Fast Fact and Concept #53: Sublingual Morphine

Author: Debra Gordon, RN

2nd Edition  

The preferred route of analgesia for most patients in pain is oral ( PO). Soluble tablets of morphine are available for sublingual (SL) administration in patients who are unable to swallow oral analgesics. The advantage of using SL morphine over intermittent RN IV boluses is a longer duration of action. An IV bolus may last only 1-2 hours, whereas SL morphine may provide relief for up to 4 hours.

Sublingual (SL) administration of morphine is often used to treat breakthrough pain in an attempt to hasten analgesic onset and peak, however, available data do not support more rapid absorption of morphine through the sublingual mucosa when compared with the oral route 1-3. Indeed, a number of clinical studies have found no substantial advantage to the use of SL morphine over oral morphine. 4-6

• Mean time to maximum concentration has been shown to be shorter following PO morphine (0.8 + 0.35hr) compared with SL (1.75 + 1.30 hr), indicating that SL morphine is likely swallowed and absorbed gastrointestinally rather than through the oral mucosa 3.
• The bioavailability (amount of drug eventually made available to the systemic circulation) of SL morphine is only 9% compared with 23.8% after an oral solution (however, the PO and SL doses should be considered equianalgesic when calculating doses).
• Agents are most readily absorbed through the oral mucosa when they are potent, non-ionized at physiological pH, and lipid soluble (see Fast Fact #103). Morphine has a relatively low potency for an opioid, is 90% ionized at the pH of the mouth, and is one of the least lipid soluble opioids with a partition coefficient of 0.00001, providing an explanation for its low bioavailability and poor choice as a SL or buccal medication.

There are several forms of short acting PO morphine available on the market. However, only the soluble tablets or the concentrated oral solution are suitable for SL use. Nonsoluble morphine sulfate immediate release (MSIR) tablets will not work because they are not soluble and will not liquefy under the tongue.

A usual starting dose for an opioid naïve patient is 5-30mg PO or SL every 3-4 hours. PO and SL doses are considered equianalgesic. The equianalgesic ratio of IV to PO morphine is 1:3 (10mg of IV morphine is approximately equianalgesic to 30mg PO/SL morphine).

This Fast Facts was adapted with permission from: http://www.hosp.wisc.edu/CRIT/guides/pain/paincentral.htm

University of Wisconsin Hospital & Clinics, Madison, WI Pain Patient Care Team

1. Osborne R, Joel S, Trew D, Slevin M. Morphine and metabolite behavior after different routes of morphine administration: demonstration of the importance of the active metabolite morphine-6-glucourinide. Clinical Pharmacology Therapy 1990;47:12-19.
2. David T, Miser AW, Loprinzi CL, Kaur JS, Burnham NL, Dose AM, Ames MM. Comparative morphine pharmacokinetics following sublingual, intramuscular, and oral administration in patients with cancer. The Hospice Journal 1993;9(1):85-90.
3. Colluzzi PH. Sublingual morphine: efficacy reviewed. Journal of Pain and Symptom Management 1998;16(3):184-192.
4. Pannuti F, Rossi AP, Iafelice G, Mararo D, Camera P, Cricca A, Strocchi E, Burroni P, Lapucoi L, Fruet F. Control of chronic pain in very advanced cancer patients with morphine hydrochloride administered by oral, rectal, and sublingual routes: clinical report and preliminary results on morphine pharmacokinetics. Pharmacological Research Communications 1982;14(4):369-380.
5. McQuay, H.J., Moore, R.A., Bullingham, R.E. Sublinqual morphine, heroin, methadone, and buprenorphine: kinetics and effects. In K.M. Foley & C.E. Inturrisi (Eds.). Advances in Pain Research and Therapy, Vol 8. New York: Raven, 1986; pp 407-412.
6. Robinson JM, Wilkie DJ, Campbell Sublingual and oral morphine administration. Review and new findings. Nursing Clinics of North America 1995;30(4):725-743.

Fast Facts were edited by David Weissman MD, Palliative Care Center, Medical College of Wisconsin until January 2007.  For comments/questions write to the current editor, Drew Rosielle MD: drosiell@mcw.edu. The complete set of Fast Facts is available at EPERC: www.eperc.mcw.edu

Copyright/Referencing Information: Users are free to download and distribute Fast Facts for educational purposes only. Citation for referencing: Gordon D. Fast Facts and Concepts #53, Sublingual Morphine, 2nd Edition. July 2006. End-of-Life/Palliative Education Resource Center www.eperc.mcw.edu.

Purpose: Instructional Aid, Self-Study Guide

Audience(s)

ACGME Competencies: Medical Knowledge, Patient Care

Keyword(s): Pain>opioids