MODULE 3 HIV AND AIDS PROPHYLAXIS
3.1 What is HIV Antiretroviral Treatment?
This is the main type of treatment for HIV or AIDS. It is not a cure, but it can stop people from becoming ill for many years. The treatment consists of drugs that have to be taken every day for the rest of someone's life. To understand more about the treatment you need to have some basic knowledge of HIV and AIDS.
Antiretroviral treatment for HIV infection consists of drugs which work against HIV infection itself by slowing down the replication of HIV in the body. The drugs are often referred to as:
• antiretrovirals
• anti-HIV drugs
• HIV antiviral drugs
For antiretroviral treatment to be effective for a long time, it has been found that the patient needs to take more than one antiretroviral drug at a time. This is what is known as combination therapy. The term Highly Active Antiretroviral Therapy (HAART) is used to describe a combination of three or more anti-HIV drugs.
When HIV replicates (makes new copies of itself) it often makes mistakes. This means that within any infected person there are many different strains of the virus. Occasionally, a new strain is produced that happens to be resistant to the effects of an antiretroviral drug. If the person is not taking any other type of drug then the resistant strain is able to replicate quickly and the benefits of treatment are lost. Taking two or more antiretrovirals at the same time vastly reduces the rate at which resistance develops.
3.2 Antiretroviral Drugs
There are four groups of anti-HIV drugs. Each of these groups attacks HIV in a different way. They include:
• Nucleoside/Nucleotide Reverse Transcriptase Inhibitors
• Non-Nucleoside Reverse Transcriptase Inhibitors
• Protease Inhibitors
• Fusion or Entry Inhibitors
We shall briefly explain each of the four groups.
The first group of antiretroviral drugs consistsis of the Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTIs).
These were the first type of drugs available to treat HIV infection in
1987. NRTIs (also known as nucleoside analogues or nukes) interfere with the action of an HIV protein called reverse transcriptase, which the virus needs to make new copies of itself. NRTIs are sometimes called the "backbone" of combination therapy because most regimens contain at least two of these drugs.
The second group of antiretroviral drugs is made up of the Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs), which started to be approved in 1997. Like the nukes, NNRTIs (also known as non-nucleosides or non-nukes) stop HIV from replicating within cells by inhibiting the reverse transcriptase protein.
The third type of antiretrovirals is the Protease Inhibitor (PI) group.
The first protease inhibitor was approved in 1995. Protease inhibitors, as the name implies, inhibit protease, which is another protein involved in the HIV replication process.
The fourth group of antiretrovirals comprises Entry Inhibitors, including Fusion Inhibitors. One of these drugs - commonly called T-20 - has been licensed both in the US and in Europe since 2003, but it is meant only for use by people who have already tried other treatments.
The T-20 fusion inhibitor differs from the other antiretrovirals in that it needs to be injected (otherwise it would be digested in the stomach).
Entry inhibitors prevent HIV from entering human cells.
3.3 Combination of Drugs/Highly Active Antiretroviral Therapy (HATT)
Highly Active Antiretroviral Therapy consists of a combination of three or more drugs. The most common combination given to those beginning treatment consists of two NRTIs combined with either an NNRTI or a
"boosted" protease inhibitor. Ritonavir (in small doses) is the drug most commonly used to boost a protease inhibitor. An example of a common combination is the two NRTIs zidovudine and lamivudine combined with the NNRTI efavirenz.
SELF ASSESSMENT EXERCISE 1
What is the peculiarity of the non-nucleoside reverse transcriptase inhibitors and the entry inhibitors?
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Although coverage has improved greatly in recent years, most people living with HIV in the developing world still have no access to
antiretroviral treatment. Instead, the best they can hope to receive is treatment for the diseases that occur as a result of a weakened immune system, which are known as opportunistic infections. Such treatment has only short-term benefits because it does not address the underlying immune deficiency itself.
4.0 CONCLUSION
Starting HIV antiretroviral treatment is a very important decision to be taken by the health care provider once the initial assessment of the patient shows a positive sign of HIV/AIDS infestation. Treatment must be adhered to in spite of side effects while efforts should be made to prevail on the conscious ego of the client to comply despite the challenge and other challenges.
5.0 SUMMARY
This unit has examined various antiretroviral treatments for HIV/AIDS positive and carriers. A combination of drugs has been found to be effective in the overall management.
6.0 TUTOR MARKED ASSIGNMENT
Describe three classes of antiretroviral drugs used for HIV management Answer to Self Assessment Exercises
While the non-nucleosides or non-nukes stop HIV from replicating within cells by inhibiting the reverse transcriptase protein, the entry inhibitors prevent HIV from entering human cells.
7.0 REFERENCES/FURTHER READINGS
TDR News (2007). Enhancing Drug Discovery for Neglected Tropical Diseases. Published by WHO, Geneva
UNAIDS (2001). Sources and Prices of Selected Drugs and Diagnostics for People Living with HIVS/AIDS.
WHO (2006) Guidelines on Co-trimoxazole Prophylaxis for HIV-related Infections among Children, Adolescents and Adults in Resource-Limited Settings Other site