Morphine
Brand Name: Astramorph PF, Avinza, Duramorph, Kadian, Roxanol, MST Continus
Classification: Opioid Analgesic
Indications
- Severe pain (pain in sickle cell crisis, pain associated with surgery preoperatively and postoperatively, pain associated with trauma, cancer, renal colic, ureterolithiasis)
- Pulmonary edema
- Pain associated with myocardial infarction (MI)
- Adjunct to general anesthesia
Mechanism of Action
Morphine binds to opiate receptors in the central nervous system (CNS). Through this mechanism, the perception and response to painful stimuli is altered and a generalized CNS depression will also be produced.
Contraindication
- Hypersensitivity
- Concurrent administration of MAOIs
Use Cautiously in clients with the following condition:
- Head trauma
- Increased intracranial pressure
- Hypothyroidism
- Adrenal insufficiency
- Respiratory depression
- Obstructive airways disease
- Acute hepatic disease
- History of substance abuse
- Geriatric or debilitated clients
- Undiagnosed abdominal pain
- Prostatic hypertrophy
- Patients undergoing procedures that rapidly decrease pain such as cordotomy and radiation
- Pregnancy
- Lactation
Side Effects
- Confusion
- Sedation
- Floating feeling
- Hallucinations
- Headache
- Unusual dreams
- Blurry vision
- Bradycardia
- Constipation
- Nausea and vomiting
- Flushing
- Itching
- Physical dependence
- Psychological dependence
- Tolerance
Overdosage
Symptoms of overdosage
- Pinpoint pupils
- Respiratory depression
- Hypotension
- Circulatory failure (severe cases)
- Deepening coma (severe cases)
Management of overdosage
- Antidote: Naloxone (Narcan) 0.4 mg IV administration, repeated at 2-3 minute intervals as necessary or by an infusion of 2 mg in 500 ml of normal saline or 5% dextrose.
- Empty the stomach. A 0.02% aqueous solution of potassium permanganate may be used for lavage.
- Assist respirations (O2).
- Maintain fluid and electrolyte levels.
Dosage
MST Continus Tablets should be used twice daily at 12-hour interval. The dosage is dependent on the severity of pain and the patient’s previous history of analgesic requirements.
PO, Rect (Adults weighing 50 kilograms or more)
Usual starting dose for moderate to severe pain in opioid-naïve patients: 30 mg every 3-4 hours initially or once 24-hour opioid requirement is determined convert to controlled, extended or sustained-release morphine by administering total daily oral morphine dose every 24 hours (as Kadian or Avinza).
PO, Rect (Adults and Children <50 kgs)
Usual starting dose for moderate to severe pain in opioid-naïve patients – 0.3 mg/kg every 3-4 hours initially.
IV, Subcut (Adults)
Continuous infusion – 0.8-10 mg/hour which may be preceded by a bolus of 15 mg (infusion rates vary greatly up to 400 mg/hr have been used).
IT (Adults): 0.2 -1 mg
Nursing Implications
Assessment
- Pain assessment 1 hour prior to and following administration for PO, IM, subcut and 20 minutes for IV administration.
- Assess for signs and symptoms of overdosage. (listed above)
- Assess bowel function routinely.
Interventions
- Administer 2.5-15 mg over 4-5 minutes. Rapid administration mat lead to increased respiratory depression, hypotension and circulatory collapse.
- PO doses may be administered with food or milk to minimize GI irritation.
- The drug should be discontinued gradually to prevent withdrawal symptoms after a long-term use.
- Increase fluid intake to manage constipation.
