Morphine Sulfate
This medication is a Schedule II drug.
Common Brand Names: Duramorph, Astramorph/PF
Therapeutic Class: A semi-synthetic phenanthrene-derivative opiate analgesic
Common Injectable Dosage Forms: Injection: In concentrations ranging from 0.5-50 mg/mL in various size containers for use as IM, IV, epidural, or intrathecal administration
Dosage Ranges:
Should be given in the smallest effective dose and frequency in order to minimize the development of tolerance and/or physical dependence. The usual range for SQ or IM doses is 5-20 mg every 4 hours as necessary, with IV doses ranging from 2.5-15 mg every 4 hours.
Children’s doses range from 0.05-0.2 mg/kg IM or IV every 4 hours as necessary with single doses not to exceed 15 mg. Continuous IV infusion has been initiated at 0.8-10 mg/hour and titrated as high as 150 mg/hour to achieve pain control, with pediatric doses ranging from 0.025-2.6 mg/kg/hour.
Epidural analgesia has been achieved with doses of 5-10 mg, and intrathecal dosages are approximately 1/10th the equivalent epidural dose. The routes should only be given by physicians experienced in the respected techniques of administration.
Administration and Stability: Morphine sulfate is given undiluted when administered by the intrathecal and epidural routes. Intravenous administration can be accomplished by mixing with 4-5 mL of Water for Injection and given over a 5-minute period. For continuous infusion, prepare a 0.1-1 mg/mL solution using 5% Dextrose in Water and administer using a controlled-infusion device. pH 3.5-6.5
Pharmacology/Pharmacokinetics: Opiate agonists exert their principal pharmacologic effect on receptors at several systems of neurotransmitters to produce analgesia. However, their precise mechanism of action has not been fully elucidated. The drugs alter the perception of pain at the spinal cord and higher levels in the CNS. They also alter the patient’s emotional response to pain. Onset of action is usually 15-30 minutes and analgesia is maintained for 4-8 hours, depending on the route of administration. Metabolism occurs in the liver by glucuronidation. Excretion in the urine as the conjugate is the primary route of elimination.
Drug and Lab Interactions: Opiates may potentiate the effects of other CNS DEPRESSANTS including other opiate agonists, general anesthetics, tranquilizers, sedatives, hypnotics, alcohol, and other CNS drugs such as MAO inhibitors and tricyclic antidepressants. Opiate agonists may also decrease the effects of diuretics in patients with congestive heart failure.
Contraindications/Precautions: Caution should be used in administering to patients with known hypersensitivity to other opiate agonists. Morphine should also be used with caution in patients with hepatic or renal dysfunction, and also in patients with chronic respiratory problems. Individuals who perform hazardous tasks requiring mental alertness and/or physical coordination should be warned about adverse effects of opiate agonists. Injectable naloxone hydrochloride should be readily available in case of severe adverse reactions. Pregnancy Category C/D.
Monitoring Parameters: Pain relief, respiratory and mental status, and blood pressure
Adverse Effects: Respiratory and/or circulatory depression are the chief hazards to opiate agonist therapy as respiratory arrest, shock, and cardiac arrest have occurred. Other CNS adverse effects include dizziness, sedation, coma, dysphoria. Less serious side effects reported include nausea, vomiting, constipation, changes in biliary tract pressure, and urinary retention. Tolerance, psychological and physical dependence may also occur in patients receiving opiate agonists.
Common Clinical Applications: A strong analgesic used in the relief of severe acute and chronic pain, for preoperative sedation, as supplement to anesthesia, and for analgesia during labor.
