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| |  Norvir Cleared by FDA for Treatment of HIV Infections ABBOTT PARK, Ill., March 1, 1996 -- The U.S. Food and Drug Administration (FDA) has cleared for marketing Abbott's (NYSE: ABT) HIV protease inhibitor Norvir (ritonavir) in combination with nucleoside analogues or as monotherapy to treat human immunodeficiency virus (HIV) infection in patients where therapy is warranted. For patients with advanced HIV, this indication is based on the results of a study that showed a reduction in both mortality and AIDS-defining clinical events for patients who received Norvir. Median duration of follow-up in this study was six months. The clinical benefit from Norvir therapy for longer periods of treatment is unknown. For patients with less advanced disease, this indication is based on changes of surrogate markers in patients receiving Norvir alone or in combination with other antiretroviral agents. Protease inhibitors are a new class of drug with a mechanism of action that is different from most of the previously available antiretroviral treatments for AIDS. Protease inhibitors, such as Norvir, block the action of protease, an enzyme involved in the final development of the virus. By blocking protease activity, protease inhibitors prevent production of infectious viral particles. "The data we have seen to date with Norvir offer new hope to AIDS patients," says Andre Pernet, Ph.D., vice president of pharmaceutical products research and development at Abbott Laboratories. "Now that this product is available, we have an important new tool which will help change the way this disease has been treated." In clearing Norvir for the treatment of HIV infection, the FDA reviewed efficacy and safety data from trials that showed the agent to have substantial antiviral activity and to reduce the risk of disease progression and mortality. This marks the fastest drug approval in the history of the FDA -- 72 days from the date of the filing of the new drug application. A randomized, double-blind, placebo-controlled study involving 1,090 patients with advanced AIDS and previous antiretroviral therapy was conducted at 67 investigational sites in the U.S., Canada, Europe and Australia. Norvir or placebo were added to baseline therapy, if any. A six-month analysis of this population showed that the cumulative mortality rate among Norvir patients was 5.8 percent -- approximately half of the 10.1 percent among patients receiving placebo. This six-month study depicts the first survival benefit demonstrated by a protease inhibitor. The clinical benefit of Norvir treatment for periods longer than six months is unknown. In a subset of 211 patients, statistically significant increases in the average CD4 count from baseline were observed with Norvir over the first 16 weeks of the study. The CD4 count was not significantly changed in the placebo group. In a subset of 159 patients, Norvir produced statistically significant decreases in average HIV RNA levels compared to placebo. Measurement of viral RNA is an indicator of the amount of HIV in a patient's blood. The clinical significance of HIV RNA is unknown. A second, ongoing trial is testing Norvir alone, AZT alone, and the two agents in combination in 356 patients randomized to one of the three treatment groups. These patients had not been treated with antiretroviral drugs. Norvir and the combination group produced statistically significant decreases in mean average viral RNA levels compared with AZT. Furthermore, statistically significant mean average increases in CD4 count were observed at 16 weeks with both arms compared to AZT. Additionally, in an open-label, triple combination trial involving 32 patients, combination therapy involving Norvir and the nucleoside analogues AZT and ddC nearly doubled the median CD4 cell count from baseline. The triple therapy also caused reductions in the number of HIV RNA particles in the blood by week 20. Norvir had a favorable safety profile in clinical trials. The most common adverse events were nausea (23% to 26%), diarrhea (13% to 18%), vomiting (13% to 15%), asthenia (9% to 14%), taste disturbance (5% to 10%), anorexia (1% to 6%), paresthesias (3% to 6%), and abdominal pain (3% to 7%). Norvir should not be used in combination with many highly metabolized medications known to produce serious or life-threatening adverse events. Specific information is available in the prescribing information. Eleven years ago today Abbott received clearance from the FDA to market the world's first HIV test. Abbott Laboratories is a worldwide manufacturer of health care products, employing 50,000 people worldwide. The company researches, develops, and markets pharmaceutical, diagnostic, nutritional and hospital products.
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