Download 1.19 Mb.
Treating patients in medication- Assisted recovery
Goals for treating CNCP in patients who are in medication-assisted recovery are the same as for patients who are in recovery without medications: reduce pain and craving and improve function. As with other patients:
• Start with recommending or prescribing nonpharmacological and non-opioid therapies.
• Treat comorbidities.
• Closely monitor treatment outcomes for evidence of benefit and harm.
Patients receiving opioid agonist treatment for addiction require special consideration
when being treated for chronic pain. In these
patients, the schedule and doses of opioid ago nists sufficient to block withdrawal and crav ing are unlikely to provide adequate analgesia. Because of tolerance, a higher-than-usual dose of opioids may be needed (in addition to the maintenance dose) to provide pain relief.
Patients who have CNCP and are using sublingual buprenorphine treatment of opioid addiction pose special challenges. The drug
is a partial mu agonist that binds tightly to the receptor. Because it is a partial agonist, its dose–response curve plateaus or even declines as the dose is increased. Thus, a ceiling dose limits both the available analgesia and the toxicity produced by overdose. Nevertheless, buprenorphine is an effective analgesic, and some patients who have addiction and CNCP may receive benefit for both conditions from it. To optimize analgesic efficacy, the drug should be given three times a day when pain reduction is a goal. High doses of buprenor phine can attenuate the effects of pure mu agonists given in addition to it. High doses tend to reduce the reinforcing effects of inap propriately consumed opioids but, at the same time, may reduce the effectiveness of opioids given for additional analgesia in the case of trauma or acute illness (Alford, Compton, & Samet, 2006).
Because buprenorphine has such high affinity for the mu receptor, it displaces full agonists and can induce acute opioid withdrawal; for example, if a patient on chronic methadone is given a dose of buprenorphine, acute opioid withdrawal may be precipitated (see CSAT  for more information).
The use of buprenorphine for pain is off- label, albeit legal. Whereas clinicians must obtain a waiver to prescribe buprenorphine for an SUD, only a Drug Enforcement
Administration (DEA) registration is required to prescribe buprenorphine for pain. To clarify (for pharmacists) that a prescription does not require the special DEA number, it is useful
to specify on the prescription that the drug is “for pain.”
Patients who have chronic pain do not obtain adequate pain control through a single daily dose of methadone because the analgesic effects of methadone are short acting in comparison with its half-life. The dosing schedule for
the treatment of opioid addiction does not effectively treat pain, although the single dose often provides transient analgesia.
Methadone effects vary significantly from patient to patient, and finding a safe dose is difficult. Methadone’s analgesic effects last approximately 6 hours. However, its half- life is variable and may be up to 36 hours in
some patients. Pain patients may take 10 days or longer to stabilize on methadone, so the clinician must titrate very slowly and balance the risk of insufficient dosing with the life- threatening dangers of overdosing (Heit & Gourlay, 2008) (Exhibit 3-5). It is critical for the clinician to advise patients to stop metha done treatment if they become sedated.
Methadone is an especially desirable analgesic for chronic use because of its low cost and
its relatively slow development of analgesic tolerance; however, it is also especially toxic because of issues of accumulation, drug inter action, and QT prolongation. For these reasons, it should be prescribed only by providers who are thoroughly familiar with it.
It is critical that patients starting methadone receive a thorough education in the dangers
of inadvertent overdose with this medication. They must understand that a dose that seems initially inadequate can be toxic a few days later because of accumulation. They should be
advised to keep the medication out of reach
so that they cannot take a dose when sedated. Furthermore, they must be informed of the extreme danger if a child or nontolerant adult ingests their medication. Chapter 5 provides more patient education information, and CSAT (2009b) describes emerging issues
in the use of methadone.
Patients taking naltrexone should not be prescribed outpatient opioids for any reason. Naltrexone is a long-acting oral or injectable mu antagonist that blocks the effects of opioids. It also reduces alcohol consumption by imped ing its rewarding effects. Because naltrexone displaces opioid agonists from their binding sites, opioid analgesics will not be effective
in patients on naltrexone. Increasing the dose of opioids to overcome the blockade puts
the patient at risk of respiratory arrest. Pain relief for these patients requires non-opioid modalities.
