Fact Box on antiretroviral therapy

Antiretroviral drugs are the primary treatment for HIV/AIDS. These drugs work by suppressing the action of one or the other of two viral enzymes essential for replication of the HI virus. Effective therapy has been shown to reduce the number of new cells infected by HIV and to minimise the impact of HIV on the immune system. QUESTION: What types of regimens are available? ANSWER: There are three different types, firstly a single drug regimen (monotherapy). This is not recommended for the treatment of HIV infection as no currently available single ARV drug used by itself can provide significant, long-lasting suppression of HIV replication. Monotherapy does, however, play an important role in the prevention of mother-to-child transmission. Secondly, dual therapy, which is moderately effective. It is not the standard of care, but is better than no therapy at all, and should be considered in patients unable to afford highly active antiretroviral therapy (HAART). And finally, triple combinations, or HAART, is the combination of three synergistic antiretroviral agents. It remains the standard of care and substantial reductions in medication prices continue to make triple-drug regimens more affordable. Q: How do they work? A: HIV invades and takes over a CD4 cell (part of the body's immune response) to use it to make new copies of itself. This process of replication takes place in distinct stages, creating a lifecycle for HIV in a CD4 cell. Currently available antiretroviral agents are designed to interrupt this lifecycle by controlling the virus at specific stages. They block either of the two key viral enzymes required by HIV for intracellular viral replication, namely reverse transcriptase and protease. These can be classified into three classes:

1. Nucleoside reverse transcriptase inhibitors - they inhibit reverse transcriptase and copy the normal building blocks of HIV DNA.
2. Non-nucleoside reverse transcriptase inhibitors - they directly inhibit reverse transcriptase.
3. Protease inhibitors - they inhibit the protease enzyme and blocks late stages of HIV replication

Q: When should I start treatment? A: According to guidelines provided by Southern Africa's HIV Clinicians Society, ARV therapy should be deferred until patients are prepared to commit themselves to long-term treatment and maintaining good adherence to the therapy. Adequate counselling about safer sex practices must be provided to encourage prevention of new infections and reinfection. Treatment is recommended for individuals with HIV-related symptoms - thrush, wasting, unexplained fever or AIDS. Determining when to start therapy in individuals who do not display symptoms is more complicated. A patient with a CD4 cell count of less than 200 should be offered therapy. If the CD4 count is more than 200, treatment should be delayed. The CD4 test measures the number of CD4 or T-helper cells in the blood. The strength of your immune system is a good predictor of how you will fight infections. Q: Can I become resistant to the drugs? A: Because HIV reproduces itself so rapidly, mistakes are sometimes made. These are called mutations. This means that the new virus differs slightly from the original one. As the drugs target certain strains of HIV, other strains, including the mutated ones, will not be affected by these drugs and they become drug resistant. They are also able to produce more strains that are unaffected by drugs. It is therefore vital that the drugs be taken exactly as prescribed. Q: What are the side effects? Possible side effects of the drugs include anaemia (a decrease in red blood cells), diarrhoea, nerve problems and hepatitis (inflammation of the liver) - but these can be treated. SOURCES: ARV Therapy in Adults: Southern African HIV Clinicians Society Clinical Guidelines; JOURN-AIDS SEE ALSO: Special Report on AIDS treatment campaign Chronology of HIV/AIDS treatment access debate