Fact Sheet Number 451
- WHAT IS ENFUVIRTIDE?
- WHO SHOULD TAKE IT?
- WHAT ABOUT DRUG RESISTANCE?
- HOW IS ENFUVIRTIDE TAKEN?
- WHAT ARE THE SIDE EFFECTS?
- HOW DOES IT REACT WITH OTHER DRUGS?
- THE BOTTOM LINE
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PrintEnfuvirtide, also called Fuzeon® or T-20, is a drug used for
antiviral therapy. It is manufactured by Roche and Trimeris. Enfuvirtide
has not been approved by the FDA for use against HIV. It is available
through an expanded access program.
Enfuvirtide is the first “fusion inhibitor” drug.
When HIV infects a cell, it attaches to the outside of the cell.
Then it “fuses” or joins itself with the cell. Enfuvirtide
stops this process of fusion. This means that HIV cannot infect
that cell.
IT?
There are no absolute rules about when to start antiviral drugs.
You and your doctor should consider your T-cell
count, your viral load,
any symptoms you are having, and your attitude about taking HIV
medications. Fact Sheet 411
has more information about guidelines
for the use of antiviral medications.
Enfuvirtide is injected twice a day. It will most likely be
used by people who have run out of choices to use antiviral medications
in pill form.
If you take enfuvirtide with other antiviral drugs, you can
reduce your viral load and increase your T-cell counts. This should
mean staying healthier longer.
RESISTANCE?
The HIV virus is sloppy when it makes copies of its genetic code
(RNA). Many new copies of HIV are mutations: they are slightly
different from the original virus. Some mutations can continue
to multiply even when you are taking an antiviral drug. When this
happens, the drug will stop working. This is called “developing
resistance” to the drug. See Fact
Sheet 414 for more information on resistance.
Resistance to enfuvirtide can develop quickly if it is taken
by itself. With combination therapy (taking more than one antiviral
drug at the same time), HIV mutates much more slowly. Resistance
takes longer to develop. It is very important to take antiviral
medications according to instructions, on schedule, and not to
skip or reduce doses.
Sometimes, if you develop resistance to one drug, you will
also have resistance to other antiviral drugs. This is called
“cross-resistance”. Enfuvirtide does not have cross
resistance with any other antiviral drugs.
TAKEN?
If enfuvirtide is swallowed, it is destroyed by stomach acids.
This means that it cannot be taken in pill form. Enfuvirtide is
injected just under the skin. This is called a “subcutaneous”
injection.
The adult dosage of enfuvirtide is 90 mg per injection, twice
a day. The dosage for children is based on their body weight.
If your doctor prescribes enfuvirtide, you will shown how to
prepare each injection, and how and where to inject it.
Enfuvirtide is a new class of antiviral drug. This means that
it is active against HIV that has developed resistance to any
other antiviral drug. However, it cannot be used by itself. It
must be combined with other antiviral drugs.
WHAT ARE THE SIDE EFFECTS?
The most common side effects of enfuvirtide are skin reactions
where the drug is injected. Almost everybody who uses enfuvirtide
gets these reactions. They can be very mild, such as slight redness.
They can include itching, swelling, pain, hardened skin, or hard
lumps. Each reaction might last up to a week. With two injections
each day, people using enfuvirtide might have reactions at several
spots on their body at the same time. Very few patients have stopped
using it because of skin reactions.
The most common other side effects of enfuvirtide are headache,
pain and numbness in feet or legs, dizziness, and loss of sleep.
WITH OTHER DRUGS?
Enfuvirtide has been studied to see if it interacts with other
drugs. There are no known interactions with other anti-HIV medications.
However, it has not been studied with all medicines, over-the-counter
drugs or vitamin or herbal supplements. Be sure your doctor knows
about all medications and supplements that you are taking.
THE BOTTOM LINE
Enfuvirtide is the first drug in a new class. It stops HIV
from “fusing” with a cell it has attached to. This prevents
HIV from infecting the cell. Enfuvirtide has not yet been approved
by the Food and Drug Administration, but it is available through
an expanded access program. Enfuvirtide helps control HIV, even
when it is resistant to other medications.
Enfuvirtide has to be injected under the skin twice daily.
Almost everyone who uses it gets skin reactions where it is injected.
Most of these are not serious.
Revised November 24, 2002
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New Mexico AIDS Education and Training Center
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