Whatever it is, I think the recommended dosage for gabapentin (and some other things) is/may be too high. The few times I took gabapentin for my PN, 100 mg. was enough to stop the burning for up to 24 hrs. Back when I tried it for chronic pain I couldn't complete the upward taper—it fried my brain without providing any therapeutic effect (and there's some question that the damage was permanent).

I realize I may be the outlier, but I learned from those experiences and others to err on the side of caution when titrating medications. These recommended therapeutic dosages are determined by studies (Phase II, IIRC) done by Big Pharma (whose purpose is to sell more drugs—not less).

My DW also does fine on lower doses of gabapentin—usually 100 mg. (for fibromyalgia and/or cervical stenosis) and rarely (couple/few time a year) up to 300 mg. with bad flares. Since being on an elimination diet, she's taken almost none, and has been able to reduce other medications to a trickle as well...

We're all different, and 1800 mg may be the magic number for many/most—I just think it makes more sense to start low and stop when efficacy is acheived rather than assuming everyone is the same and scarfing down fistfuls of nostrums....

Doc