system
Given the following post, respond as if you're commenting on Reddit:
human
How does naloxone (Narcan) work so quickly?

Anecdotally, people who've used naloxone on someone who has overdosed on an opiate say that it wakes the patient up immediately.  The same thing was a plot point on [Insert Spoiler Show Name] recently: [Insert Character Name] had been given an overdose of heroin, and [Somebody Else] showed up to administer naloxone (intranasally) and [Character Name] woke up.

I understand that opiate overdoses often kill by depressing respiration and perhaps heart rate, so I wonder:

How does intranasal naloxone get where it needs to be, if respiration and circulation are slowed?  If respiration has stopped (but only recently), will naloxone still work?  What about circulation?
gpt
Naloxone is absorbed through the mucous membranes in your nose, if you give it intranasally. At a basic level, it has a higher affinity for opioid receptors than the opioids themselves, but has no action when it binds - it’s a classic antagonist. Because of its high affinity, it takes very low concentrations to achieve its effect in the presence of exogenous opioids. You don’t have to be breathing to get naloxone *per se,* since circulation is not dependent on respiration, but you do have to have circulation to absorb the drug from the mucosa and perfuse the brain. 

If you don’t have circulation, you have much larger problems on your hands, and we’re in the middle of coding you, hopefully. But opiates affect respiratory drive significantly more than they affect cardiac physiology.