Are you serious? I just throw mine away in the bottles they came in. I had no idea you were supposed to do anything special to dispose of them. Not that I have so many old prescriptions, and only once in my life have I ever had one with a narcotic (codeine, if that's a narcotic) in it.
Does this only apply to oral meds (pills, liquids), or to topicals as well? I just threw out some expired prescription shampoo and skin cream.