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methadone hydrochloride eptadone (UK)
Dolophine, Metadol, Methadone HCl Intensol, Methadose, Physeptone (UK), Synastone (UK)
Pharmacologic class: Opioid agonist
Therapeutic class: Analgesic, opioid detoxification adjunct
Controlled substance schedule II
Pregnancy risk category C
FDA Box Warning
• Deaths have occurred during drug initiation for opioid dependence. In some cases, deaths apparently resulted from respiratory or cardiac effects of methadone and too-rapid titration without considering drug accumulation. Make sure you understand drug's pharmacokinetics, and be vigilant during treatment initiation and dosage titration. Caution patients against self-medicating with CNS depressants at start of therapy.
• Prolonged QT intervals and serious arrhythmia (torsades de pointes) have occurred. Most cases involved patients being treated for pain with large, multiple daily doses.
• Federal law requires that when drug is used to treat opioid addiction in detoxification or maintenance programs, it can be dispensed only by treatment programs certified by the Substance Abuse and Mental Health Services Administration and approved by designated state authority. Certified treatment programs must dispense and use drug in oral form only and according to treatment requirements stipulated in Federal Opioid Treatment Standards. Failure to abide by regulations may lead to criminal prosecution, drug seizure, revocation of program approval, and injunction precluding program operation.
Binds to and depresses opiate receptors in spinal cord and CNS, altering perception of and response to pain
Injection: 10 mg/ml
Oral solution: 5 mg/5 ml, 10 mg/5 ml, 10 mg/ml (concentrate)
Tablets: 5 mg, 10 mg
Tablets (dispersible diskettes): 40 mg
⊘Indications and dosages
➣ Opioid detoxification
Adults: Initially, 15 to 20 mg/day P.O. to suppress withdrawal. Additional doses may be necessary if symptoms aren't suppressed or if they reappear. Most patients are adequately stabilized on total daily dosage of 40 mg given in single or divided doses; however, some may need higher dosages. When patient is stable for 2 to 3 days, decrease dosage gradually at 2-day intervals. If patient can't tolerate oral doses, give I.M. or subcutaneously (usually at about 25% of total daily P.O. dosage) in two injections.
➣ To maintain opioid abstinence
Adults: Oral dosage highly individualized based on control of abstinence symptoms without respiratory depression or marked sedation. If patient can't tolerate oral doses, give I.M. or subcutaneously (usually at about 25% of total daily P.O. dosage) in two injections.
➣ Chronic and severe pain
Adults: For chronic pain, 2.5 to 10 mg P.O., I.M., or subcutaneously q 3 to 4 hours as needed; adjust dosage and dosing interval as needed. For severe chronic pain (as in terminal illness), 5 to 20 mg P.O. q 6 to 8 hours.
Children: Dosage individualized.
• Hypersensitivity to drug or other opioid agonists
Use cautiously in:
• head trauma; severe renal, hepatic, or pulmonary disease; hypothyroidism; adrenal insufficiency; undiagnosed abdominal pain; prostatic hypertrophy; urethral stricture; toxic psychosis; Addison's disease; cor pulmonale; increased intracranial pressure; severe inflammatory bowel disease; severe CNS depression; hypercapnia; seizures; fever; alcoholism
• recent renal or hepatic surgery
• elderly or debilitated patients
• pregnant patients, patients in labor, or breastfeeding patients.
• Mix dispersible tablets with 120 ml of water or orange juice, citrus Tang, or other acidic fruit beverage.
• Dilute 10 mg/ml of oral solution with water or other liquid to at least 30 ml. In detoxification and maintenance of opioid withdrawal, dilute solution in at least 90 ml of fluid.
• When used parenterally, I.M. route is preferred. Rotate injection sites.
• For detoxification and maintenance, give oral solution only, to reduce potential for parenteral abuse, hoarding, and accidental ingestion.
• Know that patients who can't take oral drugs because of nausea or vomiting during detoxification or maintenance should be hospitalized and given methadone parenterally.
CNS: amnesia, anxiety, confusion, poor concentration, delirium, delusions, depression, dizziness, drowsiness, euphoria, fever, hallucinations, headache, insomnia, lethargy, light-headedness, malaise, psychosis, restlessness, sedation, clouded sensorium, syncope, tremor, seizures, coma
CV: hypotension, palpitations, edema, bradycardia, shock, cardiac arrest
EENT: visual disturbances
GI: nausea, vomiting, constipation, ileus, biliary tract spasm, gastroesophageal reflux, indigestion, dysphagia, dry mouth, anorexia
GU: urinary hesitancy, urinary retention, prolonged labor, difficult ejaculation, erectile dysfunction
Hematologic: anemia, leukopenia, thrombocytopenia
Musculoskeletal: joint pain
Respiratory: depressed cough reflex, hypoventilation, wheezing, asthma exacerbation, atelectasis, pulmonary edema, bronchospasm, respiratory depression or arrest, apnea
Skin: urticaria, pruritus, flushing, pallor, diaphoresis
Other: allergic reaction, hiccups, facial or injection site edema, pain, physical or psychological drug dependence, withdrawal symptoms
Drug-drug.Amitriptyline, antihistamines, chloral hydrate, clomipramine, glutethimide, methocarbamol, MAO inhibitors, nortriptyline: increased CNS and respiratory depression
Anticholinergics: increased risk of severe constipation leading to ileus
Antiemetics, general anesthetics, phenothiazines, sedative-hypnotics, tranquilizers: coma, hypotension, respiratory depression, severe sedation
Ascorbic acid, phenytoin, phosphate, potassium, rifampin: decreased methadone blood level
Cimetidine, fluvoxamine, protease inhibitors: increased analgesia, CNS and respiratory depression
Diuretics: increased diuresis
Hydroxyzine: increased analgesia, CNS depression, and hypotension
Paregoric, loperamide: increased CNS depression, severe constipation
Naloxone: antagonism of methadone's analgesic, CNS, and respiratory effects
Naltrexone: induction or worsening of withdrawal symptoms (when given within 7 days of methadone)
Neuromuscular blockers: increased or prolonged respiratory depression
Drug-diagnostic tests.Amylase, liver function tests: increased levels
Drug-behaviors.Alcohol use: increased CNS and respiratory depression
• Assess patient for relief of severe, chronic pain requiring around-the-clock dosing. Tailor dosage to patient's pain level and drug tolerance.
• Monitor CNS, respiratory, and cardiovascular status.
• Watch for deepening sedation, which may increase with successive doses.
• Evaluate bowel and bladder function. Give laxatives if appropriate.
• Monitor detoxification treatment closely. Short-term detoxification shouldn't exceed 30 days; long-term detoxification, 180 days.
• Assess patient on maintenance therapy for successful rehabilitation. Know that maintenance therapy should be part of comprehensive treatment plan that includes medical, vocational rehabilitative, employment, educational, and counseling services.
☞ Instruct patient to promptly report severe adverse reactions.
• Tell patient he may take drug with food if GI upset occurs.
• Tell ambulatory patient to change positions slowly to avoid orthostatic hypotension.
☞ Caution patient not to discontinue drug abruptly.
• Advise patient to avoid driving and other hazardous activities, because drug may cause drowsiness or dizziness.
• Tell female patient to inform prescriber if she's pregnant or breastfeeding.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and behaviors mentioned above.