I don't know. My understanding was that it was a surprise research finding specifically in cats.I take pregabalin which is a similar med to GBP (gabapentin), both are good for nerve pain and both have shown to be good treatments for anxiety. I take it for my peripheral and central neuropathy, and my leg spasms.
It makes me extremely drowsy and ‘chill’ as you say so I take it at night only. Both are a decent med for pain management also (I am about to take mine as I am typing this), but it makes me very unsteady on my feet - another reason I don’t take it during the day - don’t want my eyes pecked out falling down in the barn
I am sure it works wonderfully for your moggyI am seeing these type of meds being used more and more often in animals. I wonder if chooks can take it??
It is a very dramatic effect - she goes from a hissing, spitting monster to 'whatever'! It takes a couple of hours to wear off at home and she is a little wobbly on her feet - not too bad - basically she sleeps it off. But it is amusing to see how chill she is. She even purrs when you pet her tummy (normally she might bite if you do that uninvited).
Anyway, it is a game changer. Taking her to the vet was so stressful for her and therefore for me. She looked like she would explode and take the vet techs down with her.