Just a little history lesson from an old guy ...
Pre-AIDS poppers were indeed amyl nitrate and it's a medication that's used for people with heart problems, I believe. Before AIDS was AIDS, in the very beginning, it was called Gay Related Immune Disorder (GRID). At that time, the scientific community was looking for a link between gay men and this disease. Poppers seemed a natural link. So, in order to stop the spread of the disease many governments banned the sale of amyl nitrate. The manufacturers of the stuff just rejigged the chemical configuration so that they weren't selling amyl nitrate but perhaps butal amyl nitrate. And so the game of cat and mouse went. God knows what the chemical configuration of the stuff is now.
Cheers,
Michael