HPSSC - 2015: The pain medication of choice in acute Myocardial Infarction is?

HPSSC - 2015

Pharmacology

Easy

Appeared in: HPSSC - 2015

Explanation

Morphine is a potent opioid analgesic, making it highly effective for the severe pain associated with acute myocardial infarction (MI).
It provides beneficial hemodynamic effects through venodilation, which reduces cardiac preload (the volume of blood returning to the heart).
By reducing preload and afterload, morphine decreases the overall workload of the heart, thereby lowering myocardial oxygen consumption and demand.
It also helps to alleviate anxiety, which blunts the adverse effects of the sympathetic stress response (like tachycardia and hypertension) on the heart.

Option A: Diclofenac is a non-steroidal anti-inflammatory drug (NSAID). NSAIDs are contraindicated in acute MI because they interfere with scar formation and increase the risk of myocardial rupture and other adverse cardiovascular events.
Option B: Codeine is a weak opioid analgesic. The pain of an acute MI is typically severe and requires a much stronger analgesic for effective control.
Option D: Pethidine is generally avoided in MI because it can cause tachycardia (an increased heart rate), which would increase the oxygen demand of the already ischemic myocardium. It is also a less potent analgesic for cardiac pain compared to morphine.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacological Management of Acute Myocardial Infarction Pain as background academic context rather than a clinical decision trigger.
A nurse's primary role is to rapidly assess and manage chest pain in a patient with suspected MI. Prompt administration of morphine can prevent further heart muscle damage.
Patient safety is paramount. The nurse must continuously monitor the patient's respiratory rate, blood pressure, and level of consciousness after giving morphine, as hypotension and respiratory depression are significant risks.
The nurse must have the opioid antagonist naloxone readily available at the bedside as a crucial safety measure to reverse life-threatening respiratory depression if it occurs.

How to Approach the Question

First, identify the core clinical condition in the question: acute Myocardial Infarction (MI).
Next, understand the therapeutic goal: not just pain relief, but also reducing the workload on the damaged heart.
Evaluate each drug option based on its known effects on the cardiovascular system.
Eliminate options that are contraindicated or harmful in MI. NSAIDs like Diclofenac increase cardiovascular risk. Pethidine can cause tachycardia, which is detrimental.
Compare the remaining opioid options. Recognize that MI causes severe pain, requiring a potent analgesic (morphine) over a weak one (codeine).
Select the drug that provides both potent pain relief and favorable hemodynamic effects (decreased cardiac workload), which points directly to morphine.

Concept Tested & Keywords

Q-oxrGmXqGpYR0ook42kW2

E6 Medicine Harrison 22e Part 2 p. 22-24

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 3 p. 48-50

E6 Medicine Davidson Principles Practice 24e p. 1370-1372