Class: Opioid Analgesic. C-II
Dosage Forms. Tablet: 5 mg, 10 mg; Tablet for Suspension: 40 mg; Solution: 5 mg/5 mL, 10 mg/5 mL, 10 mg/1 mL
Common FDA Label Indication, Dosing, and Titration.
1. Pain, chronic (moderate-severe): Opioid naive patients, 2.5 mg po q8h, may titrate to response
2. Drug detoxification, opioid abuse: 15-30 mg po q8h, titrate to response; when used for treatment of opioid addiction (detoxification or maintenance), may only be dispensed by certified opioid treatment programs
Off-Label Uses. None
MOA. Methadone is a phenylheptylamine opioid agonist qualitatively similar to morphine but with a chemical structure unrelated to the alkaloid-type structures of the opium derivatives. Analgesic activity of (R)-methadone is 8-50 times that of (S)-methadone, and (R)-methadone has a tenfold higher affinity for opioid receptors.
Drug Characteristics: Methadone
Medication Safety Issues: Methadone
Drug Interactions: Methadone
Adverse Reactions: Methadone
Efficacy Monitoring Parameters. Relief of pain. Relief of signs and symptoms associated with narcotic addiction.
Toxicity Monitoring Parameters. Seek medical attention if severe skin rash, excessive drowsiness, decreased breathing, severe constipation, chest pain, or dizziness; vital signs.
Key Patient Counseling Points. Use a stool softener and stimulant combination or laxative for preventing constipation. May cause drowsiness; avoid driving or other tasks requiring motor coordination. Avoid alcohol and other CNS depressants. Seek medical attention if short of breath or extremely drowsy.
Clinical Pearls. Tolerance and physical dependence may occur with chronic use; avoid abrupt discontinuation. High interpatient variability in absorption, metabolism, and relative analgesic potency of methadone requires careful dose initiation and titration. Fatal respiratory depression has occurred; the highest risk is at initiation and with dosage increases. For oral administration only; excipients to deter use by injection are contained in tablets. Do not chew or swallow tablet for suspension—dissolve in liquid and drink. Keep away from children and pets. Medication guide required at dispensing.