The following drug information is obtained from various newswires, published
medical journal articles, and medical conference presentations.
Approved on December 7, 1995
The first protease inhibitor approved by the FDA, saquinavir is
part of a new class of drugs for the treatment of advanced HIV
infection. Saquinavir received approval for use in combination with
older nucleoside analogue medications only three months after the
FDA received the application for its marketing.
The FDA based its approval of saquinavir on clinical trials
comparing three drug combinations in more than 900 HIV-infected
individuals: saquinavir with AZT, saquinavir with ddC, and
saquinavir with both AZT and ddC. The primary measure of drug
effect was changes in patients’ CD4 cell counts, an indication of
immune system strength. Values greater than 800 per milliliter of
blood are normal in healthy individuals.
Over 16 weeks of treatment, CD4 cell counts increased an average
of 30-40 cells per milliliter in subjects on saquinavir in
combination with ddC, AZT or AZT plus ddC. Effects were
attributable to combinations of saquinavir and a nucleoside
analogue to which a subject had not been previously exposed.
Saquinavir doses of less than 600 mg three times a day did not
produce increases in CD4 cell counts. The duration of CD4 cell
increases is not fully determined, although in general the increase
lasted for at least the 16 weeks of the trials.
Saquinavir was granted as an accelerated approval, a regulatory
mechanism under which the agency bases early approval for a product
on laboratory markers such as CD4 cell counts, rather than on
clinical endpoints such as delay in death or reduction in
Few adverse effects were associated with saquinavir; most
patients tolerated the drug well.
Mechanism of Action
Both protease inhibitors and nucleoside analogues chemically
inhibit replication of the human immunodeficiency virus, although
at different points in the replication process. Nucleoside
analogues include the already-approved anti-HIV drugs AZT, ddC,
ddI, d4T and 3TC.