Pharmacology Book

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Methadone for Opioid Dependence

Aka: Methadone for Opioid Dependence
  1. See Also
    1. Opioid Dependency
    2. Methadone in Chronic Pain
  2. Indication: Methadone Management
    1. Minimum age 18 years
    2. Physiologic Criteria for Opioid Dependence for >1 year
  3. Precautions: Overdose
    1. Day 5 is highest risk time period in Methadone initiation
      1. Day 3: Methadone fat stores are saturated
      2. Day 5: Methadone blood levels increase
    2. Lethal Overdose risks
      1. Children with Accidental Ingestion
      2. Concurrent use of Alcohol or Benzodiazepines
    3. Urine Drug Screen may not demonstrate all interacting substances
      1. Methadone may not appear on drug screen (depending on assay)
      2. Buprenophine (partial Opioid agonist)
        1. Used by Drug Abusers as a substitute for Methadone
    4. Overdosage involving Methadone should be observed closely
      1. Methadone is a long acting agent and likely will persist longer than Naloxone (Narcan)
      2. Other undetected substances may have been taken concurrently in Overdose
    5. References
      1. Weinstock et al in Majoewsky (2012) EM:RAP 12(6): 1
  4. Advantages: Methadone Therapy
    1. Cost effective intervention ($4500 per year)
    2. Decreases risk of acquiring infection
      1. HIV Infection
      2. Hepatitis B Infection
      3. Hepatitis C Infection
    3. More effective than short-term interventions
  5. Management: Methadone Dosing
    1. Initial Dose: 20 to 30 mg per day
    2. Reassess dose after 4 to 10 days
    3. Ideal maintenance dose criteria
      1. No overmedication
        1. Euphoria
        2. Sedation
      2. Satisfactory dose
        1. Withdrawal symptoms alleviated
        2. Opioid craving diminished
  6. Management: Acute pain while on Methadone
    1. Tenets
      1. Methadone patients are tolerant to maintenance dose
      2. Patients receive no analgesia from Methadone
    2. Acute Pain Management
      1. Continue Methadone at maintenance dose
      2. Avoid increasing Methadone dose (lasts 6 hours only)
      3. First line: Non-Narcotic Analgesics
        1. Acetaminophen
        2. NSAIDs
      4. Second-line: Short-acting Narcotic Analgesics
        1. Larger and more frequent doses needed
      5. Avoid mixed Opioid agonist-antagonists
        1. Avoid pentazocine (Talwin)
        2. Avoid butorphanol (Stadol)
        3. Avoid nalbuphine (Nubain)
        4. Avoid Buprenorphine
    3. Surgical procedure
      1. Administer half Methadone dose IM before procedure
      2. Administer half Methadone dose IM after procedure
    4. Chronic Pain Management
      1. Chronic Pain Clinic referral
  7. Management: Discontinuing Methadone
    1. Duration of Detoxification Protocol
      1. Short: 30 days
      2. Long: 31 to 180 days
    2. Taper to low dose Methadone (10 mg per day) first
    3. Start Clonidine 0.3 to 0.5 mg qd
    4. Treat adverse effects
      1. Analgesia with non-Narcotics
      2. Diarrhea with Loperamide (Imodium)
      3. Insomnia
  8. Drug Interactions (may require higher Methadone dose)
    1. Rifampin
    2. Phenytoin (Dilantin)
    3. Carbamazepine (Tegretol)
  9. Resources
    1. American Methadone Treatment Association
      1. http://www.americanmethadone.org
    2. National Alliance of Methadone Advocates (NAMA)
      1. http://www.methadone.org
  10. References
    1. Barnett (1999) Addiction 94(4):479-88 [PubMed]
    2. Demaria (1995) Postgrad Med 97(3):83-92 [PubMed]
    3. Krambeer (2001) Am Fam Physician 63(12):2404-10 [PubMed]
    4. Martin (1991) J Psychoactive Drugs 23(2):165-76 [PubMed]

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