This could have something to do with Jazz Pharmaceuticals (makers of Xyrem) have been bought be a Belgian or Ireland company.
SDS Pharmacy will confirm this as they have had plenty of calls about Xyrem about this particular condition or situation. I have taken Xyrem on 3 different occasions. The first 2 times went real well and reason for starting and stopping was changing of insurance and amount of co-pays. The 3rd time I took it was approximately 6 months ago and after about 3 weeks I developed anxiety and panic so severe that I did not think I was going to make it. After about 3 days I had to take .5mg of Xanax and within 30 minutes I felt as if I had never took it to start with, but of course that did not last long. I called SDS Pharmacy and they have several accounts of people that are going through a period if severe anxiety (which I was this time and was not the first two times I took it). SDS on the other hand did not have any answer and could not get one out of Jazz Pharmaceuticals. Their answer was to stop taking the med, which I did and in about 6 -7 days the anxiety subsided and I waited about a week and started up slow again. After 3-4 days the anxiety was back and just as bad.
What I can't figure out is something that has a half life of about 3 hours can cause severe panic and anxiety for 6-7 days. I know a lady that takes it for 3 days on and 3 days off, while taking Ambien on the days off and she does fine, but she cannot take Xyrem any longer than than that without severe anxiety and panic and occasional emergency room.
Xyrem effects something that severe stress effects as well and last longer than 30 times it's half life. The only thing that I noticed different is that in the mornings when I woke up, I actually jumped straight up in bed before I could even open my eyes good. I'm would think it has an effect on more than just GABA. Some people feel like it cause a dopmine surge, but I have not found any scientific study to confirm this and SDS Pharmacy and Jazz Pharmaceuticals does not seem to want to give an answer if they have one.
Just a word of caution!