Anything that is regarded as coming under the same heading as eating and drinking invalidates the fast because it provides the body with energy. The evidence is in the same verse that invalidates eating and drinking. This includes:
Transfusion of blood to one who is fasting – such as if he bleeds heavily and is given a blood transfusion. This invalidates the fast because blood is formed from food and drink.
Receiving via a needle (as in the case of a drip) nourishing substances which take the place of food and drink, because this is the same as food and drink.