Other than the other drugs that have the essentially the same mechanism which I previously mentioned, I'm not sure what to suggest as far as meds - sorry about that. But I hope the company will get back to you with some suggestions.
The only other thought I have is one that some people might consider a bit 'far out,' but it does work for some (intrepid individuals). It's a form of visceral manipulation that can help in those with pre and post GB problems depending upon what's actually going on. And it's like everything else, works for some but may not help others for whatever reason.
I've found from being around people with this condition that when the area of the sphincter of Oddi is gently pressed, it seems to ramp up the nausea 'signal.' In those who are worked on in a face-up lying position, gently pressing will cause them to say that they can 'feel that right up to my throat and I feel like I want to throw up.' Some trained manual therapists can gently stretch that area and it seems to down regulate the feeling and decrease the spasming of the duct.
I've mentioned it in a couple of posts, one with a gentleman who may or may not have GB problems, but to use it to possibly stop the problem before it starts. See:
http://www.medhelp.org/posts/show/542609 if you're interested. But it can also be used after surgery.