- What are protease inhibitors in antiretroviral therapy for HIV infection?
- What is antiretroviral therapy for HIV infection?
- What is HIV infection?
- How do protease inhibitors work in antiretroviral therapy for HIV infection?
- What are the major side effects of protease inhibitors?
- What are the FDA-approved protease inhibitors and their side effects?
What are protease inhibitors in antiretroviral therapy for HIV infection?
Protease inhibitors are one of the classes of drugs in the combination of drugs used for antiretroviral therapy (ART) for human immunodeficiency virus (HIV) infection. Protease inhibitors were first introduced in 1995 and are effective for both HIV-1 and HIV-2 infections.
Nucleoside reverse transcriptase inhibitors (NRTIs) form the backbone of the three-drug ART regimen, and protease inhibitors are often an additional drug class included in the regimen, to improve the chances of controlling the viral growth.
What is antiretroviral therapy for HIV infection?
Antiretroviral therapy is a combination treatment regimen for HIV infection, with different classes of drugs that work in different ways. Each ART regimen is tailored to suit individual conditions and requirements. There is no cure for HIV infection, but ART can effectively manage HIV as a chronic disease.
Protease inhibitors have a low incidence of drug resistance in treatment-naive patients (patients undergoing treatment for the first time). Drug resistance tests are performed before ART is initiated, but protease inhibitor-based ART regimens are often started as first-line treatment for acute HIV infection while test results are awaited.
What is HIV infection?
HIV infection is caused by a virus that attacks the human immune system. HIV targets and enters an immune cell known as T-cell, and uses its cell machinery to create more HIV viral copies, which disperse to infect other T-cells.
Uncontrolled HIV infection in its later stages results in acquired immune deficiency syndrome (AIDS), when the immune system becomes highly impaired and loses its ability to fight infections effectively.
How do protease inhibitors work in antiretroviral therapy for HIV infection?
Once the HIV enters and integrates its genome with the host cell’s DNA, it makes long chains of HIV proteins. At this stage the virus is immature and noninfectious to other T-cells. The viral DNA then releases an enzyme known as protease, which is essential in breaking up the protein chains to make new functional virus particles.
Protease inhibitors bind to the protease enzyme and inhibit its activity, and prevent the break-up of the protein chains. Formation of new infectious virus particles is then prevented or inhibited.
HIV may eventually mutate and develop resistance to the drugs. Many second-generation protease inhibitors continue to be effective until multiple mutations take place.

SLIDESHOW
A Timeline of the HIV/AIDS Pandemic See SlideshowWhat are the major side effects of protease inhibitors?
Protease inhibitors have a significant potential for interactions with certain drugs and foods. Some of the major side effects of protease inhibitors include the following:
- Gastrointestinal side effects such as
- Metabolic complications such as
- Dyslipidemia (abnormal level of blood fats)
- Lipodystrophy (abnormal distribution of fat tissue)
- Insulin resistance leading to diabetes mellitus
- Kidney or liver damage
- Abnormalities with the heart’s electrical activity
What are the FDA-approved protease inhibitors and their side effects?
Atazanavir (Reyataz)
Available as capsules and oral powder to be taken with food.
Side effects include:
- Indirect hyperbilirubinemia (high bilirubin levels in blood)
- Prolonged PR interval (abnormal heart rhythm)
- Hyperglycemia (high sugar level in blood)
- Skin rash
- Hyperlipidemia (high level of blood fats)
Darunavir (Prezista)
Available as tablets to be taken with food along with booster drugs such as ritonavir or cobicistat. Approved for antiretroviral treatment-naive patients or treatment-experienced patients without darunavir-resistance mutations.
Side effects include:
Fosamprenavir (Lexiva)
Available as tablets and oral suspension.
Side effects include:
Indinavir (Crixivan)
Available as capsules to be taken one hour before two hours after meal, or with skim milk or low-fat meal.
