Tamiflu is a modern antiviral drug lincenced for the treatment of influenza within the first 48hours of symptoms appearing. Tamiflu or oseltamivir phosphate is manufactured as 75mg oral tablets by Roch pharmaceuticals. The chemical structure is shown bellow:
Oseltamivir phosphate is a prodrug which requires metabolism into the active molecule in this case the carboxylate of the molecule shown, this can be achieved by esterification by enzymes found primarily in the liver. The mechanism of action will be discussed in the next section. Currently the product licence belongs to Roch pharmaceuticals. Roch are the sole manufactures of the drug to date, Although if in the case of a serious influenza pandemic the world health organisation can opt to lift this licence allowing other companies to produce the drug (Such a move has never before been invoked but in the light of the limited supply of tamiflu and the outbreak of avian bird flu such a move could be taken in the future.) The limited supply of Tamiflu is due to the difficulty of the synthesis of this drug, The current method used involves explosive azides as intermediates in two of the steps, also the starting materials are not readily available and cost of manufacture is high. This limited supply has lead many countries and in some cases individuals to start stockpiling the drug for emergency use.
The current synthesis is shown systematically bellow:
Alternative methods of production have been proposed recently, but very little information is currently available.
Click on the images below to view the interactive 3D structure of Tamiflu.