Premarin was the first hormone replacement therapy (HRT) drug to hit the market. Premarin was first marketed in 1942 to alleviate the symptoms of menopause in women. Today, Premarin is still the most popular HRT drug, and is one of the most prescribed drugs in the world. There are approximately 11 million women currently take Premarin. The popularity of this drug is due both to its extensive history and an aggressive marketing campaign by Wyeth.