What is an investigational drug?
An investigational drug is one that is under study and is not approved by the U.S. Food and Drug Administration (FDA) for sale in the United States. Medical research studies are conducted to evaluate the safety and effectiveness of an investigational drug. These research studies are also called clinical trials. Once an investigational drug has been proven safe and effective in clinical trials, FDA may approve the drug for sale in the United States.
What is racivir?
Racivir is an investigational drug for the treatment of HIV infection.
- Racivir is an investigational anti-HIV drug included in the nucleoside reverse transcriptase inhibitor (NRTI) drug class.
- NRTIs prevent HIV from replicating by blocking reverse transcriptase, an HIV enzyme. By preventing HIV from replicating, NRTIs reduce the amount of HIV in the blood.
- Racivir is similar in chemical structure to the FDA-approved NRTIs lamivudine (brand name: Epivir) and emtricitabine (brand name: Emtriva).
- In vitro studies have shown that racivir is active against hepatitis B virus (HBV).
How are clinical trials of investigational drugs conducted?
Clinical trials are conducted in “phases.” Each phase has a different purpose and helps researchers answer different questions.
- Phase I trials: Researchers test an investigational drug in a small group of people (20–80) for the first time. The purpose is to evaluate its safety and identify side effects.
- Phase II trials: The investigational drug is administered to a larger group of people (100–300) to determine its effectiveness and to further evaluate its safety.
- Phase III trials: The investigational drug is administered to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with standard or equivalent treatments, and collect information that will allow the investigational drug to be used safely.
An investigational drug must be proven safe and effective in a Phase III clinical trial to be considered for traditional approval by the FDA for sale in the United States. Some drugs go through the FDA’s accelerated approval process and are approved before a Phase III clinical trial is complete. After a drug is approved by the FDA and made available to the public, researchers track its safety in Phase IV trials to seek more information about the drug’s risks, benefits, and optimal use.
In what phase of testing is racivir?
Racivir has been studied in Phase II clinical trials.
What have recent studies shown about racivir?
In a Phase II study, racivir was compared with lamivudine in HIV-infected, treatment-experienced participants who had the M184V HIV mutation (a mutation associated with lamivudine drug resistance). Prior to the start of the trial, all participants were already taking lamivudine as part of a failing antiretroviral therapy (ART) regimen. Study participants were then randomly assigned to receive either racivir in place of lamivudine or to continue with lamivudine as part of their ART.
In this study, racivir was shown to decrease viral load in treatment-experienced adults who had the M184V resistance mutation and who had fewer than three thymidine analog mutations (HIV mutations associated with NRTI drug resistance). In terms of safety, no severe drug-related side effects occurred in either the racivir treatment arm or the lamivudine arm.
More information on Phase I and II testing of racivir is available from these sources:
- Racivir study results presented at the 14th Conference on Retroviruses and Opportunistic Infections, February 25–28, 2007:
- PubMed abstract:
Where can I get more information about clinical trials studying racivir?
More information about racivir-related research studies
is available from the AIDSinfo
database of ClinicalTrials.gov
study summaries. Click on the title of any trial in the list to see the ClinicalTrials.gov
trial summary and more information about the study.
I am interested in participating in a clinical trial of racivir. How can I find more information about participating in a clinical trial?
Clinical trials involve benefits and risks. Before deciding to participate in a clinical trial, talk to your health care provider. For more information on participating in clinical trials, visit NIH Clinical Research Trials and You.
Last Reviewed: November 2, 2012
Last Updated: November 2, 2012