Comprehensive, up-to-date information on HIV/AIDS treatment, prevention, and policy from the University of California San Francisco

Once you and your doctor have decided that you should start taking drugs for HIV, your doctor will come up with a personal treatment plan for you. You will find it easier to understand your plan if you learn about the different drugs available and what they do.

Some people chose to start anti-HIV medicines (antiretrovirals, or ARVs) as part of a study or clinical trial. A study may be evaluating a new HIV medicine that is not yet approved by the U.S. Food and Drug Administration (FDA), or a new combination of medicines or treatment strategies targeted to a specific population. If you are interested in learning more about starting ARV treatment as part of a study, talk to your provider about studies that are available in your area and that might be a good fit for you. More information about participating in clinical trials can be found in the section After You Start Therapy. There are many websites that catalogue available clinical trials; one of the most comprehensive is www.clinicaltrials.gov.

Anti-HIV drugs are also called antiretroviral drugs or antiretrovirals. They work because they attack the HIV virus directly. The drugs cripple the ability of the virus to make copies of itself.

There are 6 main classes of anti-HIV drugs:

		Nucleoside Reverse Transcriptase Inhibitors (NRTIs or "nukes")

		Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs or "non-nukes")

		Protease Inhibitors (PIs)

		Integrase Inhibitors

		Chemokine Coreceptor Antagonists (CCR5 Antagonists)

		Fusion or Entry Inhibitors

Each group attacks HIV in its own way and helps your body fight the infection. Most of these drugs come as tablets or capsules. Several of these drugs may be combined into one tablet to make it easier to take your medications. These are known as fixed-dose combinations.

Nucleoside reverse transcriptase inhibitors

The first group of antiretroviral drugs is the nucleoside reverse transcriptase (pronounced "trans-krip-tase") inhibitors (NRTIs). NRTIs were the first type of drug available to treat HIV. They remain effective, powerful, and important medications for treating HIV when combined with other drugs. They are better known as nucleoside analogues or "nukes." When the HIV virus enters a healthy cell, it attempts to make copies of itself. It does this by using an enzyme called reverse transcriptase. The NRTIs work because they block that enzyme. Without reverse transcriptase, HIV can't make new virus copies of itself. The following is a list of the drugs in the NRTI class: Emtriva (emtricitabine) Epivir (3TC, lamivudine) Retrovir (AZT, zidovudine) Videx-EC (ddI, didanosine) Viread (tenofovir) Zerit (d4T, stavudine) Ziagen (abacavir) Several of the NRTI drugs may be combined into one tablet to make it easier to take your medications. These drugs are known as fixed-dose combinations: Combivir (Retrovir + Epivir) Epzicom (Epivir + Ziagen) Trizivir (Retrovir + Epivir + Ziagen) Truvada (Viread + Emtriva)

Nonnucleoside reverse transcriptase inhibitors

The second type of antiretroviral drugs is the non-nucleoside reverse transcriptase inhibitors (NNRTIs). These drugs are sometimes called non-nucleosides or "non-nukes." These drugs also prevent HIV from using reverse transcriptase to make copies of itself, but in a different way. These NNRTIs are available: Edurant (rilpivirine) Intelence (etravirine) Rescriptor (delavirdine) Sustiva (efavirenz) Viramune (nevirapine)

Protease inhibitors

The third group of drugs is the protease (pronounced "pro-tee-ase") inhibitors (PIs). Once HIV has infected a cell and made copies of itself, it uses an enzyme called protease to process itself correctly so it can be released from the cell to infect other cells. These medicines work by blocking protease. Nine PIs are available: Aptivus (tipranavir) Crixivan (indinavir) Invirase (saquinavir) Kaletra (lopinavir + ritonavir combined in one tablet) Lexiva (fosamprenavir) Norvir (ritonavir) Prezista (darunavir) Reyataz (atazanavir) Viracept (nelfinavir) Note: Many PIs are recommended or approved for use only with low-dose Norvir, which "boosts" their effect.