Side effects include:
- Nephrolithiasis (kidney stones)
- Nausea
- Indirect hyperbilirubinemia
- Hyperlipidemia
- Hyperglycemia
Lopinavir/ritonavir (Kaletra)
Available as tablets approved only for antiretroviral treatment–naïve patients or treatment-experienced patients without lopinavir-resistance mutations.
Side effects include:
- Nausea
- Vomiting
- Diarrhea
- Asthenia (abnormal physical weakness)
- Hyperlipidemia
- Hyperglycemia
Nelfinavir (Viracept)
Available as tablets and oral powder to be taken with food.
Side effects include:
- Diarrhea
- Hyperlipidemia
- Hyperglycemia
Ritonavir (Norvir)
Available as tablet, soft gelatin capsule and oral solution, to be taken with food. Used as a boosting drug for other protease inhibitors, or as sole protease inhibitor with gradual increase in dosage.
Side effects include:
- Nausea
- Vomiting
- Diarrhea
- Asthenia
- Hyperlipidemia
- Oral paresthesia (abnormal tingling or burning sensation or numbness in the mouth)
- Hyperglycemia
Saquinavir (Invirase)
Available as tablets and hard gelatin capsule, to be taken along with ritonavir as booster, with food or within two hours after meal.
Side effects include:
- Nausea
- Diarrhea
- Headache
- Hyperlipidemia
- Hyperglycemia
- PR and QT interval prolongation (abnormal heart rhythm)
Tipranavir (Aptivus)
Available as a soft gelatin capsule and oral solution, to be taken with ritonavir as a booster. Approved only for antiretroviral treatment-experienced patients with drug resistance.
Side effects include:
- Hepatotoxicity
- Rash
- Hyperlipidemia
- Hyperglycemia
- Intracranial hemorrhage (rare cases reported)
Summary
Protease inhibitors are one of the classes of drugs in the combination of drugs used for antiretroviral therapy (ART) for human immunodeficiency virus (HIV) infection. Protease inhibitors may be one class of drugs included in the ART cocktail for HIV to prevent its progression into AIDS (acquired immunodeficiency syndrome), which may cause death from secondary infection or cancer after the collapse of the immune system.
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HIV Early Signs and Stages
HIV (human immunodeficiency virus) weakens your immune system. Some people with HIV don’t have any symptoms, but those that do may experience mononucleosis-like or flu-like symptoms. There are 3 stages of HIV.
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How Long Can You Live with HIV?
HIV stands for human immunodeficiency virus. If someone has HIV it means that they have been diagnosed with the HIV infection. AIDS (acquired immune deficiency syndrome); however, is the most advanced or final stage of the HIV infection. In the case of an untreated HIV infection, the overall mortality rate is more than 90%. The average time from infection to death is eight to ten years.
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Human Immunodeficiency Virus (HIV)
HIV (human immunodeficiency virus) infection left untreated causes AIDS (acquired immunodeficiency syndrome). The human immunodeficiency virus (HIV) is a type of virus called a retrovirus, which can infect humans when it comes in contact with tissues that line the vagina, anal area, mouth, or eyes, or through a break in the skin. HIV infection is generally a slowly progressive disease in which the virus is present throughout the body at all stages of the disease. Three stages of HIV infection have been described. The initial stage of infection (primary infection), which occurs within weeks of acquiring the virus, often is characterized by the flu- or mono-like illness that generally resolves within weeks. The stage of chronic asymptomatic infection (meaning a long duration of infection without symptoms) lasts an average of eight to 10 years without treatment. The stage of symptomatic infection, in which the body's immune (or defense) system has been suppressed and complications have developed, is called the acquired immunodeficiency syndrome (AIDS). The symptoms are caused by the complications of AIDS, which include one or more unusual infections or cancers, severe loss of weight, and intellectual deterioration (called dementia). When HIV grows (that is, by reproducing itself), it acquires the ability to change (mutate) its own structure. These mutations enable the virus to become resistant to previously effective drug therapy. The goals of drug therapy are to prevent damage to the immune system by the HIV virus and to halt or delay the progress of the infection to symptomatic disease. Therapy for HIV includes combinations of drugs that decrease the growth of the virus to such an extent that the treatment prevents or markedly delays the development of viral resistance to the drugs. The best combination of drugs for HIV are those that effectively suppress viral replication in the blood and also are well tolerated and simple to take so that people can take the medications consistently without missing doses.
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What Is the Difference Between HIV-1 and HIV-2?
There are two main types of the human immunodeficiency virus (HIV), HIV-1 and HIV-2. HIV-1 is the most common type of HIV and accounts for 95% of all infections, whereas HIV-2 is relatively uncommon and less infectious. HIV-2 is mainly concentrated in West Africa, is less deadly and progresses more slowly.
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How Long Does It Take to See Signs of HIV?
The signs and symptoms of HIV may first appear within two to four weeks of infection. The stage in which the symptoms appear is called the stage of acute HIV infection. The symptoms appear due to the resistance or fight of the immune system against HIV. Early diagnosis and treatment of HIV gets the best results.
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What Are the Four Stages of HIV?
The World Health Organization (WHO) classifies human immunodeficiency virus (HIV) into four stages. Stage 1 (HIV infection): The CD4+ cell count is at least 500 cells per microliter. Stage 2 (HIV infection): The CD4+ cell count is 350 to 499. Stage 3 (advanced HIV disease or AHD): The CD4+ cell count is 200 to 349. Stage 4 (Acquired immunodeficiency syndrome [AIDS]): The CD4+ cell count is less than 200.
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How Long Does It Take to Notice Signs of HIV?
HIV (human immunodeficiency virus) is a virus that attacks and damages the cells of the immune system in the body. If left untreated, HIV can lead to the AIDS (acquired immunodeficiency syndrome) disease. AIDS is the final stage of HIV infection which occurs when the body’s immune system is severely damaged because of the virus and unusual infections result. Untreated, HIV infection has a mortality of 90%.
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HIV vs. AIDS
Human immunodeficiency virus causes HIV infection. Acquired immunodeficiency syndrome (AIDS) is a condition that results after HIV has extensively damaged a person's immune system. Risk factors for HIV and AIDS include use of contaminated needles or syringes, unprotected sex, STDs, receiving a blood transfusion prior to 1985 in the United States, having many sex partners, and transmission from a mother to her child.
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Can HIV be Cured Naturally?
HIV stands for human immunodeficiency virus. If someone has HIV it means that they have been diagnosed with the HIV infection. AIDS (acquired immune deficiency syndrome); however, is the most advanced or final stage of the HIV infection. It is important to get tested for HIV in the early stages of infection to minimize the damage to the immune system. Successful treatment aims to reduce HIV load to a level that is harmless to the body.
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How Do You Feel When You Have HIV?
About four weeks after contracting HIV (human immunodeficiency virus), you may experience flu-like symptoms including fever, rash, sore throat, nausea, swollen glands and achy joints. You may remain symptomless for some time, however. That doesn't mean you don't need treatment; HIV can quickly progress into AIDS, in which the immune system collapses and you die of a secondary cancer or infection.
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What Is Usually the First Sign of HIV?
Human immunodeficiency virus (HIV) attacks the cells of the immune system, leading to AIDS and death if left untreated. The first signs of the human immunodeficiency virus infection are flu-like symptoms, which mainly start around two to four weeks after getting HIV. This stage is known as acute HIV infection.
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HIV Medications List and Drug Charts
The ultimate goal of HIV treatment is getting the viral load down below detectable levels. As long as those viral load and antibody levels are below a proscribed range, people with HIV can stave off AIDS and other serious symptoms. Antiviral treatment options usually include combinations of two NRTIs, often referred to as "nucs," and a third drug, typically being a boosted protease inhibitor, a NNRTI, often called "non-nucs," and integrase strand transfer inhibitors.
