If you have never used it before my approach is cut the max dose in half and run half for the full cycle, keeps possible sides down and will yeild a more productive cycle, next cycle run 50mg or if 25mg works no need to change it, guys forget its not black and white, like for me, most say 500mg primo or a little higher, i run my primo at 300-400mg and i respond excellent, so i dont change it.