I've just found this website, peanut butter flavouring (and lots of others)! If you're thinking of getting some of the lorann oil, don't worry they don't actually contain any oil Flavours
I've not tried them. But don't be fooled, the price seems reasonable but with the lorann oils you only get 1 dram which is apparently equivalent to about 1 teaspoon. They claim you only need a few drops to flavour an entire recipe but still! As for the ingredients, none contain oil and most of them don't contain alcohol (some flavours do though), they contain propylene glycol. They don't seem to contain anything different to the flavourings sold by the Dukan website so I see no reason we couldn't have these in our muffins
Anyway, I will be receiving some pb flavouring from the states so I'll let you all know how it tastes!