Do eardrops invalidate fasting?
There is a channel between the ear and throat. However, medication does not reach throat because eardrum plucks this channel. Therefore eardrops do not invalidate fasting.
Even if there is a hole on the eardrum, medication does not reach stomach or only a little amount reaches because it is absorbed inside the ear. Moreover, this process does not mean eating and drinking. Therefore, eardrop does not invalidate fasting (Decision by HBRA dated 22.09.2005; see. Marghinani, al-Hidayah, II, 263; Kasani, Bada’i, II, 98; Ibn Abidin, Radd al-Muhtar, III, 367,376).
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS