How Do Antiretroviral Agents Work?
HOW DO ANTIRETROVIRAL AGENTS WORK?
Antiretroviral (ARV) agents are a class of drugs used to help control human immunodeficiency virus (HIV) infection. Although they do not cure HIV, they may decrease the chances of developing acquired immunodeficiency syndrome and HIV-related illnesses such as serious infections or cancer. They reduce the number of HIV particles in the body (lowering viral load), thus causing the immune system to work better and improving the quality of life.
HIV depletes the immune cells, CD4 T cells that the body needs for an effective immune response. Thus, the body's ability to fight diseases reduces, leaving it vulnerable to an ever-widening range of opportunistic infections. For HIV to replicate, it must go through various stages of its life cycle:
- Attach to and enter a host cell (entry/attachment)
- Translate its viral RNA into DNA (reverse transcriptase)
- Integrate its genetic coding into the host cell's nucleus (integration)
- Create the building blocks by which new viruses are formed (protease catalysis)
- Start churning out copies of itself (budding)
The World Health Organization recommends that all adults and adolescents with HIV commence ARV treatment when their CD4 cell counts reach or fall below 350 cells/mm3.
ARV agents are administered via oral and intravenous routes. If an individual with a nonresistant strain of HIV takes the appropriate antiretroviral treatment (ART) as directed, the replication of HIV can be effectively suppressed in approximately 80% of cases. If medications are not taken as directed (for example, taking it occasionally or intermittently), it can increase the likelihood of resistance where the HIV strain adapts to the treatment and make ARV medications ineffective. If one antiretroviral drug is unable to suppress a certain mutation, the other one or two drugs usually can work by blocking a different stage of the cycle.
A combination of "cocktails" of at least two of them is called ART. The following are the different categories of the antiretroviral drug:
- Nucleoside reverse transcriptase inhibitors (NRTI)
- Non-NRTI
- Protease inhibitors
- Entry inhibitors
ARVs work in the following ways:
- ARV drugs work by blocking different stages of the HIV life cycle.
- In this way, they can suppress the HIV infection but cannot eliminate it from the body.
- HIV is an RNA virus that uses a range of viral enzymes to incorporate itself into human DNA within certain types of immune cells.
- Once present in the DNA strand, HIV can use the cell’s mechanisms to create more HIV viral particles to infect more human immune cells.
- HIV binds to receptors on the surface of human immune cells, primarily CD4+ T-helper immune cells (called CD4+ cells) that fight infections.
- The HIV then enters the cell cytoplasm where an enzyme called viral reverse transcriptase creates viral DNA from HIV RNA.
This DNA moves into the cell nucleus where it is incorporated into the human DNA strand by viral integrase.
As normal cellular DNA transcription takes place, HIV DNA within the human strand is also transcribed, producing HIV-derived mRNA.
This mRNA is then translated into proteins required to generate more HIV viral particles by viral protease.
ARV drugs work by inhibiting various viral enzymes critical to the HIV replication cycle, specifically reverse transcriptase, integrase, and protease, from which the ARV drug names are drawn.
WHAT ARE SIDE EFFECTS OF ANTIRETROVIRAL AGENTS?
Taking these medications along with practicing safer sex and making other lifestyle changes may decrease the risk of transmitting (spreading) HIV to other people.
Common side effects include:
- Nausea
- Headache
- Vomiting
- Malaise (a sense of unease or a lack of well-being)
- Fatigue
- Diarrhea
- Loss of appetite
Other rare side effects include:
- Musculoskeletal pain
- Hypertriglyceridemia (elevated level of triglycerides [a type of lipid] in the bloodstream)
- Viral respiratory infections
- Fever
- Insomnia (trouble falling and/or staying asleep)
- Dizziness (feeling faint, weak, or unsteady)
- Depression
- Anxiety
- Unexplained weight loss
- Numbness/tingling of the hands/feet/arms/legs
- Thrombocytopenia (low blood platelet count)
- Fast/pounding/irregular heartbeat
Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.
