Classifications: narcotic (opiate) agonist; analgesic; Therapeutic:narcotic (opiate) analgesic
Pregnancy Category: C
Controlled Substance: Schedule II
5 mg, 10 mg, 40 mg tablets; 1 mg/mL, 2 mg/mL, 10 mg/mL oral solution; 10 mg/mL injection
Synthetic narcotic similar to morphine but is orally effective and has longer duration of action. It is a CNS depressant
that causes sedation and respiratory depression. Highly addictive, with abuse potential that matches morphine; abstinence
syndrome develops more slowly, and withdrawal symptoms are less intense but more prolonged.
Relieves severe pain and manages withdrawal therapy from narcotics, especially heroin.
To relieve severe pain; for detoxification and temporary maintenance treatment in hospital and in federally controlled maintenance
programs for ambulatory patients with narcotic abstinence syndrome.
Severe pulmonary disease; COPD; obstetric analgesia; pregnancy (category C).
History of QT prolongation; liver, kidney, or cardiac dysfunction.
Route & Dosage
Adult: PO/SC/IM 2.510 mg q34h prn IV 2.5-10 mg q812h prn (opiate na?ve patient)
Child: PO/IV/SC/IM 0.10.2 mg/kg q4h times 23 doses, then q612h prn (max: 510 mg/dose)
Adult: PO/SC/IM 1540 mg once/d, usually maintained at 20120 mg/d
Clcr <10 mL/min: use 5075% of dose
- Give for analgesic effect in the smallest effective dose to minimize the possible tolerance and physical and psychic dependence.
- Dilute dispersible tablets in 120 mL of water or fruit juice and allow at least 1 min for dispersion.
- Note: IM route is preferred over SC when repeated parenteral administration is required (SC injections may cause local irritation
and induration). Rotate injection sites.
PREPARE: Direct/IV Infusion: May be given undiluted or diluted with 15 mL of NS.
ADMINISTER: Direct/IV Infusion: Give over 5 or more minutes.
INCOMPATIBILITIES Y-site: Phenytoin.
- Store at 15°30° C (59°86° F) in tight, light-resistant containers.
Adverse Effects (≥1%)CNS: Drowsiness,
light-headedness, dizziness, hallucinations. GI:
Nausea, vomiting, dry mouth, constipation. Body as a Whole:
Transient fall in BP, bone and muscle pain. Urogenital:
Impotence. Respiratory: Respiratory depression.
and other cns depressants
add to sedation and CNS
may potentiate CNS
stimulation; with mao inhibitors
, selegiline, furazolidone
causes excessive and prolonged CNS depression
, convulsions, cardiovascular collapse. Food: Grapefruit juice
may increase serum levels and adverse effects. Herbal: St. John's wort
decreases plasma levels.
Well absorbed from GI tract, variable IM absorption. Onset:
3060 min PO; 1020 min IM/SC. Peak:
12 h. Duration:
68 h PO, IM, SC; may last 2248 h with chronic dosing. Distribution:
Crosses placenta; distributed into breast milk. Metabolism:
In liver (CYP3A4). Elimination:
In urine. Half-Life:
Assessment & Drug Effects
- Evaluate patient's continued need for methadone for pain. Adjustment of dosage and lengthening of between-dose intervals
may be possible.
- Monitor respiratory status. Principal danger of overdosage, as with morphine, is extreme respiratory depression.
- Be aware that because of the cumulative effects of methadone, abstinence symptoms may not appear for 3672 h after last
dose and may last 1014 d. Symptoms are usually of mild intensity (e.g., anorexia, insomnia, anxiety, abdominal discomfort,
weakness, headache, sweating, hot and cold flashes).
- Observe closely for recurrence of respiratory depression during use of narcotic antagonists such as naloxone, naltrexone,
and levallorphan to terminate methadone intoxication. Since antagonist action is shorter (13 h) than that of methadone
(3648 h or more), repeated doses for 824 h may be required.
Patient & Family Education
- Be aware that orthostatic hypotension, sweating, constipation, drowsiness, GI symptoms, and other transient adverse effects
of therapeutic doses appear to be more prominent in ambulatory patients. Most adverse effects disappear over a period of
- Make position changes slowly, particularly from lying down to upright position; sit or lie down if you feel dizzy or faint.
- Do not drive or engage in potentially hazardous activities until response to drug is known.