No way dude. Overdosing on medication is the most unreliable way to go. You would wind up immediately regretting it as soon as you swallowed the pills and going to the hospital. After that? They will most likely be able to save you, but you will wind up with liver, kidney, and possibly brain damage.
If you are truly intent on killing yourself, use a gun through the roof of the mouth. If you can, use a 12 gauge shotgun with .00 or .000 buckshot. Put the barrel on the roof of your mouth, and tilt it back at a 45° angle towards your limbic system and brain stem. BANG! Instant death.
Warning: should be obvious, but this is not an attention seeking technique. That shit will fucking kill you dead.
To OP: I know it sucks right now, but you should really reconsider this. Your have only one chance in life. You should really weight in the pros and cons of committing suicide and whether or not you truly do want to stop existing.