CrookedGrin78 t1_jeftrgg wrote on March 31, 2023 at 6:24 PM

Reply to comment by d0rf47 in ELI5: If benzodiazepines are CNS depressants, why is it so hard to die from a overdose of them alone? by psychrolute

Ah, but that sounds different from what other posters were saying, i.e., that combining certain CNS depressants is _worse_ than overdosing on either of them on their own, because they act on _different_ systems. So with GHB and alcohol, is that actually the case? Does one of them depress respiration and the other one does not? Or when people overdose on a combination of GHB and alcohol, is it just that they took a full dose of both and the combination was the same as it would have been if they had taken that big of an overdose of either one?

To put it another way, with certain combinations, it seems like the sum is greater than the whole of the parts (2+2=5), because Drug B is causing Drug A to create an effect that Drug A wouldn't create on its own, even if you overdosed on it.

d0rf47 t1_jefzmsx wrote on March 31, 2023 at 7:03 PM

its likely that the effects of one are potentiating the effects of the other. The bigger issue is a persons response to the drug and how their body metabolizes it. I am not a physician just some with a keen interest in pharmacology. CNS is your central nervous system, this system control much more than just breathing, certain drugs may affect the heart more while others affect the breathing more. the issue becomes troubling when the cns is suppressed enough that one of sub systems (breathing or heart) becomes so low that it either stop functioning and arrest begins or in some cases it may be that they are both still "functioning" but not properly and hypoxia can set in. My understanding with GHB and alcohol is that its the heart rate dropping which causes the dangerous effect.

Nagi21 t1_jegs3ew wrote on March 31, 2023 at 10:17 PM

You’re using the wrong math idea. It’s not 3+3=7, it’s 3*3=9

CrookedGrin78 t1_jefu36k wrote on March 31, 2023 at 6:26 PM

The kind of thing I'm describing is somewhat similar to combining an MAOI with a drug that's metabolized through a pathway that the MAOI suppresses: if you took either drug on its own, it wouldn't be a problem, but when you combine them, it's dangerous. I previously thought that a CNS depressant was a CNS depressant, but it sounds like that's not entirely true, since some CNS depressants inhibit respiration and some do not.