Important note: Information in this article was accurate in May 2002. The state of the art may have changed since the publication date. 
The 3rd International Workshop on Clinical Pharmacology of HIV Therapy was held 11- 13 April 2002, in Washington, DC. At this meeting, researchers from Europe and North America gathered to mostly present and exchange information about how some anti-HIV drugs, when taken together, can affect levels of one another in the blood. This effect is something that occurs when certain anti-HIV drugs — protease inhibitors and non-nukes (non-nucleoside reverse transcriptase inhibitors, or NNRTIs) — are taken.
In the mid-to-late 1990s, when protease inhibitors (PIs) were first released in North America, researchers found that when one PI called ritonavir (Norvir) was taken with another PI, saquinavir (Invirase), ritonavir boosted saquinavir levels in the blood much higher than when saquinavir was taken without ritonavir. Researchers also found that not only did ritonavir boost saquinavir levels, it also prolonged the time that saquinavir levels remained high. This discovery resulted in people with HIV/AIDS (PHAs) being able to take their saquinavir boosted with ritonavir only twice daily rather than three times a day. Similarly, PHAs who take other ritonavir-boosted regimens are usually only required to take their PIs twice daily. Ritonavir is now used to boost other PIs including the following:
A new PI called atazanavir (BMS-232632, Zrivada, or simply "Taz"), which is still in clinical trials, is also being tested both by itself and as a booster for saquinavir.
While boosted-PI regimens can be beneficial and convenient for some PHAs, they also have their problems. Some PHAs may find it difficult to tolerate large doses of ritonavir. This drug, and likely other PIs, may increase levels of cholesterol and triglycerides in the blood of some users, increasing the risk of developing heart disease. As PI levels in the blood increase because of boosting, other side effects may appear or pre-existing side effects may grow worse. To reduce some of these difficulties, researchers are testing other drugs which also have the potential to be used as PI boosters, including the non-nuke delavirdine (Rescriptor) and the anti-ulcer drug Tagamet (cimetidine).
Upcoming CATIE News stories will highlight selected reports presented at this pharmacology workshop.
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Copyright © 2002 - TreatmentUpdate. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Editor, The Canadian AIDS Treatment Information Exchange, 555 Richmond St. West, Suite 505, Box 1104, Toronto, ON, M5V 3B1 • Phone: 416-203-7122 • Toll Free: 1-800-263-1638 • Fax: 416-203-8284 http://www.catie.ca
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