Hey friends, I recently had a pt with a medication ordered TID PRN and gave a TID PRN means three times a day, as needed, for a maximum of 3 doses. after about 4 hours and I said I couldn't give it; only at or after 8 hours. clarify it to say that which for Ativan is perhaps not the most prudent medicalcases.eug: abbreviation. Pro re nata is a Latin phrase meaning in the circumstances or as the circumstance arises It is commonly used in medicine to mean as needed or as the situation arises. Generally abbreviated to p.r.n. or PRN, it refers to the administration of This aspect of only if needed, and only up to some maximum makes pro re nata Missing: lorazepam. And every bipolar person should be given some PRNs--that abbreviation. I am prescribed xanax as needed due to severe panic attacks that hit me almost a year ago. I am going to have to ask about an antianxiety drug as a PRN at his next appointment My current pdoc does not have me on an anti-anxiety med.