Protease Inhibitors (PIs) for HIV
Some of these medicines must be used with ritonavir.
How It Works
Protease inhibitors (PIs) are antiretroviral medicines. They prevent HIV from multiplying, reducing the amount of virus in your body. When the amount of virus in the blood is kept at a minimum, the immune system has a chance to recover and grow stronger.
Why It Is Used
The use of three or more antiretroviral medicines (highly active antiretroviral therapy, or HAART) is the usual treatment for HIV infection.
The combination of medicines used for HAART will depend on your health, other conditions you might have (such as hepatitis), and results of testing. Talk to your doctor about the best treatment plan for you.
You may also want to start HIV treatment if your sexual partner does not have HIV. Treatment of your HIV infection can help prevent the spread of HIV to your sexual partner.3
The U.S. National Institutes of Health recommend one of the following programs for people who begin treatment for HIV:1
How Well It Works
Antiretroviral therapy can also decrease symptoms of HIV infection, such as fever and weakness, and help the person gain weight.
The rate at which antiretrovirals decrease viral loads is affected by:1
To prevent serious medicine interactions or a decrease in medicine effectiveness, be sure to learn which medicines should not be taken with PIs and other antiretroviral medicines.
PIs may cause:
Indinavir causes kidney stones in 5% of people who use it. The risk of kidney stones can be reduced by drinking at least 48 fl oz (1.4 L) of fluid each day.
Certain protease inhibitors (fosamprenavir, indinavir, and lopinavir/ritonavir) have been associated with a small increase in the risk of having a heart attack.
Side effects of any combination medicine can include the side effects of any of the single medicines in the combination.
Report all side effects to your doctor at your next visit. He or she can adjust your dose or give you other medicines to reduce side effects. Some mild side effects, such as nausea, improve as your body adjusts to the medicine.
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
Many people think antiretroviral medicines always have severe side effects. In fact, only a few people experience severe or dangerous side effects.
Food increases the absorption of atazanavir, nelfinavir, and darunavir.4 Certain acid-reducing medicines, such as omeprazole or famotidine, should not be taken at the same time as atazanavir. Before you take protease inhibitors (PIs), be sure to tell your doctor about any other medicines you are taking.
Resistance to PIs develops more frequently if these medicines are used alone or are not taken exactly as prescribed.
Lopinavir is combined with a low dose of ritonavir to inhibit the breakdown of lopinavir in the body. This delayed breakdown of lopinavir increases its effectiveness.
PIs are expensive. They can cost up to two times more than nucleoside/nucleotide reverse transcriptase inhibitors (NNRTIs).
Things to think about when choosing a combination of medicines include:
Do not use the nonprescription herbal supplement St. John's wort while you are taking a protease inhibitor, because St. John's wort can interfere with how well these medicines work.
Talk to your doctor about whether you can eat grapefruit or drink grapefruit juice while you are taking protease inhibitors. It may increase the side effects of some of these medicines.5
eMedicineHealth Medical Reference from Healthwise
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