Carisoprodol, best viewed as a muscle relaxant AND mild barbituate?

[Nucynta_80]

Essentially as I understand it, Carisoprodol (CAR, commonly known as "Soma"), is basically a molecularly modified form of meprobamate. To my understanding roughly 1/2 of it turns into meprobamate over a 2 hour period. Additionally -

From Wiki: "It has been shown that meprobamate has the ability to activate currents even in the absence of GABA"

From Emed Expert "that it was acknowledged that carisoprodol was mostly metabolized to meprobamate in humans" and "The results of a double-blind study that compared carisoprodol, butabarbital, and placebo, have shown the effectiveness of carisoprodol in the treatment of the low back pain syndrome 4. Carisoprodol was found to be significantly more effective in providing both subjective pain relief and objective improvements in range of motion when evaluated by finger to floor testing. The results of this study suggest that the effects of carisoprodol are not secondary to its sedative effects alone, but are also related to its muscle relaxant activity."

it seems that its BOTH a muscle relaxant and a barbiturate. Would that be accurate? Does anyone know the exact metabolism rate (50% or greater to my understanding).

I am prescribed CAR in combination with Tapentadol (commonly known as Nucynta) as an adjuvant for pain along with meloxicam and lidocaine patches. This combination is actually fairly effective (thought thank God for insurance), enough so that I haven't changed or requested a change in formulation from my doctor in quite some time. I usually only take 1 to 2 CARs a day, though I can take up to 4 as needed (limiting to 2 a day has helped A LOT in keeping tolerance down). I was on cyclobenzaprine some time ago but found it difficult to take on a regular basis because of the lethargic high, so this has worked nearly as well but with less side effects in its place.

 

[sekio]

it seems that its BOTH a muscle relaxant and a barbiturate.

it's not a barbiturate because it's not derived from barbituric acid... that said it does produce effects exactly like barbs do
but barbiturates are muscle relaxants, i thought?

Does anyone know the exact metabolism rate (50% or greater to my understanding).

varies depending on personal physiology

 

[Burn it up]

Ah, good ol' carisoprodol. We don't have it any more here in the European Union. Enjoy it, but take care with tolerance. I would continue taking max 2 per day, and maybe even take just one the days that you're not feeling any pain. For how long will you follow this treatment?

And as sekio said, barbiturates are already muscle relaxants. Carisoprodol is not technically a barbiturate though it produces the same effects as they do, muscle relaxation being one of them.

 

[Hammilton]

That's too bad. It's one of my favorite drugs ever! Half a tablet significantly boosts the effects of buprenorphine. Makes it feel like a full agonist. Phenobarbital did the same, however, the dose of phenobarbital could be absolutely minuscule (5mg or less) each day, and the result would be the same. That was an interesting time in my life. However, it was super easy to go overboard and accidentally feel like shit.

I have to question whether it's truly identical in action to barbiturates, though. It lacks the narrow therapeutic index of the barbs, and doesn't seem to add respiratory depression at normal opioid doses. I'm sure you could take 5 Soma's and double your usual opioid dose and get an all expense paid to the morgue, but I don't see it as easy to do, unlike with phenobarbital and other barbs. Perhaps this is related to barbiturates AMPA-related effects.

You could never compare Carisoprodol to Phenobarbital, though. That would be ridiculous. Carisoprodol is an extremely fast hitting drug with a very short duration (sober to knocked-on-your-ass-high in 10-15 minutes to sober in another 120!). I used to take a 5 or 6, drive out to the woods, it'd kick in on my walk to my spot, then sit and call coyotes. I always brought a gun, but I never shot anything. I'd then sober up and head home. I realize this was stupid. At the time I thought Two and a Half Men was a good show, to put things in context.

I'm sure close to 100% is metabolized. It has a half life of 2 hours (this number is widely variable though, some report at long as 8 hours). Meprobamate has a half life of 11 though, I believe. It's not entirely metabolized to meprobamate, though, either.

 

[sekio]

If memory serves, carisoprodol/meprobamate has the dubious distinction of causing some very strange neurological effects (the "soma coma" as it were, seizures/tremor) that benzos/barbs don't really cause.

The "open chain barbs" are certainly odd children.

 

[Hammilton]

I don't think it actually causes seizure, I think it might lower the threshold some. In terms of tremor, I have noticed it, but only during the very initial stages of the drugs onset. It comes on so fast and strong that I always assumed it was just the "rush" that caused it.

Actually, when I was on selegiline + 175mg Diphenhydramine (daily) + Suboxone, I noticed a similar tremor during the diphenhydramine's onset, but which lasted slightly longer. Without selegiline it wasn't present, so it was probably related to Diph's monoamine reuptake capabilities. Whether carisoprodol has a similar mechanism is pure speculation, as I have nothing but similar subjective effects to link them.