Well there would still be the same consistency throughout the whole pill.  Otherwise it would be silly having a score mark on it and they would most definately have to make 2.50mg pills at the least.  So the manufacturers must be able to demonstrate that there is as 2.50mg in one half and 2.50mg in the other half.  So I would not worry about the other binding ingredients in the pill. 

I was out today and they have the pill cutters here now in the $2 shop.  (Everything in the shop is $2 NZ).  Mine was given to me by a friend and I have had it for about 6 years so they are worth tracking down.  In fact if you do a search for them on Google, you will find them at many online drug suppliers I’d imagine.  It must be difficult trying to cut to that size with a razor and I don’t think I could cut to that size using my pill cutter either.  the tablets that I have are very small with no score marks and I cut them into four pieces (1.25mg) easily with the pill cutter though. 

Given the difficulty of cutting to that dose, in fact I think that your Doctor should have prescribed suspension until your baby’s doses are at a suitable dose to cut up where using tablets are concerned.  I think there should be a limit to what they make us but to basically, unless it is specifically a parent’s chhoice because they do not mind struggling with it.