Periactin,
it takes a couple of weeks to get used to. The tabs come in 4mg tabs and I usually took 3-6 before bed depending on my goals.
It's something that you have to build up to so I might even start at half a tab per day for the first 3-4 days. Then build up to 1 tab and again up from there. Most people become very lethargic while using it but I didn't have that problem. The biggest problem was waking up in the middle of the night with hunger pains and looking for something to eat and then going back to bed. I used it as an appetite stimulant, not as a "smart drug"