I do not think gabapentin is "very"safe. It is safer than than the other antiseizure drugs out there, which have some serious long term toxicities. Gabapentin is not metabolized so it is not going to affect other treatments liver-wise also.

But it is a DRUG and carries significant side effects of its own. Mostly weight gain, mental confusion and other lifestyle losses.
Quality of life on it is not great considering is low effectiveness potential.

The same comments are given by doctors and the propaganda net about SSRI drugs being SAFER than TCAs . I got that in all my CEs and seminars for many years. The only "safer" aspect is that SSRIs have a lower death rate for overdoses or suicide attempts (from depressive patients). The TCAs had significant long QT effects and affected the heart in high doses or mixed with other drugs.

So the term "safer" is very relative IMO.