Touching with the hand or embracing follow the same ruling as kissing. It does not matter if the injection was intraveinous or underneath the skin. The Prophet, upon whom be peace, was cupped while he was fasting. However, if doing this weakens the fasting person, it is disliked. This is related by al-Bukhari and others.
Vivisection follows the same ruling as cupping.
At-Tirmidhi called it hassan sahih. There is a hadith that supports their opinion. Malik and Abu Hanifah hold that it breaks the fast because that water reaches the stomach. If he was aware that he was fasting, it breaks his fast, as if he would have drunk intentionally. It is similar to having a fly enter the mouth and proceed to the throat.