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Will I Need Other Medications?

December 1997

If you take saquinavir (Invirase or Fortovase) you will also need to take one or two other antiviral medications, called reverse transcriptase inhibitors. Reverse transcriptase inhibitors such as AZT (Retrovir), ddI (Videx), ddC (Hivid), d4T (Zerit), or 3TC (Epivir) are antiviral drugs that block HIV at a different point in its life cycle than protease inhibitors (see diagram).

Although indinavir (Crixivan), ritonavir (Norvir), and nelfinavir (Viracept) may be taken by themselves, most doctors will also prescribe one or two reverse transcriptase inhibitors along with the protease inhibitor. Research shows that combining two or more antiviral drugs is more effective than taking one drug alone. The HIV/AIDS Treatment Information Service can give you information on all of these anti-HIV drugs.

How often will I take my protease inhibitor? For how long?

Each of the approved protease inhibitors is taken in a different way. You may take your protease inhibitor two or three times every day, depending on which one you take. It is important to take the protease inhibitor on schedule so the drug will stay at the same level in your body. Taking a "drug holiday" or skipping doses is dangerous. Missing one or more doses can allow the virus to become resistant, meaning the virus changes itself to avoid the medication and keep making copies of itself.


You should take the protease inhibitor for as long as your tests show it is helpful; your doctor will keep track of your progress based on blood tests that you will have on a regular basis. (see How will I know if my protease inhibitor is working?)

How will I take my protease inhibitor?

You will take the protease inhibitor orally (by mouth). Whichever protease inhibitor you take, it is important to set a medication routine and stick to it. Some medications work best if taken on an empty stomach, while others must be taken with food, or with a large amount of water. Your doctor or pharmacist should give you specific instructions for taking your medication. The chart below has information about dosage and special instructions for each of the approved protease inhibitors.

Protease Inhibitor Dosage Information Special Instructions
nelfinavir (Viracept) (1,2,3) 3 tablets, 3 times a day (9 total tablets each day) Take with a meal or a snack. Keep at room temperature.
saquinavir (Fortovase) (4) 6 capsules, 3 times a day (18 total capsules each day) Take within 2 hours of a full meal. Keep refrigerated until the expiration date printed on the label. If capsules reach room temperature, they should be used within 3 months.
saquinavir (Invirase) (4) 3 capsules, 3 times a day (9 total capsules each day) Take within 2 hours of a full meal. Keep at room temperature.
indinavir (Crixivan) 2 capsules, 3 times a day (6 total capsules each day) Take on an empty stomach 1 hour before or 2 hours after a meal. Drink at least 1½ liters of liquid every day. Keep at room temperature in original bottle.
ritonavir (Norvir) (1,2,3)

6 capsules, 2 times a day (12 total capsules each day)


7.5 mL liquid Norvir, 2 times a day

Take with meals. Keep refrigerated.

1) Phenylketonurics: Viracept oral powder contains 11.2 mg phenylalanine per gram.

2) Persons with hemophilia should be monitored for increased bleeding.

3) Interferes with effectiveness of birth control pills; a different method or backup should be used.

4) The two forms of saquinavir (Invirase and Fortovase) require different doses and handling. Please refer to the appropriate instructions for each drug.

Nelfinavir (Viracept) Dosage Information For Children
Body Weight Dosage
15.5 lb to <18.5 lb 4 scoops or 1 teaspoon
18.5 lb to <23 lb 5 scoops or 1 ¼ teaspoons
23 lb to <26.5 lb 6 scoops or 1 ½ teaspoons
26.5 lb to <31 lb 7 scoops or 1 ¾ teaspoons
31 lb to <35 lb 8 scoops or 2 teaspoons
35 lb to <39.5 lb 9 scoops or 2 ¼ teaspoons
39.5 lb to <50.5 lb 10 scoops or 2 ½ teaspoons
50.5 lb+ 15 scoops or 3 ¾ teaspoons
Ritonavir (Norvir) Dosage Information For Children
Body Surface Area Liquid Dosage
0.25 m(sq) 1.25 mL
0.50 m(sq) 2.5 mL
1.00 m(sq) 5 mL
1.25 m(sq) 6.25 mL
1.50 m(sq) 7.5 mL

Remember that you may be taking other antiviral drugs with the protease inhibitor. Planning when to take several different medications can be tricky, so review the instructions carefully and ask for some help from your doctor or pharmacist if you have trouble staying on schedule.

Are there medications I should not take with protease inhibitors?

Some drugs can cause problems (interactions) when they are taken together. Interactions might make your drugs less effective, or they could make you sick. Even some of the drugs that you might be taking to treat an infection or to keep you from getting an opportunistic illness (prophylaxis) should not be taken with a protease inhibitor. Your doctor may say that taking those drugs together is contraindicated. For example, rifamycin drugs (rifampin and rifabutin) which are used to treat TB (tuberculosis) or MAC (Mycobacterium avium complex) can interact with protease inhibitors. In this interaction, the rifamycin makes the protease inhibitor less effective, and the protease inhibitor increases the chances of rifamycin side effects.

If you have HIV and you also have either TB or MAC, you should talk to you doctor about these options:

  • stopping the protease inhibitor during treatment including rifampin and other anti-TB/anti-MAC drugs;

  • stopping the protease inhibitor during treatment including rifampin and other anti-TB/anti-MAC drugs, then stopping the rifampin, but continuing the other anti-TB/anti-MAC drugs and the protease inhibitor;

  • taking the anti-TB/anti-MAC treatment with rifabutin instead of rifampin (only if the protease inhibitor is indinavir (Crixivan));

  • taking one-half the usual dose of rifabutin (only if the protease inhibitor is nelfinavir (Viracept).

Also, if you have not yet started a protease inhibitor, the recommendation is to finish treatment with rifampin and other anti-TB/anti-MAC drugs before starting the protease inhibitor.

Check the table, Medications That Should Not Be Used With, to make sure you are not taking drugs together that are contraindicated. Be sure to talk to your doctor before stopping or starting any drug.

Usually, your doctor can prescribe a different drug that will help you avoid an illness or treat a symptom.

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This article was provided by AIDSinfo. It is a part of the publication HIV Protease Inhibitors and You. Visit the AIDSinfo website to find out more about their activities and publications.