At the risk of being a total pain in the ***, you need to bear in mind that the distribution of the active ingredient in pills and tablets is notoriously random. Its one of the well known problems with people splitting pills and tablets. Because the active ingredient is not necessarily evenly spread throughout the whole tablet, each half can contain dramatically different amounts of the active ingredient. Given that your instructions and the doses are supposed to be precise, you need to bear in mind that however careful you are (and assuming you even have the drug you think you do) splitting a tablet means you can't ever be certain about the dose you actually get.

I'm not trying to be difficult - I just think you need to fully factor in the significant risks and issues there are with both your materials and methodology.