Morphine Pharmacology and Toxicity

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Questions and Answers

What is a common adverse effect of morphine?

Tachycardia

Constipation (correct)

Diarrhea

Hypertension

What is the specific antidote for morphine poisoning?

Methadone

Naltrexone

Naloxone (correct)

Nalbuphine

What is a major limitation in the use of morphine?

Constipation

Abuse liability (correct)

Respiratory depression

Hypertension

What is a characteristic of withdrawal symptoms in dependent subjects?

Marked drug seeking behaviour Signup and view all the answers

What is a serious toxicity manifestation of acute morphine poisoning?

Shallow and occasional breathing Signup and view all the answers

What should be done to remove unabsorbed morphine in acute poisoning?

Gastric lavage with pot.permanganate Signup and view all the answers

What happens to blood pressure in hypovolaemic patients who walk about after morphine administration?

It falls Signup and view all the answers

What is a complication that may occur at terminal stages of acute morphine poisoning?

Pulmonary edema Signup and view all the answers

Which of the following physical manifestations is NOT typically associated with morphine withdrawal?

Hypotension Signup and view all the answers

Morphine is contraindicated in patients with head injury due to its potential to:

Increase intracranial pressure Signup and view all the answers

Which of these is a potential complication of morphine use in patients with bronchial asthma?

Bronchospasm Signup and view all the answers

Which of the following is NOT a risk factor for increased sensitivity to morphine?

Hypertension Signup and view all the answers

What is the primary aim of treatment for morphine addiction?

Gradual withdrawal with methadone substitution Signup and view all the answers

Which of the following groups is particularly susceptible to the respiratory depressant effects of morphine?

Infants and the elderly Signup and view all the answers

What is the most important consideration when administering morphine to a patient with respiratory insufficiency?

Closely monitoring respiratory function Signup and view all the answers

Which of the following drugs can potentiate the effects of morphine?

Benzodiazepines Signup and view all the answers

What possible effect does Tramadol have compared to morphine in terms of respiratory depression?

Tramadol causes less respiratory depression than morphine. Signup and view all the answers

Which opioid is indicated for prompt administration during myocardial infarction to alleviate apprehension?

Morphine Signup and view all the answers

What common side effect is experienced with codeine usage?

Constipation Signup and view all the answers

What aspect of morphine or pethidine is important for balanced anaesthesia?

They enhance the analgesic effects of other agents. Signup and view all the answers

How does the analgesic effect of codeine compare to that of aspirin?

60 mg of codeine is roughly equivalent to 600 mg of aspirin. Signup and view all the answers

What is a notable difference in side effects between Tramadol and morphine?

Morphine has a higher risk of urinary retention than Tramadol. Signup and view all the answers

Which opioid is less potent and cannot relieve severe pain effectively?

Codeine Signup and view all the answers

Which of the following best describes the duration of effects for Tramadol?

4-6 hours Signup and view all the answers

Study Notes

Morphine - Adverse Effects

Common adverse effects include sedation, lethargy, and mental clouding.
Occasional vomiting occurs in patients lying down; constipation is prevalent.
Respiratory depression and blurring of vision can be serious complications.
Urinary retention is particularly concerning in elderly males.
Blood pressure may decrease, especially in patients with low blood volume or while moving.
Allergic reactions may manifest as urticaria, itching, or swelling of lips.

Acute Morphine Poisoning

In non-tolerant adults, 50 mg intramuscularly can lead to significant toxicity.
Symptoms include stupor/coma, shallow breathing, cyanosis, pinpoint pupils, and potential convulsions.
Pulmonary edema may occur in terminal stages; death typically results from respiratory failure.
Treatment involves respiratory support, intravenous fluids, vasoconstrictors, and gastric lavage with potassium permanganate.
Naloxone (0.4–0.8 mg IV) is the specific antidote, administered every 2–3 minutes until respiration restores.

Morphine - Tolerance and Dependence

Morphine and related opioids can lead to high degrees of tolerance and abuse potential.
Psychological and physical dependence is pronounced; medically supervised use rarely leads to abuse.
Withdrawal symptoms include anxiety, sweating, tremors, abdominal pain, and rapid weight loss.
Treatment includes the gradual withdrawal of morphine, potentially substituting with long-acting methadone, though relapse risk is high.

Precautions, Contraindications, and Interactions

Caution is necessary in infants and elderly, who are more susceptible to respiratory depression.
Risk factors include respiratory insufficiency, head trauma, hypotensive states, and urinary retention in elderly males.
Patients with hypothyroidism and liver/kidney diseases may exhibit increased sensitivity to morphine.
Unstable personalities may be prone to addiction.
Concomitant use with phenothiazines and tricyclic antidepressants can enhance morphine's effects.

Morphine - Dosing

Typical adult oral dose ranges from 10 to 50 mg; injectable doses are 10-15 mg (IM/SQ) or 2-6 mg IV.
Pediatric dosage is approximately 0.1-0.2 mg/kg for IM/SQ administration.

Codeine

A naturally occurring derivative of morphine, often used as a less potent analgesic (1/10th the potency of morphine).
Comparable analgesic effects to aspirin; effective cough suppressant at subanalgesic doses.
Well absorbed orally, with an action duration of approximately 4-6 hours.
Side effects are generally mild, with constipation as a notable adverse effect.

Tramadol

A centrally acting analgesic with a dual mechanism of action, including opioid pathways.
Comprehensive oral bioavailability; effects last between 4-6 hours with a half-life of 3-5 hours.
Causes fewer gastrointestinal and respiratory side effects compared to morphine.
Common side effects include dizziness, nausea, and mild hemodynamic effects.
The usual dosing range is 50-100 mg orally, IM, or via slow IV infusion, with pediatric dosing of 1-2 mg/kg.

Opioids - Clinical Uses

Primarily indicated for severe pain management, especially in traumatic, visceral, and burn pain scenarios.
Limited use in dentistry as they mainly provide symptomatic relief without addressing underlying issues.
Morphine and pethidine are utilized in preanaesthetic settings for select patients.
Key components of balanced anaesthesia and surgical analgesia include opioids like fentanyl, morphine, or pethidine.

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Test your knowledge on the pharmacological effects and toxicity of morphine, including its adverse effects, antidotes, and withdrawal symptoms.