1g Pregabalin (Lyrica) - even much more so if taken without tolerance / buildup, which is what I guess from your post - is a high dose and as far as I know the mode of action of acute, high-dose pregabaline is not yet known - the substance features a "high" starting at maybe as low as 400mg w/o tolerance, which becomes more pronounced as dose escalates, that is quite unique and happens only if one has been off the substance for at least .. maybe 2-3 weeks, if not more. If one builds up slowly to 600mg/d as recommended, he will not trigger that - neither will taking 1.2g do when one is at 400 or 600mg/d.
A really odd substance. I would not be too surprised if it will show up that pregabaline is able to trigger a yet unknown receptor / mechanism ... like the GHB receptor...