Integrase inhibitors

This class of anti-HIV drugs works by blocking an enzyme (HIV integrase) that the virus needs in order to splice copies of itself into human DNA. Isentress (raltegravir) No brand name. (elvitegravir). At this time elvitegravir is available only in a fixed dose combination tablet (see Multi-class drug combinations).

CCR5 inhibitors

To infect a cell, HIV must bind to two types of molecules on the cell's surface. One of these is called a chemokine coreceptor. Drugs known as chemokine coreceptor antagonists block the virus from binding to the molecules. Selzentry (maraviroc)

Fusion inhibitors

The fusion or entry inhibitors work by stopping the HIV virus from getting into your body's healthy cells in the first place. Only one fusion inhibitor is available at present, and it needs to be injected: Fuzeon (enfuvirtide, T-20)

Multi-class drug combinations

At present there are three options that combine drugs from two different groups into a complete HIV drug regimen. A patient prescribed one of these combinations takes only one tablet, once a day. Despite the convenience, these combination tablets are not for everyone--each has specific possible side effects or dosing requirements that should be considered. You and your doctor can decide whether these drug combinations are right for you. Atripla (Sustiva + Emtriva + Viread) Complera (Edurant + Emtriva + Viread) Stribild (elvitegravir + Emtriva + Viread)

Now that you have learned a little about the types of drugs that are available and how they work, you may be wondering how your health care provider will know which medicines you should take.

Anti-HIV drugs are used in combination with one another in order to get the best results. The goal is to get the viral load as low as possible (to levels that are undetectable by standard laboratory tests) for as long as possible.

Anti-HIV medicines do different things to the virus--they attack it in different ways--so using the different drugs in combination works better than using just one by itself. Combinations usually include three antiretroviral drugs. Except in very special circumstances, anti-HIV drugs should never be used one or two at a time. Using only one or two drugs at a time can fail to control the viral load and let the virus adapt (or become resistant) to the drug. Once the virus adapts to a drug, the drug won't work as well against the virus, and maybe it won't work at all.

There is no one combination of HIV medications that works best for everyone. Each combination has its pluses and minuses.

When drugs are used together, the therapy is called combination therapy (or antiretroviral therapy (ART), or highly active antiretroviral therapy (HAART)).

So, how will your doctor know which combination to choose? You and your doctor can consider the options, keeping certain things in mind, such as possible side effects, the number of pills you'll need to take, and how the drugs interact with each other and with other medications you may take.

"Adherence" refers to how well you stay on your treatment plan--whether you take your medications exactly as your health care provider tells you.

If you follow your doctor's instructions about how to take your medicine, the anti-HIV drugs will work well to lower the amount of virus in your blood. Taking your drugs correctly increases your likelihood of success.

But, if you miss doses, or don't follow a regular schedule, the level of the drug in your body goes up and down. The virus then has the opportunity to make copies of itself more rapidly. That increases your viral load.

Following your treatment schedule also helps to prevent drug resistance. If you miss a dose, the virus may make new and different types of itself that the drug can no longer combat.

It's challenging for some patients to stick to their HIV drug treatment plan. Most plans involve taking several pills every day, and some of the drugs have unpleasant side effects.

Before you start a treatment plan, you should:

		Get your doctor to write everything down for you: names of the drugs, what they look like, how to take them (with food or not), and how often to take them. This way, you'll have something to look at in case you forget what you're supposed to do.

		With your doctor's help, develop a plan that works for you.

Quick Tips: Adherence Get a pillbox and fill it at the beginning of each week. Take your medicine at the same time each day. (Use a watch with an alarm or get a beeper.) Get a medication "diary" or notebook. In it, you can write the names of your drugs, and then check off each dose as you take it. (See the "Resources" section for a sample diary.) Plan ahead for changes in your normal routine (for example, if you will be out all day, or if you're going on vacation). Make sure you always have enough medicine! Call your doctor or pharmacist if you are running low.

It is important that you tell your doctor right away about any problems you are having with your treatment plan. Keeping a medication diary can help you remember any problems you have.