This is from my personal experience.
It depends greatly on the manufacturer of the pill , you need to look up the ndc # and find out exactly what the ingredients are.
Water is the best solvent for morphine, followed by alcohol. You have to check with each ingredient in the pill if it will be dissolved with whatever solvent you choose.
Pretty much every pill will have fillers binders and excipients which will be dissolved with the morphine salt. The common are Hypromellose, Microcrystalline Cellulose, and lactose that will be extracted with the morphine.
The best extraction route is the cold water extraction, but it only works with certain brands. Others will gel up excessively due to the hpmc content and won't filter. These types require excessive preparation and require complete dissolution in aqueous acidic conditions for 12-24hr before attempting to isolate the morphine.
Isolation of morphine is as simple as raising the ph to 9-11 to precipitate the base, and then extraction by decanting, filtration, and washing the precipitate.
As for purifying the crude extract, the textbook method is recrystallization in anhydrous ethanol. I have not tried this personally.
I must admit it's not really worth the effort unless you have a lot of pills and patience. However the method of simply cold water extraction will get rid of a lot of the inert ingredients and then passing the solution through a .22um wheel filter, for the injection of morphine sulfate is useful for harm reduction purposes