Neuraxial (epidural and intrathecal) opioids for intractable pain

Abstract

There is an increasing evidence base for the use of neuraxial analgesia for chronic non-malignant pain (CNMP), cancer-related intractable pain and spasticity. Several drugs are available for use including opioids, local anaesthetics and adjuvant drugs such as clonidine and ziconotide. This review will focus mainly on the use of neuraxial opioids for CNMP and cancerrelated pain; a brief description of the action of the other drugs will be provided but not discussed in full. Patient selectionNeuraxial analgesia is considered for use in patients who have resistant intractable pain that fails to respond to other treatment options or pain that responds to analgesia but for which the doses required result in unacceptable side-effects. In rare circumstances it may be used for rapid, effective analgesia when there is limited time available for titration of oral or subcutaneous analgesia (e.g. end-of-life palliative care).Exclusion criteria relate specifically to psychological and psychiatric illness, allergy and certain physiological conditions which may be relative or absolute contraindications. If a significant psychological disorder, personality disorder, addictive personality or frank psychiatric illness is detected during the assessment and history-taking process then the patient is not considered suitable. Other exclusion criteria include depression, senility, suspected pain behaviour, alcohol or opioid abuse and poor physical condition. True allergy to any of the proposed analgesic or adjuvant drugs will preclude their use. Absolute contraindications include coagulation defects, local sepsis at the proposed Neuraxial (epidural and intrathecal) opioids for intractable painPaul Farquhar-Smith and Suzanne Chapman Summary Points 1. Neuraxial opioids are considered for use in patients who have resistant intractable pain that fails to respond to other treatment options or pain that responds to analgesia but for which the doses required result in unacceptable side-effects. 2. Neuraxial opiods can be considered for both chronic non-malignant pain and chronic cancer-related pain. 3. Effectiveness in chronic non-malignant pain and cancer pain is exerted through the use of either single-agent drugs (opioids) or a combination of drugs: opioids, local anaesthetics and other drugs such as clonodine and ziconotide. 4. Complications of long-term continuous infusion therapy are related to the insertion process (haematoma), the mechanical device (both pump and catheter) and the long-term effects of the drugs. 5. Patients will require ongoing ambulatory monitoring and supportive care.

Caudal epidural co‐administration of methadone and morphine in horses: An evaluation of analgesic properties and effects on locomotor function, mentation and physical examination parameters

“…Consequently, it was expected that when combining methadone and morphine for epidural administration, methadone would cover the long latency period from morphine. However, methadone is less potent than morphine when administered epidurally because potencies of epidural opioids are inversely related to lipophilicity (Farquhar‐Smith and Chapman 2012; Bujedo 2013). It is therefore possible that the level of sensitivity offered by the two mechanical stimulation modalities is only sufficient to detect the more potent analgesic effects of epidural morphine, but not the analgesic effects of epidural methadone, which would explain the apparent slow onset of action.…”

The Options for Neuraxial Drug Administration

“…Regarding neuraxial techniques in patients with cancer, there can be specific anatomical considerations to take into account. Vertebral metastases, spinal stenosis, loss of epidural fat in cachexia, and epidural invasion by tumors may complicate administration of neuraxial applied drugs and drug distribution [ 65 ]. Non-malignant pain conditions that may benefit from neuraxial drug-delivery systems comprise (among others) failed back surgery syndrome, lumbar post-laminectomy syndrome, complex regional pain syndrome and causalgia (complex regional pain syndrome type 2), phantom limb pain, and plexopathy [ 66 ].…”

“…Concerning opioids, numerous agents that are not approved for neuraxial administration have been used off-label in daily clinical practice, amongst others buprenorphine (which exerts also a local anesthetic-like effect [ 218 ]), tramadol, pethidine, methadone, or diamorphine [ 65 ]. Their effectiveness has incidentally been described, the safety profiles of those drugs have, however, never been investigated in larger clinical trials.…”

A narrative review of caudal epidural anaesthesia and analgesia in horses. Part 1: Safety and efficacy of epidural drugs

“…Opioids and alpha-2 adrenergic agonists are both potent analgesics, and when given in combination, their analgesic efficacy can be further enhanced through synergistic mechanisms (Goodrich et al 2002;Goodrich and Nixon 2003;Fischer et al 2009). The analgesic onset, duration and potency of different opioids vary depending on their lipid solubility (McMurphy 2011;Bujedo et al 2012;Farquhar-Smith and Chapman 2012). Thus, a hydrophilic opioid (i.e.…”

“…The analgesic onset, duration and potency of different opioids vary depending on their lipid solubility (McMurphy 2011; Bujedo et al . 2012; Farquhar‐Smith and Chapman 2012). Thus, a hydrophilic opioid (i.e.…”