I think most suicidal people want something a little faster-acting and less painful than acetaminophen, though, and the other listed drugs are more or less prescription only.
The advice of giving it a fictional name is good, but as the writer will probably be describing its effects as the character dies, it is better writing to have something specific in mind and disguise it with a fictional name. Otherwise, you could end up talking about something completely implausible, or listing symptoms that nothing could account for.
There was a show recently (Law & Order?) that had a Dr. Death-like character. He committed suicide on the witness stand by taking a bottle of propranolol (Inderal) an hour before. Slowed his heart down.
Anything in suppository form, as long as you’re writing a comedy.
While giving the drug a made up name isn’t a bad idea, as Le Ministre de l’au-delà said, I don’t want to come up with something that’s entirely implasuble, either.
I didn’t think to mention it this morning, but this character has also been an alcoholic for 40 years (never got over the loss of one of his kids) so he has the health issues that come with drowning your sorrows for that long, too.
Then, ISTM that you’d want to go with something that taxes the liver like Tylenol. What prescription drugs tax the liver?
You won’t get that rapid onset from any liver damage, it seems to me; what about nitroglycerin? Hypotension will kill quickly, if it kills at all.
Just about any antidepressant will work. And you know how we 60-somethings pop them like candy, to forget about the impending grim reaper on our heels.
How about an overdose of insulin, would that be possible ?
I agree with insulin. A big dose would give your diabetic character a few minutes to talk first, but not much…