Protease Inhibitors in HIV Therapy
There are about 950,000 HIV carriers in the U.S. Of these, approximately 370,000 have been diagnosed as HIV-positive and are receiving treatment and 188,000 take at least one protease inhibitor. In Western Europe approximately 550,000 individuals are HIV positive with 85,000 taking a protease inhibitor. The protease inhibitor market is estimated to be $750 million in the U.S. and $1.2 billion worldwide.
The spread of AIDS in the underdeveloped world, particularly sub-Saharan Africa, is much more severe, growing to the point where the disease is becoming a destabilizing influence on the governments of badly affected countries. The National Intelligence Council (“NIC”) issued a report in September 2002 assessing the influence of the virus on the stability of five countries of strategic importance to the U.S., including Russia, India and China. The NIC estimates there will be 75 million to 100 million HIV carriers by 2010.
The introduction of drugs to inhibit the HIV protease has become an effective therapy for HIV/AIDS patients in the western world. However, it has been documented that there are numerous associated problems. Protease inhibitors reduce the patient viral load but do not eliminate the virus from the body. Therefore, a lifetime therapeutic regime is required. Protease inhibitors suffer from considerable degradation by CYP 3A and must be delivered at high concentration to effectively combat the virus. This results in a very high dosing and pill load for the patient. In order to achieve the maximum suppression of viral-replication, HIV patients are required to adhere to complex regimens often including three or more drugs. These regimens often consist of 20 or more pills daily, taken two or three times each day at strict intervals and each with their own ingestion protocol such as fasting or high-fat or high-protein meals. Protease inhibitors are a significant contributor to the complexity of such HIV regimens. The complexity of the regimens can be greatly simplified by boosting the protease inhibitor.
Protease Inhibitors in Hepatitis C and B Therapies
Severe oral bioavailability problems have been observed with several drug candidates in development for the treatment of Hepatitis C or B (“HCV” and “HBV”). These antiviral markets are expected to have similarity to HIV in that only the drugs that attain the highest concentrations will achieve acceptable efficacy and obtain lasting market share. The treatment of HCV and HBV are very large unmet medical needs. It is estimated that there are 170 million people worldwide infected by HCV with 4 million in the U.S. HCV infected individuals frequently have no symptoms and the disease is only diagnosed in about 35,000 patients per year in the U.S. However, it can lead to chronic hepatitis and progression to liver cirrhosis. The current mortality rate in the U.S. is 10,000 to 20,000 deaths related to HCV per year. Current interferon-based HCV therapies are expensive with extensive side-effects and only effective in 10% to 40% of patients. However, revenue for interferon-based HCV therapies exceeded $2 billion for 2006. HBV infects approximately 2 billion people worldwide of which 300 million are considered to be chronic carriers including 1 million in the U.S. Currently marketed products for HBV treatment are considered to be effective in only 30% of patients.
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