November 14, 2019
When traditional oral analgesics no longer control pain, some physicians are turning to alternative drug delivery methods that provide pain relief while avoiding systemic adverse effects (AEs).
Intrathecal (IT) drug delivery may offer patients more sustained relief for localized, neuropathic pain because it targets the kappa-opioid receptors without the mu-opioid receptor effects, which can produce respiratory depression, euphoria, and dependence.
For years, the US Food and Drug Administration had approved only 2 drugs for IT administration for pain relief: ziconotide and preservative-free morphine.Many of the drugs expert consensus recommends are used off-label in IT therapy:
Patient Selection Is Critical
Although physicians acknowledge that IT therapy is not for every patient with chronic pain, select therapies may have enduring relief.1 To that end, the Polyanalgesic Consensus Conference (PACC) convened in 2016 to recommend best practices for IT therapy.
Some of the patient and therapy considerations include:
- Type and location of pain
- Prior opioid exposure
- Patient comorbidities
- Catheter location
- IT space pharmacokinetics
- Physiochemical properties of medication
- Device variables
- Cerebral spinal fluid flow dynamics
The patients who experience the greatest success with IT therapy tend to have localized pain, although some IT experts say that patients with diffuse pain can be treated this way. For elderly patients, IT therapy may provide alternative analgesia to reduce polypharmacy and the adverse effects of oral and transdermal medications.
“[IT] opioid therapy is indicated only in a small portion of all patients with chronic pain,” explained Tilman Wolter, MD, PhD, from the Interdisciplinary Pain Center, University Hospital Freiburg in Germany. “In Germany, estimates range in the order of 12 million patients with chronic pain, and there are about 2000 pump implantations per year, just to illustrate the order of magnitude. Nonetheless, in carefully chosen patients, younger and elderly patients, [IT] opioid therapy can be an option.”
Switching From Systemic to IT Therapy
One of the most challenging aspects of pain management is maintaining analgesia from oral systemic medications to adequate levels delivered intrathecally. In a 4-year retrospective study of 220 patients with cancer (mean age, 62±12 years; 43% women) with refractory pain, only 32% achieved early pain relief, defined as 0 to 7 days after implantation of an IT device. One factor that contributed to early pain relief was using an appropriate initial ratio of local anesthetic to morphine, although the researchers caution there is no one correct formula.
Not surprisingly, patients whose performance status was better fared better in converting from oral medications to IT delivery.
“Patients try more than 2 or 3 different medications before IT treatment. We fight to implant patients sooner with lower doses and after only an opioid trial, especially for some cancers where IT is very effective, like pancreatic cancer or Pancoast-Tobias syndrome,” told Denis Dupoiron, MD, anesthesiologist from the Western Cancer Institute in Angers, France, in an interview with Clinical Pain Advisor.
TAGS: Neuropathic, Pain, Intrathecal Drug Delivery, Clinical Pain Advisor, Systemic, IT Therapy