Chapter 10: Pain Management in Opioid Use Disorder (OUD)

The tenth chapter details the complex considerations necessary for managing pain in patients diagnosed with Opioid Use Disorder (OUD), a public health emergency often precipitated by undertreated pain, which is the most common reason for opioid misuse. Effective care requires addressing the underlying neurological changes, as chronic opioid use alters pain processing (nociception) and the mesolimbic reward pathway, leading to heightened pain sensitivity and tolerance. Providers must prioritize nonjudgmental screening and assessment for OUD, employing tools such as the Opioid Risk Tool (ORT) and the Screener and Opioid Assessment for Patients with Pain-Revised (SOAPP-R), supported by objective data from Prescription Drug Monitoring Programs (PDMP) and urine drug screens (UDS), noting the high risk of false results with initial immunoassay testing. The therapeutic strategy involves a multimodal approach aimed at eliminating pain, minimizing side effects, preventing relapse, and improving overall quality of life. Non-opioid analgesics and coanalgesics, including anticonvulsants and nonpharmacologic methods like Cognitive Behavioral Therapy (CBT), serve as first-line treatments. When Medication-Assisted Treatment (MAT) is required, first-line agents are buprenorphine and methadone, both of which act on the mu opioid receptor. Buprenorphine is a partial agonist that provides a ceiling effect on respiratory depression and euphoria, but its relatively short analgesic half-life (6–8 hours) means that for pain control, the typically once-daily OUD maintenance dose must be divided and administered two to three times daily. Methadone, a full mu agonist and Schedule 2 substance, carries a greater risk of respiratory depression due to the absence of a ceiling effect, and requires mandatory electrocardiography (EKG) monitoring due to the risk of QTc interval prolongation; like buprenorphine, its once-daily OUD dose must be split for effective pain relief. Special considerations apply to vulnerable populations, recommending buprenorphine monotherapy or methadone for pregnant patients, while dose titration must proceed cautiously in geriatric patients. Patient progress is monitored using the 5 A's of Analgesia, and essential education includes proper administration techniques and the provision of an opioid reversal agent like naloxone.