Why SN preferred to cardiac drugs

[pcm733]

The cardiac drugs are listed in PPH as similar to SN and aren't too hard to get(?); any sense of why SN is so strongly preferred?

 

[bb142342]

Which heart medications would those be? I must have missed that part.

Perhaps it's because they have to be taken in large quantities—and surely in combination with something else—since otherwise, the end would likely be agonizing, much like a heart attack?

With SN, the idea is supposedly that you keep breathing normally, but eventually the body can no longer absorb oxygen, and then you lose consciousness.