Nearly half of all HIV-infected patients in the United States develop resistance to one or more of their medications, experts say, making the epidemic of drug resistance a growing concern.
"Unlike other chronic illnesses, HIV is unforgiving," said Dr. John G. Bartlett, an expert in infectious diseases and professor at Johns Hopkins School of Medicine, speaking at an American Medical Association briefing. "Once the virus becomes resistant to one drug, we can never use that drug again. The challenge for physicians is to stay ahead of the virus with new drugs and newly available combinations of drugs."
There are various reasons for the development of such resistance. One key is that when patients either miss or skip a dose of their medication, it gives the virus a chance to multiply and mutate, allowing it to grow increasingly resistant to the drugs designed to fight it.
"As the virus mutates, the drugs lose their ability to prevent the virus from reproducing," Bartlett said. "The drug-resistant virus reproduces unchecked and the viral load [amount of virus] in the body increases."
In fact, a new study published in the Feb. 1, 2005, issue of the Journal of Infectious Diseases showed that adherence to the medication regimen had by far the greatest impact on the development of resistance. Patients who missed less than 5 percent of their medications did not develop resistance over the course of the 30-month study.
"Adherence is not just swallowing pills, but swallowing them at the correct times and with the appropriate dietary requirements," Bartlett said.
"A treatment goal for physicians is to find simpler drug regimens that can be taken less frequently to make it easier for their patients to follow their treatment plans," said Dr. Kimberly Y. Smith, assistant professor of medicine at Rush University Medical Center in Chicago.
"The trend has become using fewer pills with less frequent dosages," Smith said. "Although the ideal regimen would be one pill per day, regimens that include two to four pills per day are currently very popular and seem to be well-tolerated."
New laboratory tests also have been developed that help predict which medications may become resistant at some point.
"It's not easy to stay ahead of HIV," said Dr. Daniel Kuritzkes, associate professor of medicine at Harvard Medical School and director of AIDS Research at Brigham and Women's Hospital in Boston. "Resistance testing, at the beginning of treatment and as treatment continues, is one way we have devised to do just that."
For more information about drug resistance in the treatment of HIV, visit the American Medical Association's Web site at www.ama-assn.org. -NU |
|
