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Pronunciation(s): veye-KRIH-ver-rock
What is vicriviroc?
Vicriviroc is an experimental entry inhibitor developed by the Schering-Plough Research Institute. Vicriviroc is also sometimes called SCH-D, its former code name.
Vicriviroc binds to a protein on the membrane of T-cells called CCR5. Once it does this, HIV cannot successfully bind with the surface of T-cells, thus preventing the virus from infecting healthy cells.
Vicriviroc is believed to be more powerful than SCH-C, Schering-Plough's first entry inhibitor that is no longer in development.
Vicriviroc will most likely need to be used in combination with other anti-HIV drugs.
What is already known about vicriviroc?
A dose for vicriviroc has not yet been determined. Vicriviroc is being studied in a pill form, which means that it can be taken by mouth. Vicriviroc will only need to be taken once a day.
Vicriviroc will likely be active against HIV that is resistant to other entry inhibitors, including Fuzeon (T-20).
Vicriviroc might interact with other medications, including those used to treat HIV. Studies have already indicated that the PI Norvir (ritonavir) can increase vicriviroc levels in the bloodstream by 500% (Kaletra can have the same effect). The NNRTI Sustiva (efavirenz) can decrease vicriviroc levels by 80%, although this can be corrected by adding Norvir.
It is important that your personal physician and/or the research nurse or study investigator be aware of all drugs you are taking, including those you buy without a prescription.
What do we know about vicriviroc from clinical trials?
In one small phase I study conducted by Schering-Plough, HIV-positive patients who had more than 250 CD4 cells (T-cells) took either 10mg, 25mg, or 50mg vicriviroc twice a day for two weeks, without any other anti-HIV drugs. After two weeks of treatment, the study volunteers who took 10mg vicriviroc twice a day saw their HIV viral load decrease by 1.08 log, study volunteers who took 25mg vicriviroc twice a day saw their viral load decreased by 1.56 log, and those who took 50mg vicriviroc twice a day saw their viral load decrease 1.62 log.
In October, the manufacturer stopped a phase II clinical trial of vicriviroc involving treatment-naive patients (HIV-positive people who had not taken other anti-HIV drugs in the past). The study compared patients taking vicriviroc plus Combivir (AZT + 3TC) to patients taking Sustiva (efavirenz) plus Combivir. While viral loads dropped significantly in all of the study participants, those taking vicriviroc were much more likely to see their viral loads rebound during the study. After an average of 31 weeks, 4% of people taking Sustiva/Combivir saw their viral loads rebound, compared to 17% of people taking the highest dose of vicriviroc plus Combivir (rates of virologic failure were even higher among participants taking lower doses of vicriviroc plus Combivir). Clinical trials of vicriviroc in treatment-experienced HIV-positive people are still being conducted.
A phase II clinical trial (ACTG 5211) involving patients who had tried and failed other HIV treatments in the past (and were failing their current regimen) was reported in August 2006. Study participants were randomized to add one of three doses of vicriviroc (5mg, 10mg, or 15mg once a day) or a placebo to their current HIV drug regimen. After two weeks, participants continued vicriviroc, or placebo, and changed their other HIV drugs to an optimized background treatment (OBT) consisting of approved HIV medications that their virus may be sensitive to.
An independent study monitoring board reviewed the clinical trial for safety from time to time. At their review on October 6, 2005, the committee recommended stopping the 5mg vicriviroc dose because it wasn't working as well as the other doses. At their review on February 15, 2006, they noted five cancers in participants taking vicriviroc and recommended that all participants be told whether they were taking vicriviroc or not. At that time, 118 patients were enrolled in the study. The percentage of subjects with viral loads below 50 (undetectable) at week 24 was 7% in the placebo group, 40% in the 10mg vicriviroc group, and 27% in the 15mg vicriviroc group. In the placebo group, CD4 counts decreased by 6 cells, compared to a 142-cell increase in both vicriviroc groups. (Click here for more detailed results.)
Among those who remained in the study for a year, undetectable viral loads were seen in 37% of those in the 10mg group and 27% of those in the 15mg group by week 48 (click here for more detailed results). And in an open-label extension of the study, involving 39 patients receiving 15mg vicriviroc plus OBT, 60% maintained viral loads below 50 copies for up to two years of treatment (click here for more detailed results).
Phase III clinical trials for treatment-experienced patients are now being conducted.
What is known about side effects?
The side effects of vicriviroc have not yet been determined. Other than pulmonary tuberculosis in one patient, no opportunistic infections were documented during the ACTG study. There were no reports of liver toxicity or new cancers during the extended follow-up period.
Who should not take vicriviroc?
It is not known whether vicriviroc will harm an unborn baby. It is very important to treat HIV/AIDS during pregnancy to reduce the risk of infecting your baby. Talk to your doctor about your treatment options.
It is not known whether vicriviroc passes into breast milk and what effect it may have on a nursing baby. To prevent transmission of the virus to uninfected babies, it is recommended that HIV-positive mothers not breast-feed.
Where can I learn more about clinical trials of vicriviroc?
If you would like to find out if you are eligible for any clinical trials that include vicriviroc, there is an interactive web site run by ACRIA, the AIDS Community Research Initiative of America.
Another useful service for finding clinical trials is AIDSinfo.nih.gov, a site run by the U.S. National Institutes of Health. They have "health information specialists" you can talk to at their toll-free number at 1-800-HIV-0440 (1-800-448-0440).
Last Revised: October 04, 2007
This content is written by the editorial team at AIDSmeds.com.
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vicriviroc
belongs to a class of anti-HIV drugs called 
Check My Meds
Vicriviroc might interact with other medications, including those used to treat HIV. Studies have already indicated that the PI 
It is not known whether vicriviroc will harm an unborn baby. It is very important to treat HIV/AIDS during pregnancy to reduce the risk of infecting your baby. Talk to your doctor about your treatment options.
It is not known whether vicriviroc passes into breast milk and what effect it may have on a nursing baby. To prevent transmission of the virus to uninfected babies, it is recommended that HIV-positive mothers not breast-feed.