4.6 Pain Management in Patients with Substance Use Disorders

Pain Management in Patients with Substance Use Disorders

Neurobiology of Pain & Addiction Intersections

Managing acute or chronic pain in individuals with a Substance Use Disorder (SUD) or those in long-term recovery on Medications for Opioid Use Disorder (MOUD) represents one of the most complex clinical challenges in addiction nursing. Historically, undertreatment of acute pain in this population has been widespread due to clinician stigma, fear of precipitating addiction relapse, or misinterpreting acute pain behaviors as "drug-seeking."

From a neurobiological standpoint, pain and addiction share overlapping neural circuitry in the mesolimbic dopamine pathway, locus coeruleus, and periaqueductal gray matter. Chronic opioid exposure and active SUD induce two distinct neuroadaptations that profoundly alter pain processing:

1. Severe Opioid Tolerance: Down-regulation and desensitization of mu-opioid receptors require significantly higher doses of exogenous opioids to achieve standard analgesic effects.
2. Opioid-Induced Hyperalgesia (OIH): A paradoxical state wherein chronic opioid exposure sensitizes central pain pathways (via NMDA receptor activation and spinal dynorphin release), causing heightened perception of pain in response to normally non-painful or mildly painful stimuli.

Core CARN Ethical Principle: All patients, regardless of substance use history or MOUD status, have a fundamental right to humane, effective, and non-judgmental pain management. Addiction is NOT a contraindication to appropriate acute pain treatment.

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Acute Pain Management in Patients Receiving MOUD

A critical responsibility of the Certified Addictions Registered Nurse is managing acute pain (e.g., emergency surgery, major trauma, acute fracture) in patients stabilized on Methadone or Buprenorphine.

Protocol for Patients Maintained on Methadone

• Rule 1: CONTINUE Baseline Methadone: The patient's daily baseline methadone dose MUST be continued to prevent acute opioid withdrawal and maintain underlying SUD stability. Baseline methadone provides ZERO acute analgesia because its long-term tissue accumulation suppresses withdrawal but no longer provides acute pain relief due to tolerance.
• Rule 2: ADD Short-Acting Opioids for Acute Pain: Treat acute pain by adding short-acting full agonist opioids (e.g., IV morphine, hydromorphone, or oral oxycodone) on a scheduled or PRN basis.
• Rule 3: Use Shorter Dosing Intervals: Because opioid-tolerant patients metabolize short-acting analgesics rapidly, administer short-acting opioids at shorter intervals (e.g., Q3–4H instead of Q6H).
• Rule 4: Split Daily Baseline Methadone (Optional): Dividing the daily methadone dose into 3 or 4 equal doses (e.g., 30 mg Q8H instead of 90 mg Q24H) takes advantage of methadone's 6–8 hour analgesic window.

Protocol for Patients Maintained on Buprenorphine

Buprenorphine's partial agonist properties and extremely high mu-receptor affinity present unique surgical analgesia challenges.

• Strategy A (Continue Buprenorphine & Add High-Affinity Opioids): Continue baseline sublingual buprenorphine (or divide dose TID/QID for analgesia) and add short-acting full agonists (e.g., hydromorphone or fentanyl) titrated to overcome buprenorphine competition for acute pain.
• Strategy B (Temporary Transition to Full Agonists): For major elective surgeries with anticipated severe postoperative pain, coordinate with the prescribing provider to discontinue buprenorphine 24–48 hours preoperatively, bridge with short-acting full agonist opioids, and re-induce buprenorphine once acute pain resolves.

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Multimodal Non-Opioid Analgesic Modalities

To minimize opioid exposure while achieving superior analgesia, multimodal non-opioid pharmacotherapy must serve as the primary foundation of pain management.

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Universal Precautions & Ethical Nursing Advocacy

Applying Universal Precautions in pain management ensures that standardized risk-mitigation strategies are utilized for ALL patients, reducing clinician bias and preventing stigmatization.

Standard Risk Mitigation Tools

1. Prescription Drug Monitoring Program (PDMP): Check state PDMP database prior to initiating controlled substances to verify active prescriptions and prevent adverse drug interactions.
2. Urine Drug Screening (UDS): Conduct routine non-punitive UDS to confirm presence of prescribed medications and detect unprescribed substances.
3. Patient-Provider Pain Agreements: Utilize clear, written agreements outlining medication storage, refill policies, single-prescriber rules, and treatment goals.
4. Objective Pain & Functional Scoring: Utilize validated pain tools that assess function rather than subjective ratings alone (e.g., Brief Pain Inventory, PEG Scale: Pain, Enjoyment, General activity).
5. Naloxone Co-Prescribing: Always co-prescribe intranasal naloxone when prescribing opioids to patients with a history of SUD or elevated overdose risk.