methadone hydrochloride

Drug Name

Generic Name : methadone hydrochloride

Brand Name: Dolophine, Methadone HCl Diskets, Methadone HCl Intensol, Methadose

Classification:  Opioid agonist analgesic

Pregnancy Category C
Controlled Substance C-II 

Dosage & Route

Available forms : Tablets—5, 10 mg; oral solution—5 mg/5 mL, 10 mg/5 mL; oral concentrate—10 mg/mL; injection—10 mg/mL; dispersible tablets—40 mg

Dosages : Oral methadone is approximately one-half as potent as parenteral methadone.

ADULTS
  • Relief of pain: 2.5–10 mg IM, subcutaneously, or PO q 3–4 hr as necessary. IM route is preferred to subcutaneous for repeated doses (subcutaneous use may cause local irritation). Individualize dosage; patients with excessively severe pain and those who have become tolerant to the analgesic effect of opioids may need higher dosage.
  • Detoxification: Initially, 15–20 mg PO or parenteral; PO preferred. Increase dose to suppress withdrawal signs. 40 mg/day in single or divided doses is usually an adequate stabilizing dose for those physically dependent on high doses. Continue stabilizing doses for 2–3 days, then gradually decrease dosage every day or every 2 days. A daily reduction of 20% of the total dose may be tolerated. Provide sufficient dosage to keep withdrawal symptoms at tolerable level. Treatment should not exceed 21 days and may not be repeated earlier than 4 wk after completion of previous course. Detoxification treatment continued longer than 21 days becomes maintenance treatment, which may be undertaken only by approved programs (addicts hospitalized for other medical conditions may receive methadone maintenance treatment).
  • Maintenance treatment: For patients who are heavy heroin users up until hospital admission, initial dose of 20 mg 4–8 hr after heroin is stopped or 40 mg in a single dose PO. For patients with little or no opioid tolerance, half this dose may suffice. Dosage should suppress withdrawal symptoms but not produce acute opioid effects of sedation, respiratory depression. Give additional 10-mg doses if needed to suppress withdrawal syndrome. Adjust dosage, up to 120 mg/day.
PEDIATRIC PATIENTS
  • Not recommended for relief of pain in children due to insufficient documentation.
GERIATRIC PATIENTS OR IMPAIRED ADULTS
  • Use caution. Respiratory depression may occur in the elderly, the very ill, those with respiratory problems. Reduced dosage may be necessary.
Therapeutic actions
  • Methadone is a synthetic opioid mu-agonist which binds to opiate receptors in CNS, decreasing the perception and response to pain. It is used principally as an analgesic and for treatment of opioid addiction.
Indications
  • Relief of severe pain
  • Detoxification and temporary maintenance treatment of opioid addiction (ineffective for relief of general anxiety)
Adverse effects
  • Nausea; vomiting; constipation; anorexia; abdominal pain; drowsiness; respiratory depression; hypotension; bradycardia; euphoria; headache; dysphoria; urinary retention; miosis; visual disturbances; impotence; dizziness; sweating; pruritis; asthenia; arrythmias; QT prolongation.
  • Potentially Fatal: Cardiac arrest; respiratory arrest; shock.
Contraindications
  • Acute respiratory depression; acute bronchial asthma; acute alcoholism; risk of paralytic ileus; raised intracranial pressure or head injury.
Nursing considerations
Assessment
  • History: Hypersensitivity to opioids, diarrhea caused by poisoning, bronchial asthma, COPD, cor pulmonale, respiratory depression, kyphoscoliosis, acute alcoholism, increased intracranial pressure; acute abdominal conditions, CV disease, supraventricular tachycardias, myxedema, seizure disorders, delirium tremens, cerebral arteriosclerosis, ulcerative colitis, fever, Addison’s disease, prostatic hypertrophy, urethral stricture, recent GI or GU surgery, toxic psychosis; pregnancy; labor; lactation
  • Physical: T; skin color, texture, lesions; orientation, reflexes, bilateral grip strength, affect, pupil size; pulse, auscultation, BP, orthostatic BP, perfusion; R, adventitious sounds; bowel sounds, normal output; frequency and pattern of voiding, normal output; ECG; EEG; LFTs, renal and thyroid function tests
Interventions
  • BLACK BOX WARNING: Monitor patient for QT-interval prolongation, especially at higher doses.
  • Give to lactating women 4–6 hr before the next feeding to minimize the amount in milk.
  • WARNING: Keep opioid antagonist and equipment for assisted or controlled respiration readily available during parenteral administration.
  • WARNING: Use caution when injecting subcutaneously into chilled body areas or in patients with hypotension or in shock—impaired perfusion may delay absorption; with repeated doses, an excessive amount may be absorbed when circulation is restored.
Teaching points
  • Take drug exactly as prescribed.
  • Avoid alcohol—serious adverse effects may occur.
  • Do not take leftover medication for other disorders; do not let anyone else take the prescription.
  • Avoid pregnancy while taking this drug; using barrier contraceptives is advised.
  • You may experience these side effects: Nausea, loss of appetite (take with food, lie quietly, eat frequent small meals); constipation (laxative may help); dizziness, sedation, drowsiness, impaired visual acuity (avoid driving, performing other tasks that require alertness, visual acuity).
  • Report severe nausea, vomiting, constipation, shortness of breath, or difficulty breathing.