For shorter periods of time, you could use the Lock and Lock containers. They are a thick yet forgiving plastic, with a rubber gasket and good snap closures on all 4 sides. I have a friend with RA and the same issues, I take him cured medicine in them and they work great for him. I painted the outside of the box with white Krylon spray paint to block any light should he forget to put it away and to keep prying eyes, blind. I merely give the meds to a few trusted and needy people. It is very humbling to help my one friend, his RA won't allow him to use a normal grinder, but he is proud of his little electric [battery] grinder.
Be good to others, someday we will be in their shoes