A metal promotional ruler for Sharp & Dohme Canada. Since the medication name was registered in 1946, and the ruler proclaims "For more than six years", the item is most likely from the 50's.
Sharp & Dohme was established in Baltimore in 1860. New York-based Merck merged with Sharp & Dohme in 1955. In 1965, they acquired the Charles E. Frosst Company of Montreal. In 1982, they became Merck Frosst Canada. In 2009, they merged with competitor Schering-Plough in a $41 billion deal. Evidently, there's lots of money to be made from carefree eating!