DDMP is a 4-drug protocol consisting of digoxin (25mg), diazepam (500mg), morphine sulphate (10g) and propranolol (2g). In Australia, most likely you'll need prescription for every one of them.
There is also a 3-drug protocol consisting of chloral hydrate (20g), morphine sulphate (3g) and phenobarbital (20g).
The 4-drug protocol is considered an improvement over the 3-drug one but both are lethal.