I have taken Dilantin for 63 years and my blood level has always been in the therapeutic range between 10-20. I usually I'm around 12 or13, I had my blood drawn last week and it was30 I take 300 grams twice a day. My doctor also told me to reduce the nighttime med to 200 and redraw my blood again in 2 weeks. just remember you can overdose on Dilantin and it's no fun