In the news ... 2006 archive

Encouraging Results from New Protease Inhibitor

December 15, 2006

Ambrilia Pharmaceuticals recently announced encouraging results from a phase I safety study of their protease inhibitor, PPL-100. Although nine protease inhibitors are currently approved, almost all of the widely used ones require a boosting dose of Norvir (ritonavir). Project Inform has been calling for drug companies to rethink using Norvir boosting because of its potential side effects. We welcome a new protease inhibitor that does not require it. (For a more detailed discussion of Norvir boosting, read this article.)

Phase I trials are small safety studies. This is usually the first time a new drug is taken by humans, so only a few people take it and only for a short time. The most important question answered by these studies is whether the drug is at all safe for humans to take. In this study, PPL-100 appeared safe and well tolerated with no serious side effects reported. However, this does not guarantee that the drug will be safe in long-term, continuous use. Other studies will continue to monitor the safety of the drug.

The scientists also tested how the drug was absorbed, distributed and eliminated from the body. This is called pharmacokinetics. While no specific results have been released from these tests, they are planning to study PPL-100 as a once- or twice-a-day drug- —again without the need for Norvir boosting.

This report follows the October announcement that Merck had secured the rights to develop PPL-100. The next step for this drug will be to move into Phase II studies, which will probably test several doses of the drugs, hoping to find the ideal dose for the largest number of people. Phase II studies are longer—usually several months, involve more people, and collect more meaningful information on side effects. Such studies will also begin to collect early data about the effectiveness of the PPL-100.

With over twenty drugs now available, the HIV pharmacy shelves may seem crowded to some. However there is still a need for new and better drugs to treat HIV. If it proves potent and well tolerated, PPL-100 could be an important step forward, particularly for people intolerant to Norvir or who prefer not to use it. Project Inform will continue to follow the development of this new drug carefully.