# 070 PRN Range Analgesic Orders, 2nd ed


Author(s): Debra B Gordon RN, MS, FAAN

Introduction Use of PRN opioid range orders (e.g. ‘morphine 2-6 mg IV q2h PRN’) is a common practice designed to provide flexibility in dosing to meet an individual’s unique needs. However, range orders have been shown to be a source of medication errors. It is critical that physicians, nurses, and pharmacists share a common understanding of how to properly write, interpret, and carry out PRN range orders.

Considerations for writing and interpreting PRN range opioid orders:

  • Reasonable range  A range order should be large enough to provide options for dose titration, but small enough to ensure safety. The maximum allowable difference between the high and low dose for analgesic dose range orders should be no more than four times the lowest dose (eg. four times 2 mg is 8 mg).
  • Patient’s prior drug exposure  If the patient is opioid-naïve, the first dose administered should be the lowest dose in the range; if the patient is opioid tolerant, or has received a recent dose with inadequate pain relief and tolerable side effects, a dose on the higher end of the range is acceptable.
  • Prior response  Inquire about this patient’s response to previous doses. How much relief did prior doses provide, and how long did it last? Did the patient experience side effects?
  • Age  For very young or elderly patients, start low and go slow – begin with a low dose and titrate up slowly and carefully.
  • Liver and renal function If your patient has hepatic or renal insufficiency, anticipate a more pronounced peak effect and a longer duration of action.
  • Pain severity  As a general rule, for moderate to severe pain increase the dose by 50-100%; do not increase by >100% at one time. To “fine-tune” the dose once pain is at a mild level, increase or decrease by 25%.
  • Anticipated pain duration  Is the pain acute, chronic, or progressive (likely to worsen)? In other words, is the patient likely to require more or less analgesic over time?
  • Kinetics  Know the onset, peak, and duration of action for the specific drug ordered. Unlike scheduled long-acting opioid formulations, doses of short-acting opioids can be increased at each specified dosing interval,
  • Co-morbidities  Debilitated patients, or those with respiratory insufficiency, may be at more risk for hypoxia if oversedated.
  • Use of other sedating drugs  When other CNS depressants are administered in combination with opioids, the dose of each medication required to achieve the desired effect may be 30-50% less than if either drug was administered alone.
  • Combination drugs  Limit doses of combination drugs: opioids with acetaminophen or an NSAID. Average adults should not receive more than 4000 mg of acetaminophen in 24 hours. Combinations drugs may contain as much as 750mg of acetaminophen per tablet. If substantial upward dose titration is required or anticipated, use opioid-only preparations.

Example Opioid naïve patient arrives with the order ‘Morphine sulfate 2-6 mg IV every 2h PRN pain.’ Give 2 mg for first dose. Reassess within 30 minutes. If adequate relief, reassess within next 2 hours. If no side effects but inadequate relief – may give 4 mg more in 30 minutes or when time to peak effect has passed from first dose. Total dose therefore is 6 mg in a 2-hour period.

Document patient response to PRN dosing

  • Reassess pain relief, side effects and adverse events produced by treatment, and the impact of pain and treatment effects on patient function, once sufficient time has elapsed to reach peak effect: 15-30 minutes after parenteral drug therapy or 1 hour after oral administration of a PRN analgesic or non-pharmacologic intervention.
  • Reassessments may be done less frequently for patients with chronic stable pain or for patients who have exhibited good pain control without side effects after 24 hours of stable therapy.

This Fast Fact was adapted with permission from the University of Wisconsin Hospital & Clinics, Madison, WI Pain Patient Care Team ‘Pain Management Fast Facts – 5 Minute Inservice’ series.

Gordon DB, Dahl J, Phillips P et al. The use of “as-needed” range orders for opioid analgesics in the management of acute pain: a consensus statement of the American Society for Pain Management Nursing and the American Pain Society. Pain Management Nursing. 2004; 5:53-58.

Fast Facts and Concepts are edited by Drew A Rosielle MD, Palliative Care Center, Medical College of Wisconsin. For more information write to: drosiell@mcw.edu. More information, as well as the complete set of Fast Facts, are available at EPERC: www.eperc.mcw.edu.

Version History: This Fast Fact was originally edited by David E Weissman MD. 2nd Edition published July 2006. Current version re-copy-edited April 2009.

Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Gordon D. PRN Range Analgesic Orders, 2nd Edition. Fast Facts and Concepts. July 2006; 70. Available at: http://www.eperc.mcw.edu/EPERC/FastFactsIndex/ff_070.htm.

Disclaimer: Fast Facts and Concepts provide educational information. This information is not medical advice. Health care providers should exercise their own independent clinical judgment. Some Fast Facts cite the use of a product in a dosage, for an indication, or in a manner other than that recommended in the product labeling. Accordingly, the official prescribing information should be consulted before any such product is used.

 ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Pain – Opioids