Patents are good for 20 years after the invention of a drug–not after the drug comes to market. It can easily take eight years for the pharmaceutical companies to gather enough data to get approval for their new invention from the U.S. Food and Drug Administration. Meanwhile the FDA can send the drug company back for more clinical studies (experiments using humans as subjects to test the drugs’ efficacy and side effects) and more data, and all the while the patent clock is ticking.
That’s why the name of the game for pharmaceutical companies is working to extend those patents for a top-selling drug
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