Using suppositories during the day does not invalidate the fast. Similarly if a fasting person needs an enema, that does not invalidate the fast, because there is no evidence to suggest that this is one of the things that break the fast, and because that is not food or drink and does not come under the same heading as food and drink.
Shaykh al-Islam Ibn Tayimiyah said in al-Ikhtiyaaraat p. 193:
Application of kohl and enemas do not invalidate the fast… this is the view of some of the scholars.
Shaykh Ibn ‘Uthaymeen said in al-Sharh al-Mumti’ (6/381):
The most correct view concerning this matter is the view of Shaykh al-Islam Ibn Taymiyah – i.e. that an enema does not invalidate the fast.
And Allaah knows best.