Mirtazapine
"I was given 15 mg caplets and told to cut them in half.. 7.5 mg the 1st night. Slept well but a little groggy the next day. Didn't get much accomplished. 2nd night same dose and the next day was a total loss. Just sat in my chair all day. No energy or drive. Then I tried to further the dose by cutting 15 mg into 7.5 mg into 3.75 mg. That's next to impossible due to the shape of the half tab. One night you get decent dose and the next you get the smaller quarter and it doesn't work. Too bad hey don't come in 10 mg tabs.  For me, a big guy, with lots of body mass 3.5 mg would be a good dose but it's impossible to get with any accuracy."