Uses

Pain

• PO: legitimately or illegitimately

Abuse

• IV: addicts dissolve and inject methadone

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Pharmacology

• Long-Acting Opiate Receptor Agonist (see Opiates, Opiates)

Metabolism

• xxx

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Administration

• PO
  • Pre-Treatment EKG: required for determine baseline QT interval
  • Follow-Up EKG at 30 Days: recommended
  • Annual EKG: recommended

Dose Adjustment

• Hepatic
• Renal

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Adverse Effects

Cardiovascular Adverse Effects

Q-T Prolongation with Definite Association with Torsade (see Torsade, Torsade)

• Epidemiology
  • FDA Black Box Warning Related to Risk of Torsade: issued in 2006
  • Most cases of torsade are associated with high methadone doses or recent methadone dose increase
• Clinical:

Gastrointestinal Adverse Effects

Increased Risk of Hepatic Encephalopathy (see Hepatic Encephalopathy, Hepatic Encephalopathy)

• xxxx

Pulmonary Adverse Effects

Acute Lung Injury-ARDS (see Acute Lung Injury-ARDS, Acute Lung Injury-ARDS)

• Epidemiology: has been reported with both PO and IV use
• Treatment: supportive

Respiratory Depression

• Clinical
  • Acute Hypoventilation (see Acute Hypoventilation, Acute Hypoventilation)
  • Chronic Hypoventilation (see Chronic Hypoventilation, Chronic Hypoventilation)

Talc/Foreign Body Granulomatosis (see Foreign Body Granulomatosis, Foreign Body Granulomatosis)

• Epidemiology: associated with intravenous methadone abuse

Toxicologic Adverse Effects

Serotonin Syndrome (see Serotonin Syndrome, Serotonin Syndrome)

• xxxx

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Methadone Intoxication

Clinical

• xxx
• xxx
• xxx

Diagnosis

• Urine Toxicology Screen: methadone can give false-negative urine toxicology screen for opiates

Treatment

• Naloxone (Narcan) (see Naloxone, Naloxone)

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References

• A case of serotonin syndrome associated with methadone overdose. Proc West Pharmacol Soc. 2008;51:42-4 [ MEDLINE]