Alternatives to Panacure?

I have one 2yo and two 1yo cats rescued about a year ago from a cat colony. One had bad diarrhea when we adopted. The two others were fine. Right now the one has another bout of giardia (or recurrence). This time I can't get any of them to eat the food with their panacure! Last time we had to use a slurry and syringe to get it into the big guy. One of them is still pretty skittish. I can't imagine giving her a slurry! What should I do?