We spoke with the Item Lead who brought up a few points about medicines.
Currently items were designed to be used sparingly, and as a result the re-use duration is set longer. We don't want to create a scenario where players are expected to regularly have a whole host of healing items taken to each activity, nor a situation where players in a healing or enhancing role would not be necessary solely because of items.

Food is designed with a different duration in mind specifically as well, because the concept of these items are quite different.