokinetic interactionsLow
- SaquinavirLow
- RitonavirLow
Population Constraints
- PregnancyReproductive SafetyRelative
- Renal impairmentOrgan ImpairmentRelative
- Pediatric patients <6 yearsAgeRelative
- Pediatric patients < 6 yearsAgeAbsolute
- Coagulation disorders / anticoagulant useHematologicRelative
Regulatory Status
- European UnionApprovedApproved: HIV‑1 infection in adults with resistant virusApproved by EMA (2004).
- United StatesApprovedApproved: Treatment‑experienced HIV‑1 infection in adultsApproved by FDA (2003).
- United KingdomApprovedApproved: HIV-1 infection in treatment-experienced adults and pediatric patients ≥6 years in combination with other antiretroviral agentsRetained approval post-Brexit under MHRA; consistent with EU label.
FDA approved in 2003; EMA approved 2004. Administered as twice‑daily subcutaneous injections. No oral formulation.
Evidence & Sources
- Journal ArticleModerateDando TM, Perry CM2003-01-01T00:00:00.000000Z
- Journal ArticleModerateLalezari JP, Luber AD2004-01-01T00:00:00.000000Z
- Journal ArticleModerateChen RY, Kilby JM, Saag MS2002-01-01T00:00:00.000000Z
Frequently Asked Questions
What type of HIV patients are most likely to benefit from enfuvirtide?
Enfuvirtide is primarily used for treatment‑experienced individuals whose virus is resistant to multiple other antiretrovirals, or for those who cannot tolerate standard regimens. Clinical trials have shown added viral suppression when it is combined with an optimised background regimen.
How does enfuvirtide differ from other antiretroviral classes?
Unlike reverse‑transcriptase or protease inhibitors, enfuvirtide targets the entry step of the viral life cycle. It binds to the gp41 fusion protein, preventing the conformational change needed for the virus to merge with the host cell membrane.
Are there any serious side effects associated with enfuvirtide?
The most common adverse effects are injection‑site reactions, which are usually mild to moderate. Some trials reported higher incidences of lymphadenopathy and pneumonia, but serious systemic toxicities have not been prominent in the published studies.
Can enfuvirtide be used as a once‑daily injection?
Current evidence supports twice‑daily subcutaneous dosing. Pharmacokinetic data suggest once‑daily dosing is a theoretical possibility, but it has not been validated in clinical trials to date.
What is Enfuvirtide?
Enfuvirtide is a synthetic 36‑amino‑acid peptide approved as a fusion inhibitor for the treatment of HIV‑1 infection. It is administered by subcutaneous injection, typically twice daily, and is used in combination with an optimised background antiretroviral regimen. Clinical trials in adults and children have shown that enfuvirtide reduces plasma HIV‑RNA levels and increases CD4+ T‑cell counts, particularly in patients with multidrug‑resistant virus or limited treatment options.
What is Enfuvirtide used for?
Enfuvirtide is educationally associated with: Prevention of HIV disease progression, HIV‑1 infection treatment, Salvage therapy for multidrug-resistant HIV, Reduction of HIV-1 viral load, Increase in CD4+ T-cell count. Educational only — not medical advice.
How is Enfuvirtide administered?
Recorded routes of administration: Subcutaneous.
What are the potential side effects of Enfuvirtide?
Reported adverse effects include: Peripheral neuropathy, Hypersensitivity reactions, Eosinophilia, Injection site reactions, Fatigue and insomnia, Injection site reactions (ISRs), Bacterial pneumonia, Lipodystrophy. This list is not exhaustive — consult a qualified clinician.
Who should avoid Enfuvirtide?
Recorded contraindications: Hypersensitivity to enfuvirtide or any formulation component, Treatment-naive HIV patients, Hypersensitivity to enfuvirtide or any excipient. Consult a qualified clinician before use.