The scope of protection of use-related product claims under Art. 54(5) is limited to the substance or composition in the context of its medical use which confers novelty and non-obviousness, if any, on the claimed product. Guidance on products which can be seen as "substances or compositions" in this context can be found in T 1758/15, which relates to a biocompatible filler material for use in a specific therapeutic method.
This principle applies only to substances and compositions and cannot be extended to other products. A claim directed to a device for an intended medical use (e.g. pacemaker or implantable chemical sensor for use in ...) must be construed as claiming a device which is suitable for that medical use (F‑IV, 4.13).
A product qualifies as a "substance or composition" in the sense of Art. 54(5) if it is the active agent or ingredient in the specific medical use and if the therapeutic effect can be ascribed to its chemical properties (see G 5/83 and T 1758/15). For example, consider a filler material which is injected between a first tissue targeted for radiation treatment and a second sensitive tissue which is desired to be protected from radiation. If the shielding effect of the filler material is achieved by a mere mechanical displacement of the sensitive tissue relative to the target tissue, due to the volume it occupies between the two tissues, the filler material qualifies as a device rather than a substance or composition. On the other hand, if the filler material produced a radiation-reducing effect on the sensitive tissue which could be attributed to its chemical properties, it would be considered as a "substance or composition" in the sense of Art. 54(5).