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HIV/AIDS Infection Transmission and Prevention
HIV (human immunodeficiency virus) is spread through contact with genital fluids or blood of an infected person. The spread of HIV can occur when these secretions come in contact with tissues such as those lining the vagina, anal area, mouth, eyes (the mucus membranes), or with a break in the skin, such as from a cut or puncture by a needle.
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HIV/AIDS Testing: Diagnosis and Monitoring
HIV/AIDS diagnosis and monitoring have come a long way from the days when a diagnosis was a death sentence. Crucial parts of the effective treatment regimens developed in the last 40 years are consistent monitoring of the viral load (the amount of virus in the blood), and the immune cell count, which function as biological markers of the disease’s progression. Doctors also must test for drug resistance.
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HIV/AIDS Facts: What Is HIV?
HIV (human immunodeficiency virus) is the precursor infection to AIDS (acquired immunodeficiency syndrome). HIV is transmitted through blood and genital secretions; most people get it through sexual contact or sharing needles for illegal IV drug use. HIV can be controlled by a strict drug regimen, but left unchecked, it leads to AIDS. In AIDS, the immune system collapses and the body falls prey to secondary, opportunistic infections and cancers that typically kill the person.
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What Are the Side Effects of HIV Medications?
It’s important to know the potential side effects of all the drugs you take to control your HIV infection, as well as potential drug interactions. All of the NNRTIs (nonnucleoside analogue reverse transcriptase inhibitors), for example, are associated with important drug-drug interactions so they must be used with caution in patients on other medications. Learn more about the side effects of the drugs in standard treatment regimens.
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When should you start HIV medication?
Nearly everyone who is infected with HIV (human immunodeficiency virus) should start antiviral medication therapy as soon as they are diagnosed. Older guidelines recommended delaying treatment to help reduce the potential for drug side effects and viral resistance to treatment. Current thinking theorizes that early treatment may preserve more of the body's immune function.
Treatment & Diagnosis
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- HIV Treatment, Medications, and Prevention
- HIV Urine Test Approved
- HIV: Two Patients Face The Diagnosis
- HIV Treatment - To Interrupt or Not
- Unprotected Sex Between HIV-Infected Partners: What's the Harm?
- HIV Transmission and Progression to AIDS Continues
- Physical and Biochemical Changes in HIV Disease
- Babies On The Breast Of HIV Moms
- HIV / AIDS Conference Update 2005 - Index
- Retrovirus & Opportunistic Infections Part II
- Retroviruses and Opportunistic Infections Conf. 2/2006
- Can HIV Cause Kaposi's Sarcoma?
- Do You Need Antiretroviral Therapy for HIV with No Symptoms?
- Does HIV Cause Colorectal Cancer?
- Does Anti-Retroviral Therapy for HIV Cause Diabetes?
- How Long Should You Wait to Get an HIV Test?
- What Liver Problems Does HIV Cause?
- Does Circumcision Prevent HIV and AIDS?
- HIV Infection Facts, History, Causes, and Risk Factors
- HIV Tests, Symptoms, Signs, and Stages of Infection
- Baby "Cured" of HIV Infection
Medications & Supplements
- Symtuza (darunavir, cobicistat, emtricitabine, and tenofovir alafenamide)
- Genvoya
- Valcyte (valganciclovir hydrochloride)
- Dovato (dolutegravir and lamivudine)
- Prezcobix (darunavir and cobicistat)
- Trogarzo (ibalizumab-uiyk)
- Stribild (elvitegravir, cobicistat, emtricitabine, tenofovir disoproxil fumarate)
- dolutegravir
- Triumeq (abacavir, dolutegravir, and lamivudine)
- Prezista (darunavir)
- Mycobutin (rifabutin)
- Side Effects of Trizivir (abacavir, lamivudine, zidovudine)
- Pifeltro (doravirine)
- Epzicom (abacavir sulfate and lamivudine)

Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.