The rise means Roche's global production network will be capable of producing 400m courses of Tamiflu annually by the end of 2006, a more than ten-fold increase since 2004.
The Swiss drug firm has predicted sales this year for Tamiflu will reach SFr1.1bn to SFr1.2bn (€7bn-€7.5bn), excluding sales as a treatment for regular influenza.
Amidst fears of a bird flu pandemic, the US Department of Health & Human Services (HHS) has been adamant that the US should be self-reliant in the supply of Tamiflu, so Roche and its external contractors have established all aspects of Tamiflu production in America, from synthesis of the initial starting material through all major steps of manufacturing to finished packs.
The initial starting material for Tamiflu is shikimic acid and is obtained in one of two ways; from the pods of the star anise in China or via a fermentation process.
The majority of shikimic acid used in Tamiflu today is derived by fermentation, reducing reliance on scarce natural sources and ensuring the US does not to depend on overseas resources.
To date the HHS has ordered 21.3m courses of Tamiflu for the US Strategic National Stockpile, which will be delivered in full this year.
The total targeted US stockpile is 81m antiviral treatment courses by the end of 2008 as the HHS plans to purchase 50m treatment courses and subsidise by 25 per cent the states' purchases of 31m courses.
"The ability to produce Tamiflu from start to finish on US soil is a significant milestone that will help ensure access to Tamiflu when and where it is needed," said Roche CEO George Abercrombie.
"This most recent expansion further demonstrates Roche's long term commitment to serving as a responsible and collaborative partner with the US government on pandemic preparedness and response."
Tamiflu is designed to be active against all clinically relevant influenza viruses, including the H5N1 virus, and has been shown to be active against the avian influenza virus in the laboratory and in animals infected with the H5N1 strain taken from humans.
Roche says it has received and is filling on schedule orders from more than 75 countries to date for stockpiling Tamiflu, and, thanks to more than 16 external contractors located in ten different countries, its capacity currently outstrips demand.
Albemarle, Ampac, API Corporation, Clariant, DSM, FIS, Martek Biosciences, Novasep/Dynamit Nobel, PHT International, PPG Industries, Sanofi-Aventis, Shaanxi Jiahe Phytochem and Siegfried are among the companies that are involved in the production of Tamiflu.
What is more, the company has granted sub-licenses to Shanghai Pharmaceutical Group and to HEC Group for the overall production of Tamiflu for pandemic use in China, as well as to India's Hetero Drugs to make oseltamivir for India and developing countries.
Roche has also reached an agreement with Aspen for providing Tamiflu for pandemic use to further help to address the needs of governments and other not-for-profit organizations in Africa.
In addition, Roche has donated a total of 5.1m Tamiflu treatment courses to the World Health Organization (WHO) for use as rapid stockpiles and regional stockpiles to respond to bird flu outbreaks.
Since 2003, 246 cases of bird flu have been reported in ten countries, costing the lives of 144 people.