And we have a starting point for the initial dosag

And we have a starting point for the initial dosages, because of the doses used for the UP trial. The dose that was delivered by enema was applied directly to the target area -- it may be that a bit larger dose might be needed when delivered via time-release pill, as it might be spread out over a larger area so a bigger dose might be needed to get the right concentration in the target area.

But, it's smart to start with what you know and go from there. Also it's always better to start smaller and then increase, since you want to use the least amount of a drug possible to avoid side effects.