INTRODUCTION — Protease inhibitors are antiretroviral medications that commonly used in the treatment of HIV. Proteases are enzymes that the virus requires to copy itself. Thus, protease inhibitors can prevent or limit the virus's ability to copy itself. When proteases are blocked, HIV makes copies of itself that cannot infect new cells. This can reduce the amount of virus in the blood and increase the number of CD4 cells.
Protease inhibitors are generally combined with at least two other anti-HIV medications; this combination is called highly active antiretroviral therapy (HAART). The combination treatment reduces the risk of the virus becoming resistant to treatment.
IMPORTANT GENERAL ADVICE — To help assure that the protease inhibitor keeps working and to avoid drug interactions and resistance, keep the following in mind: Take protease inhibitors consistently, uninterrupted, along with your other antiretroviral medicines for HIV. Take the prescribed dosage and correct number of capsules per day. Review this with your health care provider at each visit. Protease inhibitors can interact with many other medicines. Report any other medications you are taking or have stopped taking to your clinician and pharmacist. This includes nonprescription drugs and herbal medicines from health food stores.
For example, garlic supplements and St. John's wort substantially reduce concentrations of the some protease inhibitors. Ask your pharmacist or clinician to check if there are any interactions between your protease inhibitor and any other medications or herbal medications you are taking. Call your healthcare provider's office immediately if you have difficulty getting any of your antiretroviral prescriptions filled. It is important to take all of the medications in your combination regimen each and every day. Taking only a portion of the combination of HIV medications can lead to resistance. When resistance occurs, that drug is no longer effective against HIV. Check with the pharmacist and your healthcare provider's office immediately if the medicines you get from your pharmacy look different from how they looked before, or if it seems that the dosage is different from what you recall. When you need refills, call your pharmacy several days in advance to make sure they have your HIV medicines in stock. Consider using a pharmacy that specializes in HIV medicines and/or one that will call you each month to see if you need refills. If you have to go to the hospital, it is helpful to bring a list of your medications, or even the medications themselves to be certain that there is no interruption in your dosing. You should give the medications to your physician, and not take them on your own, once you are in the hospital. If you are taking ritonavir (Norvir®) or tipranavir (Aptivus®), take only a one day supply since these medications need to be kept cool. Never change the number of pills you are taking without speaking with your clinician. Never stop any of your antiretroviral HIV medicines without checking with your clinician. It is generally better to use one pharmacy for all of your medication needs. If you have to use more than one pharmacy, make sure each pharmacy is aware of all of the medications you are taking.
ADVICE ON SPECIFIC PROTEASE INHIBITORS — The following information will serve as a guide on how best to take the particular protease inhibitor medication that you have been prescribed.
Atazanavir (Reyataz®) — Take with food. Certain medications, called proton pump inhibitors, have an effect on stomach acid and interact badly with atazanavir. For this reason, it is important not to take omeprazole (Prilosec®), esomeprozole (Nexium®), or lansoprazole (Prevacid®) while you are taking atazanavir because the atazanavir may not work. Talk to your health care provider and pharmacist before you take other medicines that decrease acid in your stomach like calcium (Tums®), ranitidine (Zantac®), or cimetidine (Tagamet®); these should be taken at a different time of the day than the atazanavir.
Fosamprenavir (Lexiva®) — Take with or without food. Tell your health care provider if you are allergic to sulfonamide medicines.
Indinavir (Crixivan®) — Take with plenty of water (at least 48 ounces or 1.5 liters per day) to decrease the risk of developing kidney stones. Store indinavir (Crixivan®) in a dry place.
The way you need to take indinavir will depend on whether or not to you are taking ritonavir (Norvir®) also. Take indinavir (Crixivan®) on an empty stomach (one hour before a meal or two hours after a meal) or with a low-fat snack. Check with your pharmacist or physician for a list of acceptable low fat snacks. If you are also taking ritonavir (Norvir®), you do not have to take the indinavir on an empty stomach.
Lopinavir/ritonavir (Kaletra®) — Take with food.
Nelfinavir (Viracept®) — Take with food. Call your health care provider right away if you develop diarrhea, which is a common side effect.
Ritonavir (Norvir®) — Take with meals. Store in the refrigerator or at room temperature (less than 77) for 30 days or less.
Saquinavir (Invirase®) — Take with meals or within two hours of a meal. If you are currently taking Invirase in the 200 mg strength, ask your health care provider about the invirase 500 mg tablets.
Tipranavir (Aptivus) — Take tipranavir (Aptivus 500 mg) with ritonavir (Norvir 200 mg) twice daily with meals. There are several drug interactions between tipranavir and drugs from six classes of medications as well as St John's wort. You should discuss your full medication list, including herbal medications, with your physician or pharmacist before initiating tipranavir.
Darunavir (Prezista®, TMC 114) — Take darunavir (Prezista®) with ritonavir (Norvir®) twice a day with food. Tell your healthcare provider if you are allergic to sulfonamide (sulfa) medications.
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.
This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.
A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. Centers for Disease Control and Prevention (CDC)
Toll-free: (800) 311-3435
(www.cdc.gov)
CDC (Centers for Disease Control and Prevention) National AIDS Hotline
English: (800) 342-2437
Spanish: (800) 344-7432
National Institute of Allergy and Infectious Diseases (NIAID)
(www.niaid.nih.gov)
HIV/AIDS Treatment Information Service
Toll-free: (800) 448-0440
(www.hivatis.org)
AIDS Clinical Trials Information Service (ACTIS)
Toll-free: (800) 874-2572
(www.actis.org)
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Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Piscitelli, SC, Burstein, AH, Welden, N, et al. The effect of garlic supplements on the pharmacokinetics of saquinavir. Clin Infect Dis 2002; 34:234.
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