How long to kill someone paralyzed/held?

How are physical attacks against paralyzed or magically held creatures resolved? The rules on magically slept creatures are clear, but not so for those who are paralyzed or held.

Is it one round of effort for someone not otherwise engaged as with the Sleep spell? Is it automatic hits and simply use the normal hit point system?

How about magical attacks that do damage and those that call for saving throws?

Thanks in advance for your answer.

We’ve been using full-round otherwise unengaged, as with magic sleep. We may have derived it unconsciously from the 3.x coup de grace rules, though; I don’t know if it’s actually in the rules anywhere.

All attacks on helpless creatures are handled like Sleep.

Thank you, Alex.