HIV Overview

As defined by the U.S. Food and Drug Administration (FDA), an investigational HIV drug is an experimental drug that is being studied to determine:

• Whether it is safe and effective.

• How the drug may be used in a specific situation (adults, children, pregnant people, etc.).

• How much of the drug is needed.

• Information about the potential benefits and risks of taking the drug.

Investigational HIV drugs are studied in a series of medical research studies called clinical trials. Once an investigational HIV drug has been proven safe and effective in a clinical trial, drug sponsors formally propose the FDA approve it as a new medicine for sale and marketing in the U.S. by submitting a New Drug Application. After reviewing the clinical trials, the FDA may approve the drug for general use or sale in the United States.

Since the first antiretroviral drug was described, HIV treatment has come a long way. Today, there are over 40 FDA-approved drugs to treat HIV. Most people with HIV can live a normal life span by taking a combination of two or more HIV drugs. However, some people find it hard to remember to take their prescribed HIV medicine every day, especially if they have substance use or mental health disorders. Others develop drug-resistant strains of HIV, which means that the virus mutates so that the medications they take are no longer effective. Many times, these two factors go together: forgetting to take HIV medicines allows HIV to multiply, which increases the risk of drug resistance and, therefore, HIV treatment failure.

To fill these gaps in treatment, researchers are investigating:

• New and better HIV drugs for the treatment of heavily treatment-experienced adults with multi-drug resistant HIV infections.

• Improvement and wider availability of long-acting antiretroviral therapy, the latest innovation in HIV treatment medication (usually requiring two injections every 1 or 2 months, instead of pills every day).

• Development of new formulations of long-acting antiretroviral therapy with an autoinjector device that makes it easy and safe for patients to inject the drug themselves at home, most likely under the skin. Researchers hope that this method will increase privacy and medication adherence.

• Development of new versions of long-acting antiretroviral drugs as an “ultra-long-acting treatment and prevention” that could be injected every four months, and ultimately every six months by the end of the decade.

HIV researchers are also studying investigational vaccines to prevent HIV and treat HIV. The goal of a preventive HIV vaccine is to prevent HIV in people who do not have HIV but who may be exposed to the virus. A safe and effective HIV treatment vaccine (also called a therapeutic HIV vaccine) could prevent HIV from advancing to acquired immunodeficiency syndrome (AIDS), replace the daily use of HIV medicines, and help prevent HIV transmission. 

To learn more, read the HIVinfo What is a Preventive HIV Vaccine? and What is a Therapeutic HIV Vaccine? fact sheets.

Clinical trials are conducted in phases. Each phase has a different purpose and helps researchers answer different questions about the investigational drug.

• Phase 1 trial: Initial testing in a small group of people (20–80) to evaluate the drug’s safety and to identify side effects. At this point, researchers also look for signs that the new drug or treatment is effective.
• Phase 2 trial: Testing in a larger group of people (100–300) to determine the drug’s effectiveness and to further evaluate its safety.

• Phase 3 trial: Continued testing in large groups of people (1,000–3,000) to confirm the drug’s effectiveness, monitor side effects, compare it with standard or equivalent treatments (to see if it is better than current medicines), and collect information to ensure that the investigational drug can be used safely.

  In most cases, an investigational drug must be proven effective and must show continued safety in a Phase 3 clinical trial to be considered for approval by the FDA for sale in the United States. (However, some drugs go through the FDA’s accelerated approval process and are approved before a Phase 3 clinical trial is complete.)

• Phase 4 trial: Ongoing tracking that occurs after a drug is approved by the FDA for sale in the United States. The purpose of the tracking is to seek more information about the drug’s risks, benefits, and optimal use.

For more information, read the HIVinfo HIV and AIDS Clinical Trials fact sheet.

There are several ways to find an HIV and AIDS clinical trial that is searching for volunteer participants.

• To find an HIV and AIDS clinical trial that is studying an investigational HIV drug, use the find a study search feature on ClinicalTrials.gov.

• For help with your search, call a Clinicalinfo health information specialist at 1-800-448-0440 or email HIVinfo@NIH.gov.

• You can also join ResearchMatch, which is a free, secure online tool that makes it easier for the public to become involved in clinical trials. 

In some cases, an investigational HIV drug may be available through an expanded access program (sometimes called “compassionate use”). Expanded access allows for the use of an investigational drug outside of a clinical trial to treat a person who has a serious or immediate life-threatening disease and who has no FDA-approved treatment options. Drug companies must have permission from the FDA to make an investigational drug available for expanded access. must have permission from the FDA to make an investigational drug available for expanded access.

People seeking expanded access to an investigational HIV drug should talk to their health care provider to see if they may qualify to take part in an expanded access program.

One goal of HIV research is to identify safer, more effective HIV medicines. Researchers try to make clinical trials as safe as possible. However, taking an investigational HIV drug can involve both benefits and risks. Risks may include unexpected side effects from the drug, which can be unpleasant, serious, or even life-threatening.

The benefits and possible risks of participating in a clinical trial or an expanded access program are explained to people before they decide whether to participate through a process called “informed consent.” The informed consent process involves disclosing to potential research participants all the information needed to make an informed decision about whether to participate in the clinical trial.

To find more information on an investigational HIV drug, use the Clinicalinfo Drug Database, which includes up-to-date information on many investigational HIV drugs.

From the National Institutes of Health (NIH):

• NIH Clinical Research Trials and You: The Basics

• NIH Clinical Research Trials and You: Finding a Clinical Trial

From the National Institute of Allergy and Infectious Diseases:

• HIV/AIDS

From the U.S. Food and Drug Administration (FDA):

• Understanding Investigational Drugs

• Expanded Access | Information for Patients

Also see the HIV Source collection of HIV links and resources.