SAQUINAVIR (Fortovase, Invirase)
- WHAT IS SAQUINAVIR?
- WHO SHOULD TAKE IT?
- WHAT ABOUT DRUG RESISTANCE?
- HOW IS IT TAKEN?
- WHAT ARE THE SIDE EFFECTS?
- HOW DOES IT REACT WITH OTHER DRUGS?
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Saquinavir is a drug used for antiviral therapy. There are
two versions: Invirase® and Fortovase®. It is manufactured
by Roche Laboratories.
Saquinavir 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.
The first version was Invirase. It worked well for some people,
but it is not absorbed very well. Fortovase is the newer version.
It is absorbed much better, so more of the drug gets into the
bloodstream.
IT?
Saquinavir 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 saquinavir 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”.
Resistance can develop quickly. It is very important to
take antiviral medications according to instructions, on schedule,
and not to skip or reduce doses.
The normal dose of the Saquinavir soft-gel capsule (Fortovase®)
is 1,200 milligrams (mg) three times a day. The capsules are 200mg,
so you will take 6 capsules three times a day. Researchers are
studying twice a day dosing of saquinavir.
Some physicians prescribe saquinavir in combination with another
protease inhibitor, ritonavir. The older formulation of saquinavir,
Invirase, seems to work better in combinations with ritonavir.
Studies are underway using a single daily dose of saquinavir taken
with a small amount of ritonavir.
Saquinavir should be taken within two hours after a full meal
or a large snack. It is absorbed better if you take it after eating
foods that are high in calories, fat, and protein.
Your pharmacist should keep saquinavir refrigerated. When you
take it home, you can refrigerate it, or else keep it below 77º
F (25º C) and use it within three months.
WHAT
ARE THE SIDE EFFECTS?
The side effects of saquinavir are usually mild. Most people
can take it with no problems. However, some people get nausea,
diarrhea, upset stomach, and heartburn.
HOW DOES SAQUINAVIR REACT WITH OTHER DRUGS?
Saquinavir 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 several
antihistamines, sedatives, and anti-fungal drugs. Make sure that
your doctor knows about ALL drugs you are taking.
Some birth control pills may not work if you are taking saquinavir.
Talk to your doctor about how to prevent an unwanted pregnancy.
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 March 25,
2002
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New Mexico AIDS Education and Training Center
and the New Mexico Department of Health