A Rise in Earnings?

By Econ70 | 06/15/2011

In the early ’90s Pfizer patented sildenafil to treat various heart-related conditions. That patent expires in ’12. During clinical trials men taking sildenafil experienced spontaneous erections. This led Pfizer to develop the same drug (Viagra) for ED. Pfizer then applied for a second patent on sildenafil as an ED drug. That patent ends in ’19.…

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