There were a few threads on here where we discussed the possible mechanisms involve for drugs such as carisoprodol. I'll only go as far as to reiterate that carisoprodol may not be a mere prodrug for meprobamate. This hasty assumption has left us with very little data regarding the activity of carisoprodol. Having sampled meprobamate proper, I myself have found a rather distinct difference.
In regards to the 'convulsant' properties of carisoprodol, it is important to differentiate pro-convulsant actions from any tremor associated with ataxia. A similar sort of ataxia seen in carisoprodol intoxication also can also occur with subanesthetic doses of barbs, methaqualone, ethanol and GHB.
And surely, the action of the drug has been characterized as 'barb-like', but it is simplistic to describe it as an 'agonist'. Similarly, if its established that the drug acts in a 'barb-like' manner, why is it relevant to discuss its inability to be reversed by flumazenil?
But back to the question of carisoprodol as a potential pro-convulsant: This is admittedly a rather crude/incomplete explanation, but I am trying to drive at the moment. Basically, if I recall correctly, carisoprodol can at relatively high doses (such as single po doses of 1050mg) be self-limiting in respect to the degree of GABAa positive modulation/GABA potentiation (caused by signaling blockade-NMDA inhibition at high doses). Thus at a sufficiently high dose, GABAa positive modulation may be partially interrupted or limited, resulting in a 'hiccup' of sorts (as the concentration falls back over a rather short period of time, interruptions to GABAa + mod become less prevalent; a rebound if you will). Of course all of this is further complicated by the continued reuptake inhibition of adenosine, which may allow for continued somnolence during these periods. I must caution that direct binding can occur at massive doses resulting in coma (overdose etc). Compared to potent barbs and methaqualone, carisoprodol is relatively safe (emphasis on 'relative', as barbs and methaqualone-analogs are notoriously unsafe and unforgiving).
Again: this message was dictated and not reviewed. Officer: "Sir, why were you looking at your phone while driving?", reply: "I was trying to ensure that I was accurately describing the mechanism of carisoprodol's potential convulsant activity when abused, in an intriguing online discussion entitled 'Soma Shakes'".......