OK, I am not very familiar with toltrazuril. It is made by the same company as ponazuril, which to me says that it has a somewhat different activity--there are two reasons a company would create a drug that is highly structurally similar to one on the market (1) they are trying to get around the patent protection another company has on the already marketed drug and (2) it works better. The body converts toltrazuril into ponazuril, but my concern is that this metabolism takes place in the liver, and then most of the drug is removed from the blood because of how oral medications are dealt with in the body. I would just guess that the reason ponazuril is better is that it is better at getting in the brain because it gets there before it is exposed to the body's detoxification organs (liver and kidneys), and giving a higher dose of toltrazuril could circumvent that problem.
I am glad, though, that you have at least considered it. It's strange that there's such a price difference when they're both under patent and both from the same company.
