Viagra was approved by the Pfizer first on 1989 . American scientists working for Pfizer first created the drug in March 27 , 1998 . Since then 2000 major competitors for Viagra have been approved .
Viagra was approved by the FDA on March 27 , 1998 . British scientists working for Pfizer first created the drug in 1989 . Since then three major competitors for Viagra have been approved .