What are the most effective pain management options for patients being treated for Substance Use Disorder (SUD)?

Pain Management for Patients with Substance Use Disorder

For patients with SUD being treated with opioid agonist therapy (methadone or buprenorphine), continue their maintenance dose without interruption and add scheduled short-acting opioids at higher doses and shorter intervals than used for opioid-naïve patients, combined with aggressive non-opioid analgesics. 1, 2

Initial Assessment and Stabilization

Verify the patient's current maintenance therapy dose with their prescribing provider or program before initiating any pain management plan. 1 This is critical because:

• Patients on methadone or buprenorphine have developed significant opioid tolerance and cross-tolerance to other opioids 1
• Undertreating pain can lead to decreased responsiveness to subsequent opioid analgesics 1
• The presence of addiction worsens pain perception through withdrawal syndromes, intoxication, sympathetic arousal, and affective changes 3

Reassure patients explicitly that their addiction treatment will continue uninterrupted and that their pain will be aggressively treated. 1, 2 This decreases anxiety and improves cooperation with the treatment plan.

Multimodal Analgesic Strategy

Non-Opioid Foundation

Start with acetaminophen 650 mg every 4-6 hours (maximum 4-6 grams daily) and/or NSAIDs as the foundation. 3

• Continue these agents even after opioid initiation if they provide additional analgesia and are not contraindicated 3
• For NSAIDs, provide gastroprotection when used long-term 3
• Monitor baseline and every 3 months: blood pressure, BUN, creatinine, liver function studies, CBC, and fecal occult blood 3

Opioid Management for Patients on Methadone

Continue the patient's usual daily methadone dose for maintenance of their opioid dependence. 3, 2 The methadone maintenance dose does NOT provide analgesia for acute pain.

Add short-acting opioids (morphine, hydromorphone, or oxycodone) for pain control:

• Use scheduled dosing at fixed intervals, not PRN (as-needed) 1, 2
• Prescribe at higher doses and more frequent intervals than for opioid-naïve patients due to cross-tolerance 3, 1, 2
• Start with immediate-release formulations to establish effective dosing with early assessment and frequent titration 3
• For breakthrough pain, prescribe immediate-release opioids at 5-20% of the daily morphine equivalent dose 3

Alternative methadone dosing strategy: Split the daily methadone dose into 6-8 hour intervals (adding 5-10% to the current dose for afternoon and evening doses, resulting in 10-20% total increase) to leverage methadone's shorter analgesic effect (6-8 hours) compared to its longer half-life. 2

Opioid Management for Patients on Buprenorphine

Continue buprenorphine maintenance therapy and add short-acting full opioid agonists. 3

• Buprenorphine's partial agonist properties and high receptor affinity may complicate acute pain management 3
• Higher doses of full agonist opioids may be required to overcome buprenorphine's receptor occupancy 3
• Collaborate with palliative care, pain, and/or substance use disorder specialists to determine the optimal approach 3

Critical Medication Avoidance

Never use mixed agonist-antagonist opioids (pentazocine, nalbuphine, butorphanol) as they can precipitate acute withdrawal syndrome. 1, 2

Avoid tramadol and codeine in this population:

• Both are prodrugs with limitations in dose titration 3
• Tramadol has a low threshold for neurotoxicity and significant drug interactions 3
• Codeine requires CYP2D6 metabolism to achieve analgesic effects 3

Avoid fixed-dose combination products containing acetaminophen when high opioid doses are required due to hepatotoxicity risk. 2

Adjuvant Analgesics

Add tricyclic antidepressants or other adjuvants that potentiate opioid effects. 1, 2

Monitoring and Safety

Monitor frequently for:

• Level of consciousness and respiratory rate 2
• Signs of opioid toxicity or overdose 3
• Have naloxone immediately available 2

Establish clear treatment agreements regarding:

• Number of pills dispensed 1
• Frequency of use 1
• Expected duration of treatment 1
• Single provider/pharmacy when appropriate 3

For hospitalized patients, consider patient-controlled analgesia (PCA) to minimize anxiety about pain management. 1, 2

Communication and Coordination

Inform the methadone clinic or prescribing physician of the patient's admission, discharge, and all medications administered. 2

Common Pitfalls to Avoid

Do not undertreat pain due to "opiophobia" - exaggerated fears of addiction, diversion, or side effects. 3, 1, 2 Inadequate pain treatment is suboptimal medical care and particularly harmful in this population.

Do not misinterpret drug-seeking behaviors as active addiction when they may represent:

• Pseudoaddiction (seeking relief from uncontrolled pain) 1
• Therapeutic dependence (fear of pain or withdrawal) 1

Do not allow pain to reemerge before administering the next scheduled dose - this causes unnecessary suffering and increases tension between patient and treatment team. 1, 2

Do not confuse physical dependence and tolerance (predictable physiologic consequences of opioid exposure) with substance dependence (loss of control, continued use despite harm). 3

Special Populations

For patients with renal impairment: rotate to methadone (excreted fecally) if not contraindicated; carefully titrate fentanyl, oxycodone, or hydromorphone; avoid morphine, meperidine, codeine, and tramadol. 3

For patients with hepatic impairment: reduce starting and titration doses by half and monitor closely for toxicity. 4