“Relates a product (typically medicine) to a substance which it contains as an ingredient. Ingredients can be specified for medicines or other products, including devices, but they always mean the same thing: a material (here: chemical substance) in the make-up of the main product, not a structural part or content of a container, and not a material added later into a device for operation. For medicines and food this is obvious. For devices, an example for ingredient would be latex in a chest tube (but not an inhalant in a nebulizer device).” – HL7 Version 3 (Role->Ingredient). "Identifies a particular constituent of interest in the product." - HL7 FHIR, Medication.ingredient