I was admitted to the hospital and an IV drip was inserted into my arm. Does this invalidate my fast?

If you are required to receive treatment in the hospital and have to be put on a drip, this might indicate that you are facing serious health issues which make fasting more challenging.

Hence, it is best that you break your fast and replace the days that you are unable to fast due to your illness on other days after Ramadan.

However, being put on a drip does not invalidate the act of fasting as it does not go through any of the open orifices.