Looks like Ativan is a benzo, "best started slowly with ramped dosage and discontinued slowly by tapering dosage". They also have this warning: "CAUTION: Excessive use of BDZ medications can result in addiction or aggravation of an anxiety disorder. The main symptom of excessive BDZ dosage is drowsiness. BDZ medications should only be used to make anxiety or panic tolerable, not eliminate anxiety entirely."

So I don't know that it would be PRN as people might overdo it on their own?