Im pretty sure what he is speaking of is meth because I seen a document and researched about dex they call it dex for short and even did the document I researched. So im almost 90% sure what your taking is a medical form of meth so dont take 500mg, take 100mg for high doseage depending on your tolerance and stomach and among other things but ur safe as long as u stay hydrated. I've done alot more than 400-500mg before but I wouldnt recommend you doing so. Around 100mg will mess you up but if you take them orally you wont feel the true "tweak/spun" out feeling people get off street meth when smoking or snorting. I suggest you to snort a accurate doseage of it and yes it will burn like the pits of hell.