MS Contin is continuous release morphine sulfate manufactured by Purdue Pharma, which also makes the brand name Oxycontin.
I've never looked it up, but I've always assumed Purdue uses "contin" in both of those names as an abbreviation in reference to the continuous release dosing of the respective narcotic. In the case of MS Contin, it's M
uous release; for Oxycontin, it's Oxy
But like I said.. I've never researched that..