Last updated, March 2008.

Next due for review, March 2009.

Anti-HIV treatment cannot cure HIV. But is can mean a longer, healthier life.

Taking a combination of drugs that work against HIV (these are often called antiretroviral drugs) can lower the amount of HIV in the blood to undetectable levels. This means that HIV is prevented from damaging the immune system so it is able to fight infections.

There are different types, or classes, or anti-HIV drugs and each class works against HIV in a different way. Anti-HIV treatment normally includes three drugs from two different classes of drug.

Classes of anti-HIV drugs

**Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs).

**Non-nucleoside reverse transcriptase inhibitors (NNRTIs).

**Protease inhibitors (PIs).

**Fusion and entry inhibitors.

**Integrase inhibitors.

Most people take a combination that includes two NRTIs and either an NNRTI or a protease inhibitor.

Treatment with fusion, entry and integrase inhibitors is usually reserved for people who have taken a lot of anti-HIV treatment in the past.

NRTIs and NNRTIs

These drugs target a substance called reverse transcriptase that HIV uses to infect immune system cells.

There are three types of drug that work against reverse transcriptase. These are:

NRTIs: abacavir (Ziagen), AZT (zidovudine, Retrovir), ddI (didadosine, Videx), 3TC (lamivudine, Epivir), d4T (stavudine, Zerit), and FTC (emtricitabine, Emtriva).

Some NRTIs have been combined into a single pill to make them easier to take. These are abacavir and 3TC (Kivexa), AZT and 3TC (Combivir), and abacavir, AZT and 3TC (Trizivir).

Nucleotide reverse transcriptase inhibitor: tenofovir (Viread) works against HIV in a similar way to NRTIs. It is available in a combined pill with FTC called Truvada.

NNRTIs: there are two NNRTIs approved for use called efavirenz (Sustiva) and nevirapine (Viramune). A third NNRTI called etravirine (Intelence) is expected to be approved later in 2008.

Efavirenz, FTC and tenofovir are available in a combination pill called Atripla.

Protease inhibitors

Protease is an enzyme in HIV. It is attacked by protease inhibitors.

It is usual to take what is called a ‘boosted’ protease inhibitor. These have their potency increased by the addition of a small dose of a second protease inhibitor called ritonavir (Norvir).

The most widely used protease inhibitor for people taking anti-HIV treatment for the first time is lopinavir/ritonavir (Kaletra). This is a combination pill.

Other boosted protease inhibitors available for people starting anti-HIV treatment are fosamprenavir (Telzir)/ritonavir and saquinavir (Invirase)/ritonavir.

Atazanavir (Reyataz)/ritonavir has been shown to work well in people starting anti-HIV treatment.

Darunavir (Prezista)/ritonavir and tipranavir (Aptivus)/ritonavir are reserved for people who have taken a lot of anti-HIV drugs in the past and have resistant virus.

Two other protease inhibitors, indinavir (Crixivan) and nelfinavir (Viracept) cannot be boosted by ritonavir and are now used very rarely.

Fusion and entry inhibitors

Drugs from these classes prevent HIV from infecting cells. Their use is normally reserved for people who have taken a lot of anti-HIV drugs in the past.

There is one fusion inhibitor. It is called T-20 (enfuvirtide, Fuzeon).

One entry inhibitor, or CCR5 inhibitor, is also approved. It is called maraviroc (Celsentri). For this drug to work you need to have what’s called a ‘CCR5  co-receptor’ on the surface of HIV. Not everybody who has taken a lot of HIV drugs in the past has this. Your clinic will conduct a test called a tropism test to see if you are suitable for treatment with a CCR5 inhibitor.

Integrase inhibitors

These prevent HIV from integrating with immune system cells. One drug from this class has been approved, it is called raltegravir (Isentress) and its use is reserved for people who have taken a lot of anti-HIV drugs in the past.

When to start treatment

If you are unwell because of HIV, then you should start taking anti-HIV drugs.

It is also recommended to start taking anti-HIV treatment when your CD4 cell count falls to around 350.

What to start treatment with

It is currently recommended to start with either a NNRTI (normally efavirenz). This is taken with Truvada (FTC and tenofovir).

A boosted protease inhibitor is an option for some people, and Kivexa (abacavir and 3TC) may be an alternative to Truvada for people with kidney problems.

Side-effects

All drugs cause side-effects. The side-effects that your HIV can cause should be explained to you before you start taking them. Side-effects often go away after a few weeks. Tell your doctor about side-effects, particularly rashes.

Resistance

HIV can develop resistance to the drugs use to treat it. You should have a resistance test before you start or change treatment to make sure you are taking the best possible drugs for your HIV.

Taking your drugs

Taking your drugs properly can help prevent resistance developing. You can read more about this in the factsheets 'adherence' and 'adherence tips.'