HIV Medicines

HIV, the human immunodeficiency virus, damages the immune system by destroying CD4 cells, a type of white blood cell that fights infection. As those cells are lost, the body has a harder time fighting off infections and certain HIV-related cancers. Without treatment, HIV can gradually destroy the immune system and progress to AIDS, acquired immunodeficiency syndrome, the final stage of HIV infection. Not everyone with HIV develops AIDS.

Antiretroviral therapy

Treating HIV with medicines is called antiretroviral therapy (ART), and it means taking a combination of medicines every day. ART is recommended for everyone with HIV. It does not cure the infection, but it helps people with HIV live longer, healthier lives and lowers the risk of passing the virus to others.

The medicines work by reducing the amount of HIV in the body, known as the viral load. That:

• gives the immune system a chance to recover, so that even with some HIV still present it should be strong enough to fight off infections and certain HIV-related cancers;
• reduces the risk of spreading HIV to others.

Types of HIV medicines

HIV medicines come in many types, called classes.

Medicines that block the enzymes HIV needs to copy itself. Stopping HIV from copying itself lowers the amount in the body.

• Nucleoside reverse transcriptase inhibitors (NRTIs) block an enzyme called reverse transcriptase.
• Non-nucleoside reverse transcriptase inhibitors (NNRTIs) bind to reverse transcriptase and later change it.
• Integrase inhibitors, also called integrase strand transfer inhibitors (INSTIs), block an enzyme called integrase.
• Protease inhibitors (PIs) block an enzyme called protease.

Medicines that keep HIV from infecting CD4 cells.

• Fusion inhibitors block HIV from entering the cells.
• CCR5 antagonists and post-attachment inhibitors block different molecules on CD4 cells. HIV has to bind to two types of molecules on a cell's surface to infect it, and blocking either one keeps it out.
• Attachment inhibitors bind to a specific protein on the outside of HIV, which keeps it from entering the cell.

Pharmacokinetic enhancers are sometimes taken with certain other HIV medicines to make them more effective. They slow the breakdown of the other medicine, so it stays in the body longer at a higher level.

Multidrug combinations combine two or more types of HIV medicines.

When to start

It is important to start HIV medicines as soon as possible after diagnosis, especially for people who:

• are pregnant;
• have AIDS;
• have certain HIV-related illnesses and infections;
• have early HIV infection, the first 6 months after becoming infected.

Taking HIV medicines

A person with HIV and their health care provider work out a treatment plan together, based on:

• possible side effects;
• possible interactions with other medicines the person takes;
• how many medicines they would need to take each day;
• any other health problems.

Take the medicines every day, as the provider instructs. Missing doses or taking them irregularly can make treatment fail and let the virus become resistant to the medicines.

HIV medicines can cause side effects. Most can be managed, but a few can be serious. Tell your provider about any side effects, and do not stop a medicine without talking to them first; there may be ways to manage the problem, and in some cases the provider may change the medicines.

Preventing HIV: PrEP and PEP

HIV medicines are also used for prevention:

• PrEP (pre-exposure prophylaxis) is for people who do not have HIV but are at very high risk of getting it.
• PEP (post-exposure prophylaxis) is for people who may have been exposed to HIV.

Sources

• MedlinePlus, U.S. National Library of Medicine, "HIV Medicines." https://medlineplus.gov/hivmedicines.html
• MedlinePlus credits the information to the Office of AIDS Research, NIH.