Well it would very likely have additional GABAergic effect, look at the difference in action between guiafenesin and methocarbamol (although I have tried large doses of both and both are utter fucking shit, to use the scientific terminology)
Methocarbamol is a muscle relaxant, albeit not a very good one, and certainly not a particularly recreational one, although it is useful with opiates for some potentiation, useful in the sense of if you have either nothing and opiates, or opiates and methocarbamol, I would opt for the latter, but guiafenesin is pretty much worthless.
That said, I haven't thought about it before just now, but this thread made me realise, there is a codeine OTC cough linctus with IIRC 7.5mg/ml or per 5ml I forget, called pulmo bailly in the UK, and its quite common, unlike codeine linctus, its branded and pharmacists here don't usually insist on an interrogation by an ex-member of the stasi secret police followed by x-rays and a cavity search before they will let you know if they have it in stock, let alone sell you any, and whats more, its kept in view on shelves so you can SEE if they sell it or not, preventing pharmacists from lying and telling one it isn't an item they carry.
Tastes HIDEOUS, like boiled wood shavings mixed with creosote and tannic acid, mixed with a generous helping of potassium aluminium sulfate, astringent as hell, but stench and taste of fence preservative aside, I noticed, thinking about it, that I usually go with it, even if its more expensive than codeine linctus, for at least one bottle, alongside the codeine linctus, or several on its own.
Contains 75mg/1ml or 5ml of guiaphenesin, and it does seem to be noticeably easier to end up with that warm glow and drooping eyelids than the equivalent of codeine phosphate liquid alone.
I'm going off track, gah, that what you get when I indulge in that ivory wave MDPV-mixture stuff and opiates, anyway, the carbamates do seem to have increased activity of their own.
I'm going to have the chance quite soon, to sample a novel carbamate derivative of 2-Me-2-BuOH, albeit one that has MDA attatched to the other end, but it SHOULD have some intrinsic activity of its own, before it hydrolyses into MDA and 2-Me-2-BuOH, although as some replying to my thread on it in this forum suggested, it may not last very long in that form, and may well not have such effects other than separate of the tert-pentanol and MDA due to rapid hydrolysis on contact with stomach acid.
I might as well try out the carbamate of tert-amyl alcohol itself though also, and contrast it with tert-amyl on its own.
Urethane sounds like its best left as its polymer in one's drywall insulation though.