Morphine: Themost potent of the narcotic analgesics - Gafacom (For health. For knowledge)

Morphine: Themost potent of the narcotic analgesics

Group: opioid analgesic
Injection: 10 mg (sulfate or hydrochloride) in 1-ml ampoule
Oral solution: 10 mg (sulfate or hydrochloride) in 5 ml
Tablet: 10 mg (sulfate or hydrochloride)
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General information

Morphine is the principal alkaloid of opium. It is the most potent of the narcotic analgesics and a dangerous drug of addiction. Its supply is controlled under Schedule 1 of the Single Convention on Narcotic Drugs, 1961. It is extensively absorbed following oral administration but parenteral administration produces a more reliable and more rapid response. The plasma half-life is 2-3 hours. It is largely metabolized in the liver and subsequently excreted in the urine.

Clinical information

• Preoperative management of musculoskeletal and visceral pain.
• Premedication prior to general surgery.
• An adjunct to inhalational and other anaesthetic agents during major surgical interventions.
• Postoperative analgesia.

Shortness of breath

Morphine is beneficial in reducing the symptom of shortness of breath due to both cancer and non-cancer causes. In the setting of breathlessness at rest or on minimal exertion from conditions such as advanced cancer or end-stage cardio-respiratory diseases, regular, low-dose sustained-release morphine significantly reduces breathlessness safely, with its benefits maintained over time.

Opioid use disorder

Morphine is also available as a slow-release formulation for opiate substitution therapy (OST) in Austria, Bulgaria, and Slovenia, for addicts who cannot tolerate either methadone or buprenorphine. Two capsules (5 mg  and 10 mg) of morphine sulfate

Dosage and administration

Adults: 150-200 micrograms/kg i.m. or subcutaneously 1 hour before operation.
Children: 50-100 micrograms/kg as above, to a maximum of 10 mg.
Preoperative analgesia
Adults: 150-200 micrograms/kg i.m. or i.v.
Children: 50-100 micrograms/kg i.m.
During anaesthesia
Adults and children: 100 micrograms/kg i.v. repeated every 40-60 minutes as required.
Postoperative analgesia
Adults: 150-300 micrograms/kg i.m. every 4 hours or, by continuous intravenous infusion, 8-10 mg in 30 minutes, then 2-2.5 mg/hour.
Children: 100-200 micrograms/kg i.m. or subcutaneously repeated as necessary. No more than 10 mg should be administered as a single dose.
Rarely, morphine is administered by epidural or intrathecal injection to provide postoperative analgesia. These procedures should be attempted only by experienced specialist anaesthetists and must be used only when facilities for close monitoring of the patient are available. The preparations used must be free of preservatives.
Morphine should be administered at reduced dosage to patients who are elderly or who have cardiorespiratory disease or renal insufficiency.


Bronchial asthma, emphysema or heart failure secondary to chronic lung disease.
• Increased intracranial pressure, head injury or brain tumour.
• Severe hepatic impairment, adrenocortical insufficiency, hypothyroidism.
• Convulsive disorders, acute alcoholism, delirium tremens.
• Diverticulitis and other spastic conditions of the colon, biliary colic and recent surgery on the biliary tract.
• Use of monoamine oxidase inhibitors within the previous 14 days.


Vital signs must be monitored regularly in the immediate postoperative period when morphine is administered during anaesthesia since respiratory depression may persist for several hours. In addition, marked respiratory depression may occur up to several hours after epidural administration. Facilities for intermittent positive pressure ventilation must therefore be immediately available.
To reduce risk of dependence, opioids should not normally be used for postoperative analgesia for longer than 7 days.

Use in pregnancy

Morphine should be used during pregnancy only when the need outweighs any possible risk to the fetus. Its use during labour may produce respiratory depression in the infant, who may require administration of naloxone, 10 micrograms/kg i.m., immediately after birth.

Adverse effects

Acute dose-related effects include respiratory depression; anorexia, nausea, vomiting and constipation; euphoria, dizziness, drowsiness and confusion; dry mouth and spasm of the urinary and biliary tract; hypotension, bradycardia and palpitations.
Allergic phenomena are uncommon but anaphylactoid reactions have been reported.
Prolonged administration may result in physical dependence.

Drug interactions

Morphine potentiates the effects of other cerebral depressants. Its effect is counteracted by naloxone within 2 minutes.
Sedatives should be withheld if a patient has been given morphine since they may cause restlessness or confusion.


Serious overdosage is characterized by respiratory depression, extreme somnolence progressing to stupor or coma, and pin-point pupils. Cardiovascular collapse and cardiac arrest are terminal events.
Supportive therapy includes mechanically assisted ventilation and administration of pressor drugs and fluids to maintain the circulating blood volume. Except in dependent individuals, in whom specific opioid antagonists induce an intense acute withdrawal reaction, naloxone (200 micrograms i.v.), should be administered, as necessary, at 2-minute intervals.

Morphine tablets, solution and injection should be kept in tightly closed containers and should not be allowed to freeze.
The requirements relating to drugs controlled under Schedule 1 of the Single Convention on Narcotic Drugs should be observed.

Morphine: Themost potent of the narcotic analgesics Morphine: Themost potent of the narcotic analgesics Reviewed by gafacom on May 24, 2019 Rating: 5

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