Cathartic in a sentence?

"We need to put cathartic in this medicine."

"She didn't think of gardening as a chore, really, in fact it was quite cathartic; it was one of the few activitities that could take away the stresses of those long days at the office."

engaging in an activity, e.g. photography, in one's every day life is particularly cathartic for the mind.

"At the least cathartic." is not a sentence. A sentence must contain a subject (noun) and a verb. The given phrase contains neither.

When it has a subject, verb, punctuation, capitalization, a predicate, and a complete thought. A sentence is a sentence when it is handed down by a judge (or a magistrate).