7.2 Opioid Stewardship & Controlled Substance Compliance

Opioid Stewardship & Controlled Substance Compliance

Opioid stewardship is a fundamental responsibility in Physical Medicine & Rehabilitation (PM&R), balancing effective pain relief and functional restoration against the risks of opioid misuse, physical dependence, addiction, and overdose. Clinicians managing chronic non-cancer pain must adhere to rigorous risk-stratification protocols, federal regulatory frameworks, state Prescription Drug Monitoring Programs (PDMPs), and evidence-based clinical guidelines.

CDC 2022 Clinical Practice Guideline Update

The Centers for Disease Control and Prevention (CDC) updated its Clinical Practice Guideline for Prescribing Opioids for Pain in 2022, expanding recommendations to cover acute, subacute, and chronic pain while replacing rigid thresholds with individualized, patient-centered care.

Core Recommendations & Shift from 2016 Guidelines

1. Non-Opioid First-Line Therapy: Non-pharmacological therapies (e.g., physical therapy, exercise, cognitive behavioral therapy) and non-opioid pharmacotherapies (e.g., NSAIDs, gabapentinoids, SNRIs) are preferred for chronic pain management.
2. Avoid Rigid Dose Cutoffs: Unlike the 2016 guideline, which established hard ceilings (e.g., 90 MME/day), the 2022 update stresses that guidelines should not be used as inflexible prescription limits or justification for forced, rapid tapering.
3. Risks of Abrupt Tapering: Forced or rapid opioid tapering in physically dependent patients is strongly discouraged. Abrupt discontinuation increases the risk of severe opioid withdrawal, acute pain exacerbation, psychological distress, depression, suicidal ideation, and transition to illicit opioids (e.g., illicit fentanyl). Tapering, when clinically indicated, should be gradual (e.g., 10% dosage reduction per month) and conducted with shared decision-making.
4. Dosage Considerations: When initiating opioids for opioid-naïve patients, clinicians should start with the lowest effective dose of immediate-release formulations. Clinicians should carefully evaluate risks and benefits before increasing dosages above 50 MME/day.

Morphine Milligram Equivalents (MME) Calculations

Morphine Milligram Equivalents (MME) represent a standardized metric used to quantify total daily opioid exposure across different opioid formulations. Calculating daily MME allows clinicians to assess overdose risk and maintain safe dosing parameters.

Conversion Multipliers

To calculate total daily MME: $\text{Daily MME} = \text{Total Daily Dose of Opioid (mg)} \times \text{MME Conversion Factor}$

Common conversion multipliers include:

• Morphine: 1.0
• Hydrocodone: 1.0
• Oxycodone: 1.5
• Hydromorphone: 4.0
• Oxymorphone: 3.0
• Fentanyl Transdermal Patch: $2.4 \text{ MME/day per mcg/hr}$ (e.g., a $25 \text{ mcg/hr}$ patch $= 60 \text{ MME/day}$)
• Methadone: Methadone exhibits a non-linear, dose-dependent equianalgesic conversion factor due to its long, variable half-life, lipophilic tissue accumulation, and NMDA receptor antagonism. Conversion factors increase as daily methadone dose increases:
  • 1 to 20 mg/day: Multiplier of 4.0
  • 21 to 40 mg/day: Multiplier of 8.0
  • 41 to 60 mg/day: Multiplier of 10.0
  • $>60 \text{ mg/day}$: Multiplier of 12.0 or higher
  • Methadone also requires baseline and follow-up ECG monitoring due to the risk of QTc prolongation and Torsades de Pointes.

Clinical Risk Stratification by MME

• < 50 MME/day: Lower baseline risk of overdose.
• ≥ 50 MME/day: Overdose risk doubles compared to $<20 \text{ MME/day}$; warrants increased clinical monitoring, re-evaluation of treatment goals, and naloxone co-prescribing.
• ≥ 90 MME/day: Overdose risk increases dramatically (up to 10-fold); requires specialist pain consultation and documented justification.

Prescription Drug Monitoring Programs (PDMP)

Prescription Drug Monitoring Programs are state-level electronic databases that track controlled substance prescriptions dispensed by retail pharmacies.

• Mandatory Review: Clinicians must query the PDMP prior to initial controlled substance prescribing and at regular intervals (at least every 3 months or with every refill).
• Key Red Flags: PDMP reports help identify "doctor shopping" (multiple prescribers or pharmacies), dangerous co-prescriptions (specifically concurrent benzodiazepines and opioids, which increase fatal respiratory depression risk four-fold), and early refills indicative of misuse or diversion.

Urine Drug Testing (UDT)

Urine Drug Testing is an objective tool for monitoring adherence, detecting non-prescribed substances, and identifying illicit drug use. UDT should be performed prior to initiating chronic opioid therapy and at least annually (or more frequently based on risk stratification).

Immunoassay vs Confirmation Testing

1. Immunoassay (Screening): Rapid, cost-effective initial test. Uses antibodies to detect drug classes. Subject to false positives (e.g., sertraline or quinolones triggering positive benzodiazepine or opioid screens) and false negatives (synthetic opioids like fentanyl, oxycodone, or buprenorphine may not cross-react with classic opiate immunoassays).
2. Gas Chromatography-Mass Spectrometry (GC-MS) / LC-MS (Confirmation): Highly specific, quantitative definitive testing. Used to confirm immunoassay results, identify specific metabolites, and resolve unexpected results.

Expected Opioid Metabolic Pathways

Interpreting UDT results requires an understanding of hepatic cytochrome P450 and glucuronidative metabolic pathways:

• Codeine $\rightarrow$ metabolizes into Morphine $\rightarrow$ metabolizes into Hydrocodone $\rightarrow$ metabolizes into Hydromorphone.
  • Clinical Pearl: A patient prescribed codeine may expectedly test positive for codeine, morphine, and hydrocodone in low amounts.
• Morphine $\rightarrow$ metabolizes into Hydromorphone (minor metabolite).
• Heroin $\rightarrow$ metabolizes into 6-monoacetylmorphine (6-MAM) $\rightarrow$ metabolizes into Morphine.
  • Clinical Pearl: 6-MAM is specific to heroin and is present in urine for only 2 to 8 hours after consumption.
• Oxycodone $\rightarrow$ metabolizes into Oxymorphone.
• Hydrocodone $\rightarrow$ metabolizes into Hydromorphone.

Expected vs Unexpected Results

• Expected Drug Absent: Indicates non-adherence, drug hoarding, diversion, or rapid metabolism.
• Non-Prescribed Opioid / Illicit Drug Present: Presence of illicit substances (cocaine, methamphetamine, non-prescribed fentanyl, 6-MAM) indicates high-risk behavior requiring clinical intervention, addiction medicine referral, and structured restructuring of the treatment plan.

Naloxone Co-Prescribing & Risk Mitigation

Naloxone is a competitive mu-opioid receptor antagonist that rapidly reverses opioid-induced respiratory depression.

• Indications for Co-Prescribing: Clinicians should co-prescribe naloxone to any patient receiving opioids who has:
  1. Daily dosage exceeding 50 MME/day.
  2. Concurrent benzodiazepine or sedative co-prescription.
  3. History of substance use disorder or prior opioid overdose.
  4. Underlying respiratory comorbidities (e.g., COPD, severe obstructive sleep apnea).
• Patient-Prescriber Agreements (PPA): Documented agreements establishing expectations regarding single-prescriber compliance, single-pharmacy use, mandatory UDT, pill counts, and safe storage.