T 264/17 - Synthetic lubricant as a synovial fluid replacement

Art. 54(5) EPC provides for protecting the second or further medical indication for compounds which are otherwise (i.e., structurally) known. The proper claim format is the purpose-limited product claim format (e.g., "Compound X for use in medical method Y.", see G 2/08).

Traditionally the Boards have held that the  "substance or composition" of Art. 54(4) and (5) must be an "active agent or ingredient", in the sense of a pharmaceutically active agent. Chemicals which merely acted physically, such as injected collagen agents, were considered more a "device" rather than a "substance or composition" (see, e.g., T 1758/15). 

T 264/17 takes a different view on the issue.