Methadone

Drug Data Generic Name Methadone Trade Name Methadose Minimum Dose 15 mg PO once daily Maximum Dose 20 mg PO q6-8 hr

Classification Pharmacologic Class Opioid agonists Therapeutic Class Opioid analgesics Pregnancy Risk Factor C

Contents Methadone Availability and color - Tablets: 5, 10 mg - Dispersible tablets: 40 mg - Oral solution: 5 mg/ 5 mL, 10 mg/ 5 mL - Oral concentrate: 10 mg/mL

Mechanism of Action Binds to opiate receptors in the CNS. Alters the perception of and response to painful stimuli, while producing generalized CNS depression. Pharmacokinetics A: Well absorbed from all sites (50% absorbed following oral administration). D: Widely distributed. Crosses the placenta; enters breast milk. M & E: Mostly metabolized by the liver; some metabolites are active and may accumulate with chronic administration.

Indication General Indications - Severe pain - Suppresses withdrawal symptoms in opioid detoxification

Drug Half Life 15-25 hr

Precaution - Cardiac hypertrophy - Concomitant diuretic use - Hypokalemia - Hypomagnesemia - History of cardiac conduction abnormalities - Concurrent medications affecting cardiac conduction - Other risk factors of arrhythmias - Head trauma - Increased ICP - Severe renal, hepatic, or pulmonary disease - Hypothyroidism - Adrenal insufficiency - Alcoholism - Undiagnosed abdominal pain - Prostatic hyperplasia or ureteral structure - Lactation Drug interaction Drug to drug - Concurrent use laxatives, diuretics, mineralocorticoids may increase risk of hypomagnesemia or hypokalemia and increases risk of arrhythmias - Increase CNS depression with alchohol, antihistamines, and sedatives/hypnotics. - Nevirapine, afevirenz, ritonavir, Phenobarbital, carbamezepine phenytoin, and rifampin may increase metabolism and decrease analgesia; withdrawal may occur. - Kava kava, valerian, or chamomile, can increase CNS depression. Drug to food - none reported

Routes of administration Oral Intramuscular Subcutaneous

Source: Deglin & Vallerand: 2009. Davis’s Drug Guide for Nurses. 11th edition. Pp. 795-796

Contraindications Concentrations - Hypersensitivty - Known alcohol intolerance - Concurrent MAO inhibitor therapy

Source: Deglin & Vallerand: 2009. Davis’s Drug Guide for Nurses. 11th edition. Pp. 795-796

Source: Deglin & Vallerand: 2009. Davis’s Drug Guide for Nurses. 11th edition. Pp. 795-796

Source: Deglin & Vallerand: 2009. Davis’s Drug Guide for Nurses. 11th edition. Pp. 795796

Source: Deglin & Vallerand: 2009. Davis’s Drug Guide for Nurses. 11th edition. Pp. 795-796

Adverse Reaction CNS: Confusion, sedation, dizziness, dysphoria, euphoria,floating, feeling, hallucinations, headache, unusual dreams EENT: Blurred vision, diplopia, miosis Respiratory: Respiratory depression CV: Hypotension, bradycardia, QT prolongation, Torsades de Pointes GI: Constipation, nausea, vomiting GU: Urinary retention Dermatologic: Flushing, sweating Miscellaneous: Physical dependence, psychological dependence, tolerance

Source: Deglin & Vallerand: 2009. Davis’s Drug Guide for Nurses. 11th edition. Pp. 795796

Nursing Responsibilities Before - Observe 15 rights in drug administration. - Assess for hypersensitivity and other contraindications. - Assess type, location, and intensity of pain prior to administration. - Assess blood pressure, pulse, and respirations before and periodically during administration. - Assess bowel function routinely. Prevention of constipation should be instituted if opioid use exceeds 2-3 days/ During - Dispersible tablets are to be dissolved and used for detoxification and maintenance treatment only. - Oral doses may be administered with food or milk to minimize GI irritation. - Dilute each dose of 10 mg/mL oral concentrate with at least 30 mL of water or other liquid prior to administration. - IM is the preferred parenteral route for repeated doses. Subcutaneous administration may cause tissue administration. After - Instruct to take drug exactly as prescribed. - Instruct to avoid alcohol. - Instruct to avoid driving or engaging in other dangerous activities of dizziness, drowsiness or vision changes occur. - Caution patient to notify health care professional if signs of overdose occur. - Do proper documetattion.

Source: Deglin & Vallerand: 2009. Davis’s Drug Guide for Nurses. 11th edition. Pp. 795-796