AIDSWEEKLY Plus, 8 July 1996
Daniel J. DeNoon, Senior Editor

Ritonavir, Abbott's entry in the HIV protease-inhibitor sweepstakes, is highly effective in combination with other anti-HIV drugs.

The data described by senior Abbott researcher Akhter Molla is expected to be released during the July 1996 XI International Conference on AIDS in Vancouver, Canada.

Molla said that the combination of ritonavir with the less potent protease inhibitor saquinavir (Invirase, Roche) "holds great promise."

Molla described the studies during a presentation to the International Business Communications (IBC) workshop "HIV Protease Inhibitors," held June 11, 1996 in San Francisco, California.

Four dose combinations of ritonavir and saquinavir are being tested in a clinical trial that has enrolled 120 patients with HIV infection and CD4 counts of 100 to 500 cells/(micro)L.

"The data looks very promising," Molla said.

Ritonavir binds powerfully, but reversibly, to the liver cytochrome P450 3A (CYP3A), thereby inhibiting not only its own, but also the CYP-mediated metabolism of other, structurally diverse protease inhibitors. The drug thus greatly increases serum levels of saquinavir in a dose- dependent fashion.

Molla said that no liver toxicity has yet been seen in patients receiving the ritonavir/saquinavir combination.

In a smaller study, 32 HIV(+) patients with CD4 counts of 50 to 250 cells/(micro)L or with rapidly declining CD4 counts received ritonavir for two weeks followed by triple combination therapy with ritonavir, ddC (zalcitabine), and zidovudine (AZT).

After 36 weeks of treatment, the patients had a mean increase in CD4 counts of 140 cells/(micro)L. Sixty percent of the patients had their HIV RNA levels drop below the limit of detection (i.e., <200 copies/ml).

Molla said that ritonavir is currently being tested in combination with AZT and lamivudine (3TC).

960708
AW960702

Copyright © 1996 - Charles Henderson, Publisher. All rights Reserved. Permission to reproduce granted to AEGIS by Charles W. Henderson. Authorization to reproduce for personal use granted granted by C. W. Henderson, Publisher, provided that the fee of US$4.50 per copy, per page is paid directly to the Copyright Clearance Center, 27 Congress Street, Salem, Massachusetts 01970, USA.