Drug levels and HIV

July 2001     View PDF     En español

Protein binding

It is widely known that anti-HIV drugs get bound to certain proteins in the body, which results in decreased anti-HIV activity. In some cases, this has resulted in the drug being pulled from development because it lost almost all of its activity. The more a drug is bound to these proteins, the greater the loss in anti-HIV activity.

The amount of these proteins is:

• higher in HIV-positive than HIV-negative individuals,
• lower among people with cirrhosis (a liver disease caused by the loss of functioning liver cells) as the liver produces these proteins,
• higher during periods of inflammation, and
• different between genders and among ethnicities.

This has been an area of intense debate among the pharmaceutical companies developing drugs because you can get very different results on anti-HIV activity depending on the amount of protein used in their lab experiments. As a result, each company claims that its drugs, at least in their labs, are more active against HIV compared to their competitors.