Of course. This is a very important topic. Here is a comprehensive overview of HIV antiretroviral drugs, how they work, the current treatment strategies, and the different classes of medications.
The Goal of HIV Treatment
The primary goal of HIV treatment is to reduce the amount of virus (HIV) in the body to an undetectable level. This is achieved using a combination of drugs known as Antiretroviral Therapy (ART).
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Undetectable = Untransmittable (U=U): When a person with HIV is on effective ART and has an undetectable viral load, they cannot sexually transmit HIV to others. This is a monumental and proven scientific fact.
How HIV Drugs Work: The Major Classes
HIV drugs work by blocking the virus at different stages of its life cycle. Because HIV mutates quickly, using a combination of drugs from different classes is essential to prevent the virus from becoming resistant.
Here are the main classes of antiretroviral drugs:
1. Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTIs)
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How they work: They act as faulty building blocks. When HIV tries to copy its RNA into DNA (using an enzyme called reverse transcriptase), these fake building blocks stop the process, preventing the virus from replicating.
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Common Examples:
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Tenofovir disoproxil fumarate (TDF)
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Tenofovir alafenamide (TAF) - a newer version with fewer side effects
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Emtricitabine (FTC)
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Abacavir (ABC)
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Lamivudine (3TC)
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Note: NRTIs are often combined into a single pill (e.g., FTC/TAF or ABC/3TC).
2. Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
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How they work: They bind directly to the reverse transcriptase enzyme, deforming it so it can't work properly. It's a different way of blocking the same step as NRTIs.
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Common Examples:
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Efavirenz (EFV)
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Rilpivirine (RPV)
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Doravirine (DOR)
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Etravirine (ETR)
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3. Protease Inhibitors (PIs)
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How they work: They block the protease enzyme. In the late stages of replication, HIV needs to cut long chains of protein into smaller pieces to create new, mature viruses. PIs prevent this cutting, leading to the production of non-infectious, immature viruses.
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Common Examples:
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Darunavir (DRV)
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Atazanavir (ATV)
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Note: PIs are almost always taken with a pharmacokinetic enhancer (see below).
4. Integrase Strand Transfer Inhibitors (INSTIs)
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How they work: They block the integrase enzyme, which HIV uses to insert its genetic material into the DNA of the host CD4 cell. Without integration, the virus cannot take over the cell's machinery to reproduce.
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Common Examples: This is the most recommended and widely used class today due to its high effectiveness and good safety profile.
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Dolutegravir (DTG)
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Bictegravir (BIC)
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Raltegravir (RAL)
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Cabotegravir (CAB) - used in long-acting injectable regimens.
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5. Entry Inhibitors
This class includes drugs that block HIV from entering the CD4 cell.
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CCR5 Antagonists: Blocks the CCR5 co-receptor on the cell surface (e.g., Maraviroc - MVC). A special test is needed to see if a person's virus uses this receptor.
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Fusion Inhibitors: Prevents the fusion of the HIV envelope with the CD4 cell membrane (e.g., Enfuvirtide - T-20). This is an injectable drug used mostly in salvage therapy for heavily treatment-experienced people.
6. Pharmacokinetic Enhancers ("Boosters")
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How they work: These are not antivirals themselves. They slow down the breakdown of other HIV drugs (like PIs and some INSTIs) in the body, which allows the main drug to be taken at a lower dose and less frequently, while maintaining higher and more effective levels in the blood.
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Common Example: Cobicistat (COBI) and Ritonavir (RTV).
Modern HIV Treatment Regimens
Today, treatment for most people starting HIV therapy is simple, highly effective, and well-tolerated. The standard of care is a single-tablet regimen (STR).
First-Line Regimens (Most Common):
These are typically combinations of two NRTIs + one drug from another class (usually an INSTI).
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2 NRTIs + 1 INSTI
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Biktarvy: A single pill containing Bictegravir + Emtricitabine + Tenofovir alafenamide. This is one of the most prescribed regimens globally.
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Dolutegravir + Lamivudine + Tenofovir (or a similar NRTI backbone).
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2 NRTIs + 1 NNRTI (less common for new starts now, but still used)
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e.g., Efavirenz/Emtricitabine/Tenofovir (Atripla).
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Long-Acting Injectable Therapy
A major breakthrough in HIV treatment is the availability of long-acting injectable regimens.
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Cabenuva: A combination of Cabotegravir (INSTI) and Rilpivirine (NNRTI).
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How it works: It is given as an injection by a healthcare professional once a month or once every two months, replacing daily pills.
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Benefit: This offers a significant improvement in quality of life and privacy for many people.
Key Considerations
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Adherence: Taking medication exactly as prescribed is critical to maintain an undetectable viral load and prevent drug resistance.
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Side Effects: Modern drugs have far fewer and less severe side effects than early HIV medications. Common short-term side effects can include nausea, headache, or dizziness, which often go away. Long-term considerations can include effects on kidneys, bones, or cholesterol.
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Drug Interactions: HIV medications can interact with many other drugs (including over-the-counter meds and supplements). It is essential for your doctor and pharmacist to know all the medications you are taking.
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No Cure, But Manageable: ART is not a cure for HIV. It controls the virus, allowing people with HIV to live long, healthy lives. If treatment is stopped, the virus will rebound.
Disclaimer
This information is for educational purposes only. The choice of an HIV regimen is a complex medical decision that must be made by a qualified healthcare professional in consultation with the individual patient, based on their specific health status, viral resistance tests, and other factors.
If you or someone you know is living with HIV, the best source of information and care is an infectious disease specialist or a dedicated HIV clinic.
