Granite Geek: Narcan Not Exactly the "EpiPen of Heroin"

Sep 2, 2015

Narcan (naloxone hydrochloride injection, USP) is an opioid antagonist.
Credit PunchingJudy via Flickr CC /

 Lawmakers and Governor Maggie Hassan supported legislation this year to make Narcan more accessible so it can be used to save the lives of people experiencing an opiate overdose. Narcan has often been referred to as the Epipen of heroin, but David Brooks says that comparison doesn’t hold up in some key ways. Brooks is a reporter for The Concord Monitor and blogs at He spoke with NHPR's Peter Biello.

David, before we get to the differences between the EpiPen and the drug epinephrine, which is used for allergic reactions, and Narcan, tell us how they’re similar.

From the layman’s point of view, they seem to do kind of the same thing. They’re both medicines that you give that very quickly stop a bad reaction that a person is having. EpiPen is actually the name for the mechanism that delivers a shot of epinephrine, or adrenaline, to someone who is having an allergic reaction to food. And it can almost instantly bring them back, especially if they’re having trouble breathing. Narcan—the generic name is naloxone—the medication overcomes the problems that are caused by an opiate overdose of things like heroin. Once again, it can make you stop breathing.

But as you write, that analogy of Narcan being the Epipen of heroin overdoses breaks down. And that has to do with the way Narcan and Epinephrine work. How do these two drugs work?

Narcan and naloxone is a replacement. It replaces the heroin in your brain cells, basically. The analogy is “lock and key.” If you think of your brain cells as having holes, the opioid comes along and fits like a key in a lock, and it causes your brain cell to do bad things. Well, the naloxone comes along and replaces the heroin. It can knock it out, or it can fill the hole before the heroin comes along, and prevents the connection from being made, prevents the opioid from causing your brain cells to do bad things. Whereas epinephrine, by contrast, does not affect what is happening when you have an allergic reaction. What it does is, it counter-balances many of the negative effects of it. It causes your heart to speed up and it causes your airways to open up and it does certain other chemical things, but it doesn’t affect the underlying mechanism, whereas the Narcan is a replacement. It replaces the underlying effect right at the very start.

You also write that volume matters for Narcan but not necessarily for epinephrine.

Certainly less for epinephrine. Narcan—particularly because Dr. Doris Lotz told me—this is really where the analogy can be dangerous. Narcan wears off and because it’s a replacement drug, when it wears off, the heroin, if it’s still in your system, the opioid, if it’s still in your system, can re-affect you, so it’s still floating around and the key and lock holes in your brain cell become available, the opioid will slip into them. So you can give Narcan and then be fine for a half an hour or so, but then you’ll relapse. That’s less likely to happen with an EpiPen, because it’s not affecting the mechanism, it’s stopping the bad effects. So if you give Narcan and think, “I’m okay,” and walk away, that can be really dangerous.

And it’s also not holding up when we consider naloxone versus epinephrine as a preventative medicine.

That’s right. Naloxone can be used as a preventative, usually in conjunction with other drugs, and it’s often given to addicts to help them wean from it, whereas epinephrine is not a preventative. You can’t give it before you go out to the beehive just in case. That would be a very bad idea, because it can have an effect on your system.

One big takeaway from this, David, is that analogies, when it comes to science and medicine, don’t always hold up.

Yeah, analogies are valuable for laymen like us. We absolutely have to have them to make us understand things. The problem is when you take analogy that works in one circumstance and assume it works in all circumstances. The example I like to give is “crystal medicine” or “crystal therapy.” What happens is, it's an analogy that human emotions are kind of like vibrations. You can use that analogy in certain ways, but people say, “Well, crystals can channel vibrations because of the latticework of the molecules, and therefore crystals can channel human emotions.” The next thing you know, you’re spending $100 on crystal therapy and that’s because you’ve taken the analogy way too far.

My big takeaway from this, David, is: question analogies.

Question analogies. I’ve never seen that bumper sticker but I’ll go make one immediately.