WEDNESDAY, Feb. 28, 2007 (HealthDay News) -- A commonly used hepatitis drug spurs resistance to HIV drugs in patients who are infected with both viruses, Johns Hopkins researchers report.
Although many medications have this problem, entecavir (Baraclude) was thought to be different.
"What that means is that [hepatitis B] patients, if they don't know they're HIV-positive, could start spreading drug-resistant HIV to other people," said Dr. Michael Horberg, director of HIV/AIDS policy at Kaiser Permanente Health Plan in Santa Clara, Calif. "And, once they are treated for HIV, it'll be harder to treat."
"We've always said that patients who are going to be treated for hepatitis B should be screened for HIV, even if they deny risk factors," Horberg added. "And, if they're co-infected, they probably should be treated for HIV as well, or at least be aware that they run the potential risk of creating a resistant virus."
However, Horberg did point out that the research comes from a tiny sample, only two patients. "Let's not draw conclusions based on only two patients, although it certainly is suggestive," he cautioned. "This small sample seems to lead to the question, 'Is it different?' "
The researchers, who are expected to present their findings Wednesday at the 2007 Conference on Retroviruses and Opportunistic Infections in Los Angeles, have already informed the U.S. Food and Drug Administration so prescribing physicians can be notified and drug labeling changed. They have also notified Baraclude's maker, Bristol-Myers Squibb.
"It gives you fewer choices in which to treat co-infected patients whose HIV doesn't need therapy yet," explained senior study author Dr. Chloe Thio, an associate professor of medicine at Johns Hopkins University School of Medicine. "The guidelines recommend entecavir as first-line therapy in HIV-infected patients who need their hepatitis B treated but not their HIV. That's no longer the case. With the data at present, the guidelines should be changed."
As many as 400 million people worldwide are infected with hepatitis B, a viral infection that affects the liver. For most adults, the infection is acute and lasts no more than six months. But for about 10 percent of adults, up to half of all children, and about 90 percent of babies infected with hepatitis B, the disease becomes chronic and can lead to scarring of the liver, liver cancer and liver failure.
Entecavir first came on the market in March 2005 to treat chronic forms of hepatitis B. Currently, the drug's label says it has no clinical effect on HIV. Recent research also had found entecavir to be more effective than another commonly used drug in managing the liver disease. A hepatitis vaccine has been available since 1982, but there were 60,000 new infections in the United States in 2004 alone. Currently, 1.2 million Americans have hepatitis B.
But, after seeing reports of anti-HIV activity in two co-infected patients, Thio decided to conduct an investigation on her own. (There has since been a third case.)
Thio and her team combined different concentrations of entecavir with 100,000 healthy human immune cells, then infected them with HIV and measured the number of cells infected over time.
In concentrations less than one-tenth of what is used in humans, entecavir slashed the number of newly infected cells in half (meaning that it slowed HIV replication). But higher concentrations of the drug brought no greater impact.
And the drug did not stop a mutated form of the virus (M184V) from infecting healthy immune cells, indicating that the drug contributes to development of this mutation. This was later confirmed in clinical testing.
More information
To learn more about hepatitis B, visit the Hepatitis B Foundation.
