Besides, there is no need for a doctor.
yeah, its not like anyone has ever failed to kill themselves properly, or that a trained doctor would know how to dose people right to give them a peaceful, effective suicide.
I'm sure people who are in the mental state to want to kill themselves don't want to go through the ordeal of having to try twice.
There are numerous accounts of people trying to kill themselves using guns, only to be badly brain damaged and disfigured, but survived.
Also many people who opt for assisted suicide are paralyzed or disabled in a way to make suicide impossible without help, besides biting their tongue off and bleeding to death.. Funnily enough, not everyone's friends and relatives are up for the idea of killing a loved one, so having a doctor do it is a good alternative.
Its no more unethical for a doctor to help someone commit suicide than it is for a drugstore clerk to give someone meds to overdose on, or a gun smith to sell a gun to kill themselves.
If someone wants to end the misery of their life, then helping them is compassionate, not unethical.