Hugh,
I work for a large drug manufacturer and have spent 22 years as an analytical chemist testing and evaluating the stability of active pharmaceutical ingredients.
Medicines, except liquids, should be stored in the freezer. Liquids should be stored in the refrigerator or as cool as possible. Store the non-liquid medicine in its bottle in a plastic bag with desiccant inside. The worst enemies of drug products and active pharmaceutical ingredients (APIs) are temperature and humidity. The higher the temperature and humidity the faster your medicine will deteriorate. The longest drug stability times are associated with freezer conditions and low humidity. – J.P.