I have 2 of the big black storage boxes from B&Q, on yellow wheels. They are lockable so fine to store meds in too. I have a big one for all my sheep drenches and pour ons that is locked with 2 padlocks, and a slightly smaller one with all my lambing stuff, marker crayons, tupping harnesses, odds and ends. All of our injectable meds are kept in a cabinet on the wall but there's no reason they couldn't be kept in a box like this too, with a lock on of course.