I've ordered stuff in the past from Ainsworths of London and if you ring them and speak to the animal man, you can get some good advice.

One thing the vet did tell me was that you hadnt to touch any tablets with your fingers as that did something to the effect of them, but you had to feed them either with tweezers or straight out of the lid of the bottle. Something to do with the oils in your skin affecting them I think confused: