Pentobarbital is barbiturate. It slows down the neurological activities of your brain and nervous system. Besides, it can be used as a short term sedative to treat insomnia; it will help you fall asleep for the surgery.
The onset of the action of the Nembutal varies between 20 to 60 minutes. For IM administration, the onset action is slightly faster; on the other hand, IV administration of pentobarbital sodium to 5 minutes.
You can easily buy pentobarbital without any difficulty on the internet. However, there is little awareness about the drug in the present time as medication for the assisted suicide, its demand among suicide attempters increase.