K.M.
Hi,
I checked Dr. Hale's website for you:
http://neonatal.ttuhsc.edu/lact/medicationforumspage.html
Enter as a guest and look under the analgesics category and there's a post on neurontin. Dr. Hale specifically does studies on breastfeeding and medications so he's an expert in this area. Here's what he said:
Nothing has yet been published on Neurontin(gabapentin), however I know a number of moms who've used much higher doses and breastfed successfully.
We've done milk levels on a few mothers and levels are not excessively high, but I cannot tell you its absolutely safe.
It's dated from 2003 though, so his most recent copy of Medications and Mother's Milk might have it in there now. You could try calling someone from your local La Leche League and see if they can look it up for you.