People with seizures have to go very slowly.

But others just a fair taper would work.

I'd drop the 100mg in the afternoon first for a day or two and see what happens. Sometimes it may take a few days to see effects.
This drug is cleared thru the kidneys and not metabolized at all,
so depending on your kidney clearance ability, that would show you how to taper.

Once off the 100mg you could then drop 300mg at night for at least 7-10 days.(that means 600mg a night for that time) If no problem, drop 200mg the next week or 10 days. (you would be taking 300 + 100 during that week).

Then drop the 100 the next 10 days. If it works okay for you and your pain is not terrible, just go down by 100 every 7 days, and then try off completely.

You can go slower if you want...alot depends on how you react pain wise... too much pain, and go slower. YOu may find you still need some, but at a lower dose. Typically when titrated up they do increments of 100mg. If you want, you can go down that way too.