You could also try Slippery Elm Bark powder, which is useful for normalizing the water balance in a cat's intestinal tract. Here's a link to check out:
http://www.littlebigcat.com/?action=...em=slipperyelm
Do you normally feed dry or wet food? Cat's are more prone to constipation when fed only dry as they tend to be chronically dehydrated.
Here's some more info on feline constipation (although I don't agree with everything in it, such as the use of petroleum jelly - but it does otherwise have some helpful tips):
http://www.pawpathlittermat.com/Arti...nstipated.html
for normal pooping from now on!