Dr. Walt Stoll says that Nystatin tablets reach the colon. Nystatin was his go-to medicine for patients. Here’s his board archives from the late 1990s.
my computer is having issues so i can’t find the specific posts, but he says it works to reach the colon. he recommends also swishing nystatin around in the mouth and swallowing. if you’re using tablets, you can crush them to accomplish this.