Enfuvirtide (Fuzeon)_Dosage, benefits & legal status
Also known as Fuzeon, T-20, DP-178, pentafuside
A pioneering anti-HIV peptide that stops the virus fusing with cells, now discontinued in the US.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Enfuvirtide (Fuzeon)?
Plain language first. The technical label stays, but it never stands alone.Overview
It latches onto the part of gp41 the virus folds up to pull its membrane into a cell, so the virus cannot get in. It helped people whose HIV resisted every other drug class, but needed two injections a day that almost always caused skin reactions. Newer drugs replaced it, and Genentech stopped US distribution on 28 February 2025.
Enfuvirtide (T-20) is a 36-residue synthetic peptide copied from part of HIV's own gp41 fusion protein. Duke researchers found the parent peptide DP-178, Trimeris developed it with Roche, and the FDA approved it as Fuzeon in March 2003.
What it's used for
An HIV fusion inhibitor for treatment-experienced patients, injected twice daily. No longer sold in the US.
How does Enfuvirtide (Fuzeon) work?
What it does in the body, and where.Enfuvirtide copies a 36-residue stretch of HIV's gp41 protein (residues 643 to 678 in the original isolate).
- 01Binding HR1It binds the first heptad-repeat region (HR1) of gp41, the protein HIV uses to fuse its membrane with a cell's.
- 02Fusion stallsWith enfuvirtide bound, gp41 cannot make the shape change needed to pull the two membranes together, so the virus stays outside the cell.
- 03ResistanceChanges at gp41 positions 36 to 38, such as G36D or V38A, let the virus escape. It is specific to HIV-1.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
TORO trials
FDA-approved- Human trialTORO 1, 501 people in the Americas: viral load fell 1.70 log against 0.76 at 24 weeks.
- Human trialTORO 2, Europe and Australia: 1.43 log against 0.65.
- No data48-week response rates differ between the label (46%) and the published pooled analysis (37.4%) for a 1 log drop; name the source.
The October 2004 action is often called full or traditional approval; the FDA letter says it fulfilled the accelerated-approval commitments. The '90 mg vial' holds 108 mg so that 90 mg can be drawn. It binds the HR1 region of gp41, not gp41 in general. It was not withdrawn for safety reasons; Genentech and Roche cite reduced need. Response rates differ between the label and the 48-week papers, so name the source. T-20 as a search term collides with time-point labels in unrelated papers.
The published record
Papers and trials about Enfuvirtide (Fuzeon)
423 papers tagged human · 207 not reviews or lab · 29 clinical trial publications
54 registered trials · 15 with posted results
Furthest stage reached: Approved in the US, no longer sold
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count. 475 papers and 54 trials indexed in detail.
At a glance
Four things to know about Enfuvirtide (Fuzeon)
Evidence
FDA-approved
Category
Immune support
Common vial
Varies
Half-life
About 3.8 hours
How much, and do you cycle it?
The range, and whether you take breaks.90 mg twice daily (label), twice daily. Continuous, twice daily FDA label
Taken twice daily without breaks as part of a combination regimen, like all HIV treatment.
About 3.8 hoursFDA label
3.8 +/- 0.6 hours after a single 90 mg dose under the skin; bioavailability about 84%; about 92% bound to plasma proteins. Broken down to its amino acids.
Source: Fuzeon prescribing information section 12.3
You can compare this against the whole library to see where it sits.
How do I dose and price it?
Enter your vial and your dose. Pick a mix. We show the draw and the cost.The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.
Choose your mix
Measuring the water1 mL = one full 100-unit syringe.
How do you store it?
Before mixing, and after.Dry powder in the freezer or fridge. Once mixed, fridge, and use within about a month.
Unmixed lyophilized Enfuvirtide (Fuzeon) keeps for a long time cold. Once you add water the clock starts: most reconstituted vials hold up for roughly 28 to 30 days at fridge temperature. Keep it out of light, and do not freeze it after mixing.
What are the side effects and cautions?
Known cautions and warnings for this compound.Solubility, computed: 31% charged residues, 36% hydrophobic. Water usually sufficient.
A first-pass rule from peptide manufacturers' guidance. It does not account for disulfide bridges, salt form or how the powder was dried, and it predicts what should be easy rather than what will happen in your vial.
