Patent protection for drugs hinges on protecting the molecules themselves in composition-of-matter patents. But its structure is only one aspect of a drug that can be protected by patents. Another possibility is to patent the chemical pathway to that structure via composition patents. Pathways, plural, actually – pretty much any compound can be synthesized via multiple routes. The patents around Merck & Co. Inc.'s Januvia (sitagliptin), for example, include more than 400 intermediates, and more than 450 unique reactions.