Fact Sheet Number 445
- WHAT IS AMPRENAVIR?
- WHO SHOULD TAKE IT?
- WHAT ABOUT DRUG RESISTANCE?
- HOW IS IT TAKEN?
- VITAMIN E
- WHAT ARE THE SIDE EFFECTS?
- HOW DOES IT REACT WITH OTHER DRUGS?
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PrintAmprenavir is a drug used for antiviral therapy. It is also called
Agenerase®. It is manufactured by GlaxoSmithKline. It used
to be called 141W94.
Amprenavir is a protease inhibitor. These drugs prevent the protease
enzyme from working. HIV protease acts like a chemical scissors.
It cuts the raw material for HIV into specific pieces needed to
build a new virus. Protease inhibitors “gum up” these
scissors.
WHO
SHOULD TAKE IT?
Amprenavir was approved as an antiviral drug for people with HIV
infection. 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.
If you take amprenavir with other antiviral drugs, you can
reduce your viral load to extremely low levels, and increase your
T-cell counts. This should mean staying healthier longer.
RESISTANCE?
Many new copies of HIV are mutations. They are slightly different
from the original virus. Some mutations can keep multiplying 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.
Sometimes, if your virus develops resistance to one drug, it
will also have resistance to other antiviral drugs. This is called
“cross-resistance”. Researchers are excited about Amprenavir
because it might not be cross-resistant with other protease inhibitors.
Resistance can develop quickly. It is very important to
take antiviral medications according to instructions, on schedule,
and not to skip or reduce doses.
Amprenavir is taken by mouth as a capsule. The normal adult dose
is 1200 milligrams (mg) two times a day. The capsules are 150mg,
so you will take 8 capsules at a time. The dose is lower, based
on body weight, for children and people who weigh less than 50
kilograms (110 pounds).
Amprenavir was also approved in two combinations with the protease
inhibitor ritonavir:
- 600 mg (4 capsules) of amprenavir plus 100 mg (one capsule)
of ritonavir, taken twice a day, or
- 1200 mg (8 capsules) of amprenavir plus 200 mg (2 capsules)
of ritonavir, taken just once a day.
Different doses are used in some combinations. Be sure you
know how much amprenavir your doctor has prescribed for you, and
when and how to take each dose.
If you have liver problems, you may need to take a lower dose
of amprenavir.
Amprenavir is available as gelatin capsules and as a liquid.
The gelatin capsules should be kept at room temperature. If they
get too warm, they can melt. People taking the liquid form should
not drink alcoholic beverages.
It can be taken with or without food, but high-fat meals should
be avoided. Do not take antacids within one hour of taking
amprenavir.
GlaxoSmithKline is developing GW433908, a new form of amprenavir.
It is a “prodrug.” A prodrug becomes active after it
is broken down in the body. GW433908 should provide the same benefits
with fewer pills.
Amprenavir capsules contain vitamin E. The Vitamin E improves
how the drug is absorbed and how it works. Each 150mg capsule
contains 109 International Units (IU) of Vitamin E. The normal
adult dose contains 1,744 IU of vitamin E. This information can
help you decide what vitamin supplements to take.
EFFECTS?
The most common side effects are nausea, diarrhea, vomiting, rash,
numbness around the mouth, and abdominal pain. About 1% of people
get serious skin reactions, including Stevens-Johnson syndrome.
No other side effects seem to be very serious. The diarrhea in
most cases can be controlled with over-the-counter medications.
Amprenavir might not cause problems with high cholesterol levels
the way that other protease inhibitors do.
Amprenavir is a sulfa drug. If you are allergic to sulfa drugs,
be sure to tell your doctor.
Liquid amprenavir contains an ingredient called propylene glycol.
It can cause problems, and should not be used by the following
patients:
- infants or children under 4 years old
- pregnant women
- people with liver or kidney failure
- people taking certain medications (check with your doctor.)
WITH OTHER DRUGS?
Amprenavir is broken down by the liver and can interact with other
drugs that also use the liver. Combining these drugs can change
the amount of each drug in your bloodstream and cause an under-
or overdose. Drugs to watch out for include Viagra, several antihistamines,
sedatives, drugs to lower cholesterol and anti-fungal drugs. Make
sure that your doctor knows about ALL drugs you are taking.
Amprenavir works better if it is taken with the reverse
transcriptase inhibitor abacavir.
If you are taking amprenavir and ddI,
you should take them one hour apart. You should also take amprenavir
one hour apart from antacids.
Some birth control pills may not work if you are taking amprenavir.
Talk to your doctor about how to prevent an unwanted pregnancy.
Taking amprenavir with methadone can lower blood levels of
both drugs. Check with your doctor if you use methadone.
The herb St. John’s Wort (See
Fact Sheet 729) lowers the blood levels of some protease inhibitors.
Tell your doctor about any herbs or other supplements that you
use.
Revised August 16, 2002
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New Mexico AIDS Education and Training Center
and the New Mexico Department of Health