If patients on naltrexone require emergency opioids for acute pain, higher doses are required, which, if continued, can become toxic as nal trexone levels wane. In this situation, inpatient or prolonged emergency department monitoring is required (Covington, 2008).
Tolerance and hyperalgesia
Tolerance develops rapidly to the sedating, euphoric, and anxiolytic effects of opioids. It develops more slowly to their analgesic
effects and seldom develops to their constipat
ing effects. Tolerance can be characterized as decreased sensitivity to opioids, whereas OIH is increased sensitivity to pain resulting from opioid use. In a clinical setting, it may be impossible to distinguish between the two conditions, and they may coexist (Angst &
Clark, 2006). Tolerance can develop in chronic opioid therapy regardless of opioid type, dose, route of administration, and administration
3—Chronic Pain Management
schedules (DuPen, Shen, & Ersek, 2007).
Hyperalgesia has been found to result from the use of those opioids thus far studied (i.e., methadone, buprenorphine, sufentanyl, fentan yl, morphine, heroin). Patients in MMT expe rience analgesic tolerance and OIH. Clinical implications of these findings are unclear, as studies indicate that OIH may develop to
some measures of pain (e.g., cold pressor test)
and not to others (e.g., pressure) (Mao, 2002).
When patients develop tolerance to the analgesic effects of a particular opioid, either dose escalation or opioid rotation may be useful (Exhibit 3-6). Opioid rotation, switch ing from one opioid to another, is a way to exploit incomplete cross-tolerance to achieve improved analgesia without an increase in (equivalent) doses.
If a patient requests an increase in opioid dose, it is important for the clinician to try to discern whether the patient is experiencing increased pain or analgesic tolerance or is seeking some other effect (e.g., sedation, reduced anxiety).
In the patient seeking sedation or reduced anxiety, a larger opioid dose provides temporary anxiolytic or sedative effects, but tolerance soon develops, necessitating another dose increase. To avoid a cycle of dose increases, the clinician should evaluate the patient’s request. When nonanalgesic effects seem to be the basis for
the request, alternative non-opioid medications should be provided and opioid doses should not be increased.
As with tolerance, OIH appears to require
increased doses of opioids to achieve previ ous levels of analgesia. However, with OIH, increased doses could exacerbate pain. Treating pain with a multimodal approach—in addition to analgesics—may reduce the need for opioids, thereby decreasing the risk of tolerance and OIH.
Treating pain in patients Who have Active Addiction
The presence of active addiction—whether to alcohol, opioids, or other substances—makes successful treatment of chronic pain improb able (Covington, 2008; Weaver & Schnoll,
2007). For patients who have active addiction and CNCP, it may be impossible for clini cians in the primary care setting to provide the comprehensive services necessary to treat both conditions. Specifically, an active SUD indicates that the patient should be referred for formal addiction treatment. The clinician should work closely with the patient’s SUD treatment provider.
If the patient refuses the SUD referral, the clinician can use motivational interviewing techniques. CSAT (1999b) provides more information on motivational interviewing. If the patient still does not consent to addiction treatment, he or she should not be prescribed scheduled medications, except for acute pain
or detoxification. CSAT (2006) provides more information on detoxification.
exhibit 3-6 opioid rotation
When an opioid is ineffective, becomes ineffective, or produces intolerable side effects, it is com mon practice to rotate opioids. This practice is based on the observation that particular opioids affect people differently, primarily because of intraindividual and interindividual variability among opiate receptors, so-called mu-receptor polymorphism. Although most opioid analgesics are mu agonists, they affect some mu receptors differently from others. A Cochrane review (Quigley, 2004) looked at the evidence supporting the replacement of an opioid to which an individual has devel oped analgesic tolerance with a different opioid. The conclusion was that although evidence is scant, the practice appears to be efficacious. The most common opioid rotation, and most studied, is from morphine to methadone.
Once the patient’s SUD recovery is stable, the likelihood of managing his or her pain increases. The need for formal addiction treatment often necessitates a change in the plan for opioids,
by discontinuing them or by changing the treatment setting through which they are provided.
