Morphine

General

• Type: Opiods
• Dosage Forms: 5, 10, 15, 20, 30, 45, 50, 60, 75, 80, 90, 100, 120, 200, 0.5/ml, 1/ml, 2/ml, 4/ml. 5/ml, 8/ml, 10/ml, 15/ml, 25/ml, 50/ml,
• Common Trade Names: Astramorph, AVINza, Duramorph, Infumorph, Kadian, MS contin

Adult Dosing

• Acute pain (Moderate to severe):
  • Oral: 10-30mg q4hr prn
  • IM: 5-15mg q4hr prn
  • IV: 2.5-5mg q3hr prn
    • AMI: 4-8mg q5-15min prn
    • Critically ill: 2-4mg q1-2hr or 4-8mg q3-4hr prn
  • Continuous infusion IV, SC: 0.8-10mg/hr (up to 80mg/hr)
    • Critically ill: 2-30mg/hr
    • PCA 0.5-2.5mg q5-10min prn
  • Epidural (Preservative free)
    • Single dose: 30-100mcg/kg
    • Continuous infusion: 0.2-0.4mg/hr
    • Continuous microinfusion: 3.5-10mg over 24hrs, titrate to effect (max ~30mg)
  • Intrathecal (Preservative free)
    • Single dose: 0.1-03.mg
    • Continuous microinfusion: 0.2-10mg over 24 hours (max ~20mg)
  • Rectal: 10-20mg q3-4hr

Pediatric Dosing

• Children >6months and <50kg
• Acute pain (Moderate to severe)
  • Oral: 0.15-0.3mg/kg q3-4hr prn
  • IM, SC: 0.1-0.2mg/kg
  • IV: 0.05-0.3mg/kg q3-4hr prn (not to exceed 10mg/dose)
  • Continuous infusion: 10-30mcg/kg/hr
  • PCA 0.01-0.03mg/kg/dose and 0-0.03mg/kg/hr

Special Populations

• Pregnancy Rating: C
• Lactation: Enters breast milk
• Renal Dosing
  • CrCl 10-50: 75% of normal dose
  • CrCl <10: 50% of normal dose
  • HD: Child 50%, adult no adjustment
  • PD: Child 50%
  • CRRT: Child and adults 75%
• Hepatic Dosing: No adjustment generally (cirrhosis can consider dose adjustment)

Contraindications

• Allergy to class/drug

Adverse Reactions

Serious

• Circulatory depression, shock, cardiac arrest
• Bradycardia, hypotension
• CNS depression, sedation
• Apnea, respiratory arrest/depression
• Anaphylaxis, laryngospasm

Common

• Dependence
• ADH release, hypogonadism
• Drowsiness, dizziness, confusion, headache
• Pruritis
• Xerostomia, constipation, vomiting
• Urinary retention
• Pancytopenia
• Weakness
• Hypoxia
• Histamine release, urticaria
• Afib, tachycardia, edema, chest pain
• Abdominal pain

Pharmacology

• Half-life: Immediate release 2-4hrs; Avinza 24hrs; Kadian 11-13hrs
• Metabolism: Hepatic
• Excretion: Urine and feces
• Mechanism of Action:
  • Binds to opioid receptors in CNS
  • Inhibits ascending pain pathways
  • Alters perception and response to pain
  • Produces CNS depression

References

• UpToDate

Authors

Ami Yamamoto, Ross Donaldson, Neil Young, Daniel Ostermayer