Who should avoid it
- Known allergy to enfuvirtide or any ingredient
- Bleeding disorders or blood thinners, because of the risk of bleeding after injection
- Breastfeeding
- Use in people without HIV: antibodies against it can make an HIV test read falsely positive
Stop and get help
- Rash with fever, nausea, chills or low blood pressure, a possible hypersensitivity reaction; do not restart
- Cough with fever or breathlessness, given the higher pneumonia rate
- A hot, painful, spreading injection site, a possible abscess or cellulitis
Common effects
- Injection-site reactions in 98%: pain 96%, redness 91%, hardening 90%, nodules or cysts 80%
- Diarrhoea, nausea and tiredness, at lower rates per patient-year than in the control arm
- Pneumonia at 6.7 events per 100 patient-years against 0.6
- 4% stopped because of injection-site reactions
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Enfuvirtide (Fuzeon) approved?
And where the numbers on this page come from.Approved, but no longer sold in the United States. Enfuvirtide (Fuzeon) was approved by the FDA, and the US product has since been discontinued. It is also approved in the European Union.
- Approval statusFDA-approved
- RouteUnder the skin (subcutaneous)
- Checked12 October 2026
- Approved outside the USEuropean Union: Authorised in the EU on 27 May 2003 (Roche). The EMA page still listed it as authorised at its February 2024 update, but supply has ended in France (September 2025) and the UK.This does not change the United States position above.
- DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesFuzeon prescribing information (revised 8/2019)Drugs@FDA, NDA 021481FDA accelerated approval letter (13 Mar 2003)Genentech statement on Fuzeon (19 Aug 2024)Lalezari JP et al., New England Journal of Medicine 2003;348:2175-2185 (TORO 1)Lazzarin A et al., New England Journal of Medicine 2003;348:2186-2195 (TORO 2)Wild CT et al., PNAS 1994;91:9770-9774EMA, Fuzeon EPARFDA GSRS substance record, enfuvirtide (UNII 19OWO1T3ZE)
What has happened recently
FDA accelerated approval on 13 March 2003 (NDA 021481), the first HIV fusion inhibitor; a supplement approved on 15 October 2004 fulfilled the accelerated-approval commitments. Genentech ended US marketing and distribution on 28 February 2025, citing reduced need given newer options and not safety or efficacy; Drugs@FDA lists it as discontinued. The EU authorised Fuzeon on 27 May 2003; Roche stopped supplying it in France from 30 September 2025, and the UK lists it as discontinued.
You can compare this against the whole library, or read how to check a seller.
What else is like Enfuvirtide (Fuzeon)?
Others in Immune support, side by side.If you're weighing Enfuvirtide (Fuzeon), it's worth reading Icatibant (Firazyr), Imunofan, and Mifamurtide (Mepact) in the same class.
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- Dose
- 90 mg twice daily (label)
- How often
- Twice daily
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- Dose
- 2 mg/m2 per infusion (EU label)
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Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Sources
- Fuzeon prescribing information (revised 8/2019)(2019)90 mg SC twice daily; Ac-36-mer-NH2, C204H301N51O64, MW 4492. Binds HR1 of gp41. Injection-site reactions 98%. Half-life 3.8 hours. Pooled 48 weeks: at least a 1 log drop in 46% against 18%.
- Drugs@FDA, NDA 021481(2025)Approved 13 March 2003, new molecular entity, priority review; now listed as discontinued.
- FDA accelerated approval letter (13 Mar 2003)(2003)Approved under the accelerated approval regulations, with 48-week data required by the end of 2003.
- Genentech statement on Fuzeon (19 Aug 2024)(2024)US marketing and distribution to end on 28 February 2025 because of evolving practice and reduced need; not related to quality, safety or efficacy.
- Lalezari JP et al., New England Journal of Medicine 2003;348:2175-2185 (TORO 1)(2003)501 randomised in the Americas: 24-week viral load fell 1.70 against 0.76 log10 (P<0.001); CD4 +76 against +32.
- Lazzarin A et al., New England Journal of Medicine 2003;348:2186-2195 (TORO 2)(2003)Europe and Australia: 24-week viral load fell 1.43 against 0.65 log10 (P<0.001).
- Wild CT et al., PNAS 1994;91:9770-9774(1994)DP-178 from gp41 blocked HIV-1 cell fusion at under 5 ng/mL (IC90 about 1.5 ng/mL).
- EMA, Fuzeon EPAR(2024)Authorised 27 May 2003, holder Roche Registration; listed as authorised at the February 2024 update.
- FDA GSRS substance record, enfuvirtide (UNII 19OWO1T3ZE)(2026)36-residue sequence with N-acetyl tyrosine and C-terminal phenylalanine amide; CAS 159519-65-0.
Beyond these, 529 records are indexed. Browse the records