3.3. Antiretrovirals and therapy regimens
The main goals of HIV treatment are maximum extension of human life, improving quality of life, and reducing the risk of HIV transmission. Thanks to advances of modern medicine, the frequency of diseases associated with immune deficiency and mortality of HIV-infected patients have decreased.
Highly active antiretroviral therapy (HAAT, ARVT, ART) is currently recommended for all people infected with HIV. There are several groups of antiretrovirals:
- NRTIs (nucleoside reverse transcriptase inhibitors), NtRTIs (nucleotide reverse transcriptase inhibitors) and NNRTIs (non-nucleoside reverse transcriptase inhibitors) inhibit the replication of the viral RNA inside the cell.
- Protease inhibitors aim to stop HIV from replicating itself.
- Integrase inhibitors prevent the viral DNA from integrating into the CD4 cell nucleus.
- Entry inhibitors prevent the fusion of the virus and the CD4receptor cell membrane (T-lymphocytes).
Different medications block the virus at different stages in its life cycle, and, as a rule, the management includes the use of a combination of multiple medications to provide an extensive attack on the virus.
There is a wide range of therapy regimens and you can read about medication combinations in different HIV treatment guidelines of EU countries, the United States, Russia, etc.
Currently, the three-component therapy is the most common HIV treatment system.
The treatment combines several therapies at once:
- Viral therapy aims at blocking virus replication in order to reduce the viral load and hold it at a low level.
- Immunological therapy aims at restoring the immune system to increase the level of T-lymphocytes and stabilize body defenses against infections.
- Clinical therapy aims at increasing the length and quality of life for people with HIV infection, and to prevent the development of the AIDS stage and its manifestations.
The dosing and administration for HIV treatment is assessed for each patient taking into account his health status and possible side effects. The combination therapy is chosen from three or four components, which makes it possible to reduce not only the virus replication in the body, but also its natural mutations.
HIV may develop persistence to a particular medication, if it is taken intermittently or in insufficient doses. Such persistence is called resistance.
When prescribing therapy, the doctor takes into account the ability of HIV to mutate and develop resistance, if the virus becomes resistant to one medication, the other components of the therapy will be effective.
To find an effective dosage regimen, the doctor should also take into consideration the patient’s professional occupation, in particular those activities which are associated with specific working conditions or requiring concentration. Some medications from the HAART schemes may affect the performance capacity.
In addition, in selecting antiretroviral therapy the doctor should always take into account HAART interaction with the other medications. If one takes other medications in addition to antiretrovirals or undergoes a course of chemotherapy for tuberculosis, a doctor should always be consulted regarding interaction of pharmaceutical components, because the HAART effectiveness can seriously degrade in this case or have side effects.
The successful outcome of therapy depends upon patients' adherence to treatment recommendations:
- Regularity of medication intake,
- Adherence to the dosing regimen,
- Continuity of treatment, compliance
If a person takes HAART on a regular basis, the medication concentration in the blood is sufficient to suppress and prevent viral replication. In this case, if a dose of medication is not taken on time efficacy is not affected because the concentration of medicine in the blood is sufficient to suppress the virus. However, it is very important that the noncompliance with therapy regimes be not regular. Risks arise only when deviating from dosage regimen is repeated or systematic. Such noncompliance may result in increased viral load or cause resistance to HIV medications, and this, in turn, can lead to the disease progression.
The original medications and generics
Medications tend to have two names: the international non-proprietary name (INN), which is given to it according to the active substance, and the commercial (trade) name. A prescription is always issued for active substance (INN) with indication of its quantity in the dosage form.
Medications with the same INN can often vary greatly in price. The reason for this is the presence on the market of the original and reproduced drugs (generics). Generics are the analogues of the original drugs, which usually cost less than the original ones because their manufacturers had practically no expenditures on research, development and advertising, which make up a significant portion of the cost of the original drugs.
Generics have the same effectiveness and safety, contain the same active ingredient and are the same strength, as the original medications.