Metagenics and Standard Process are 2 brands that can only be purchased through health care practitioners, although there are others that can be found OTC. Pharmaceutical grade vitamins are made from pharmaceutical grade raw materials to pharmaceutical grade manufacturing standards in FDA registered facilities following the US Pharmocepia guidelines (USP) for dissolution of the capsule or tablet. You'll know you're buying a pharmaceutical grade supplement because there'll be a USP designation on the label.