PRN pro re nata PRN PRN pro re nata p.r.n. or Pro re nata pro re nata PRN pro re nata pro re nata pro re nata PRN (as needed) pro re nata PRN PRN PRN pro re nata PRN P.R.N. means PRN pro re nata pro re nata (administer as needed or as the situation arises) P.R.N. means PRNs PRN PRN pro re nata PRN PRN pro re nata pro re nata PRN medication prn PRNs ad hoc PRN PRN PRN pro re nata (administer as needed or as the situation arises) PRN PRN PRN Pro re nata pro re nata PRN PRN PRN