Acute pain episodes
When patients who have CNCP and an SUD require acute pain management, such as for postoperative pain, precautionary steps can minimize risk of relapse.
Patients in recovery may benefit from non- pharmacological pain control. Some patients in recovery from SUDs may prefer to avoid the use of any medication. Evidence shows that stress management, CBT, manual thera pies, and acupuncture offer effective relief for certain types of acute pain (Hurwitz et al.,
2008; Vernon, Humphreys, & Hagino, 2007).
Patients in recovery may benefit from being switched from short- to long-acting medica tions as quickly as appropriate (to minimize reinforcing effects). They may also benefit from bolstered recovery support during post operative periods (Covington, 2008).
Patients on agonist therapy for addiction or pain may be continued on their current opioid or on an equivalent dose of an alternative opi oid; however, this should not be expected to control acute pain, which requires supplemen tation with (often greater-than-usual doses of ) additional opioids. In this situation, adjuvant NSAIDs may allow clinicians to provide
pain relief with a reduction in opioid dosage (Mehta & Langford, 2006), and multimodal analgesia should be considered (Maheshwari, Boutary, Yun, Sirianni, & Dorr, 2006).
Patients on buprenorphine for opioid addiction may have reduced benefit from full agonist opioids used for acute pain, because
the full agonist will be somewhat blocked. Non-opioid analgesics can be used, but in some cases buprenorphine will need to be dis continued so that full agonist opioids for pain can be used (Alford et al., 2006).
Patient-controlled analgesia should have relatively high bolus doses and short lockout intervals (specified intervals during which pressing the administration button results
in no drug delivery), and patients should be closely monitored by medical staff. Pulse oximetry or end-tidal CO2 monitoring may
provide an additional margin of safety when
high doses of opioids are required.
Patients who are dependent on opioids or sedatives (including benzodiazepines) should not be withdrawn from these medications while undergoing acute medical interventions.
Exhibit 3-7 provides a discussion of treating patients who have sickle cell disease (SCD), which brings recurring acute pain, often against a backdrop of persistent pain and hyperalgesia.
Other comorbidities that can complicate pain treatment result from other chronic illnesses. Exhibit 3-8 offers suggestions for providers
for treating CNCP in patients who have HIV/ AIDS.
Assessing Treatment outcomes
Treatment of chronic pain is usually an evolving process, with medication and adjunctive thera pies attempted, monitored, and adjusted or abandoned as indicated by patient response. Chapter 2 provides information about ongoing assessments.
3—Chronic Pain Management
exhibit 3-7 Treating patients Who have sickle cell Disease
SCD is characterized by crises of acute pain, attributed to vasoocclusion, that is typically nocicep tive but can be neuropathic as well. Opioids are the mainstay of treatment, although parenteral ketorolac may suffice in some crises and have opioid-sparing effects in others.
Acute pain management is critical but is often poorly conducted. At times, mutual mistrust between the patient and the clinician may lead to fears of being discounted on the part of the patient and suspicions of symptom exaggeration on the part of the clinician.
The development of CNCP further complicates the situation. When there is a clear structural explanation for pain (e.g., leg ulcers, avascular necrosis, osteomyelitis), appropriate (typically opi oid) therapy is usually provided. Many patients, however, report chronic pain in the absence of detectable peripheral pathology. This pain has been attributed to central sensitization as a result
of multiple episodes of severe pain. It can also result from ischemic neuropathic conditions. A small percentage of patients who have SCD develop an SUD, which adversely impact their pain reports and treatment responses.
It is generally accepted that appropriate treatment of an SCD crisis requires prompt and aggressive analgesia. Some hospitals and emergency departments keep a log of SCD patients that documents their degree of opioid tolerance, typically effective agents, and doses required so that near-imme diate relief can be provided to patients presenting for care. Chronic pain with persistent tissue pathology likely requires continuation of substantial opioid doses for acceptable relief, although peripheral and adjuvant agents should be used as appropriate.
The treatment of chronic idiopathic pain in SCD often requires a multidisciplinary approach with emphasis on adjuvant analgesics and nonpharmacological therapies, including psychological thera pies (Ballas, 2007).