You can buy something called Fibregel, but it's pretty heavy duty, for people with IBS etc. I remember my dad taking it and saying it made him go to the toilet a lot.
What do you use them for?
Is that the liquid stuff? I think thats a bit too hard core.
I use psyllium husks if I need more fibre, from GNC, H&B etc. It's just this powdery stuff that you mix into water and drink, it does go jellyish if you leave it more than a couple fo minutes though.