Sheila,
I was on gabapentin for almost 7 years
and slowly increased it to 4200mgs/day over that period of time.
When it seemed to start losing its effectiveness at that high dosage,
I changed to Lyrica - about 3 yrs ago.
I also increased it, to get to the right dosage,
within the first 3 mos.
That seems to be working for me, at this moment in time.