If you take or have taken 1 or more treatment regimens to treat HIV, you are probably familiar with many of the antiretroviral (ARV) medications available today. You also may know that treatment can be complicated, especially if you have become resistant to a medication.

Make sure you are familiar with the different classes of medications that treat HIV, so that you can have an informed conversation with your doctor about finding a treatment that works, and will keep working, for you.

HIV Treatment Goals

HIV medications, or antiretroviral (ARV) medications, which are used to treat the HIV virus, cannot cure the disease, but they may keep the virus from reproducing or making copies of itself.

HIV medication has 4 major goals:

* Extend life expectancy and quality of life
* Prevent HIV from progressing
o Reduce the viral load (the amount of HIV virus in the blood) to undetectable levels (less than 50 copies/milliliter) for as long as possible
o Limit the development of resistance (when the virus no longer responds) to ARV medications
* Restore and preserve the immune system to normal
o Keep CD4 cell counts in the normal range or raise CD4 counts if they are too low
o Resist other infections
* Reduce transmission of HIV to others.

Drug Classes

Four classes of HIV medications fight against HIV. Each class is defined by how it attacks the virus.
Class Function
Nucleoside reverse transcriptase inhibitors (NRTIs), also known as "nukes", nucleoside analogs, or backbone

* Abacavir (ABC)
* Abacavir + Lamivudine (ABC + 3TC)
* Abacavir + Lamivudine + Zidovudine (ABC + AZT + 3TC)
* Didanosine (ddl)
* Emtricitabine (FTC)
* Tenofovir DF + Emtricitabine (TDF + FTC)
* Lamivudine (3TC)
* Stavudine (d4T)
* Tenofovir DF (TDF or Bis(POC) PMPA)
* Zalcitabine (ddC)
* Zidovudine (AZT or ZDV)
* Zidovudine + Lamivudine (AZT + 3TC)

The oldest class of antiretroviral (ARV) medications, NRTIs block HIV's ability to copy a cell's DNA, which the virus needs to make copies of itself.
Non-nucleoside reverse transcriptase inhibitors (NNRTIs)

* Efavirenz (EFV)
* Nevirapine (NVP)

NNRTIs block the same protein as the NRTI, but are chemically different. Resistance to this class of medications develops quickly if not used in combination with an NRTI.
Protease inhibitors (PIs)

* Atazanavir (ATZ)
* Darunavir (DRV)
* Fosamprenavir (FPV)
* Indinavir (IDV)
* Lopinavir + Ritonavir (LPV)
* Nelfinavir (NFV)
* Ritonavir (RTV)
* Saquinavir (SQV)
* Tipranavir (TPV)

PIs block protease, an enzyme that the HIV virus needs to make copies of itself. As a group, PIs are very potent and relatively well tolerated.
Fusion inhibitors (FIs)

* Enfuvirtide (T-20)

The newest class of available ARV medications, FIs block HIV from entering the body's healthy cells. This medication must be administered by injection.

Combination Therapy

Therapy for HIV usually includes 3 or more HIV medications from the classes outlined above. The combination of these HIV medications is designed to keep the virus from making copies of itself, while minimizing potential side effects and pill burden. These combinations are referred to as HAART, highly active antiretroviral therapy.

The International AIDS Society lists the following potential initial combination regimens for the treatment of HIV:

* 2 NRTIs + 1 PI with or without ritonavir (for boosting)
* 2 NRTIs + 1 NNRTI

Factors such as adherence, drug resistance, and side effects may cause a HAART regimen to fail. If this happens, your doctor will make a decision about how to change your medication regimen based partly on your treatment history, how many medication combinations you have tried, and whether you have become resistant to an antiretroviral (ARV) medication.