Opioid-Naive and Opioid-Tolerant Patients
Opioids are the mainstay of cancer pain treatment, and many of the guideline changes deal with how these agents should be selected and used in cancer patients.
New to the adult cancer pain guidelines are the terms "opioid-naive" and "opioid-tolerant" patients. Previously, the pain management algorithms divided patients into those "not currently taking opioids," and "currently taking opioids." The panel of experts asserts that these categories did not adequately reflect how patients were likely to respond to opioid therapy, particularly when escalation of dose is being considered.
The terms opioid naive and opioid tolerant are now clinically accepted and widely used, especially in the pain arena. The NCCN uses the US Food and Drug Administration (FDA) definitions for these characteristics.
Opioid tolerant: patients who are taking, for 1 week or longer, at least:
60 mg oral morphine/day;
25 µg transdermal fentanyl/hour;
30 mg oral oxycodone/day;
8 mg oral hydromorphone/day;
25 mg oral oxymorphone/day; or
An equianalgesic dose of any other opioid.
Opioid naive: patients who do not meet the above definition of opioid tolerant, and who have not taken opioid doses at least as much as those listed above for 1 week or longer. The NCCN v.2010 pain management algorithms also supply simpler definitions for these terms:
Opioid naive: patients who are not chronically receiving opioid analgesics on a daily basis; and
Opioid tolerant: patients who are chronically receiving opioid analgesics on a daily basis.
Analgesic tolerance renders the patient less susceptible to the effects of opioids, including both pain relief and most adverse effects. The practical significance of a patient's experience with opioids is that the opioid-tolerant patient is much less likely to respond to the administration of opioids with deep sedation or respiratory compromise. However, no tolerance develops to the side effect of constipation. The designations -- opioid-naive and opioid tolerant -- are used throughout all of the algorithms in NCCN v.2010. Paice explains the rationale for adding these classifications to NCCN v.2010: "We are trying to help clinicians who are faced with a patient who is having a pain crisis or is in very severe pain, to give the clinician more guidance, comfort, and permission, if you will, to be more aggressive in increasing the opiate dosage in opioid-tolerant patients. If the patient is opioid naive, the clinicians must go a little slower with dose escalation and do more monitoring of the patient's response." The opioid-naive patient is at greater risk for complications, and particularly, sedation and respiratory depression.
Paice acknowledges that it isn't always easy for clinicians to ascertain if a patient is opioid tolerant, and no standard, across-the-board definition of opioid tolerance has been accepted by all professional pain societies. Many clinicians wonder, if a patient takes 1 dose a day of an opioid, are they considered to be naive or tolerant? The answer, says Paice, "probably depends on the patient." Paice finds that healthcare professionals are now fairly savvy about the differences among tolerance, dependence, and addiction, but acknowledges that concerns about excessive sedation, and respiratory depression might contribute to underdosing of pain medication, even in patients at low risk for these effects.
Patient Fears About Tolerance
According to Paice, "evidence suggests that patients fear tolerance to opioid medications. The word I hear in the clinic is 'immune,' they fear that they will become immune to the pain medication, that it will stop working, if they take it too early in the course of disease. They will save the medication for 'when they really need it,' not understanding that the dose can be increased."
Fear of "The Last Dose"
Paice describes a phenomenon seen not only with families but also with nurses, in acute care as well as hospice settings that occurs when giving pain medication at the end-of-life. The nurse or family member is reluctant to administer pain medication to the patient who is clearly dying because they think the medication will accelerate the dying process. They call this "the last dose," because of fear that it will be the last dose, and that the medication rather than the cancer is somehow killing the patient. However, notes Paice, "We have good studies looking at doses of morphine and time of death in cancer patients, and there is no correlation. When I share that with nurses and family members, it does give them comfort. It is a huge fear towards the end of life."
Medscape Oncology © 2010
Cite this: Laura A. Stokowski. Adult Cancer Pain: Part 2 -- The Latest Guidelines for Pain Management - Medscape - Dec 06, 2010.