The antidote of magnesium sulfate is:

BHU NO-2019

Pharmacology

Easy

Appeared in: BHU NO-2019

Explanation

Calcium gluconate is the specific pharmacological antidote for magnesium sulfate toxicity.
It works by directly antagonizing the neuromuscular and cardiovascular depressant effects of hypermagnesemia.
Administered intravenously, it rapidly restores normal function and is preferred over calcium chloride due to being less caustic to veins.
The loss of deep tendon reflexes is an early sign of magnesium toxicity, which necessitates stopping the infusion and preparing the antidote.

Option B: Nalorphine hydrochloride is an opioid antagonist, similar to naloxone. Its purpose is to reverse the effects of opioid overdose, not magnesium toxicity.
Option C: While calcium chloride also provides calcium to counteract magnesium, it is highly irritating (caustic) to the veins and carries a significant risk of tissue necrosis if extravasation (leakage) occurs. Therefore, it is not the preferred antidote.
Option D: Diazepam is a benzodiazepine, which is a central nervous system (CNS) depressant. Administering it to a patient with magnesium toxicity would worsen the existing respiratory depression and sedation, potentially leading to respiratory arrest.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacology: Antidotes for Drug Toxicity as background academic context rather than a clinical decision trigger.
A nurse's primary responsibility when administering IV magnesium sulfate is to monitor for signs of toxicity, such as loss of deep tendon reflexes, respiratory depression (rate less than 12/min), and decreased urine output (less than 30 mL/hr).
Recognizing toxicity early, immediately stopping the infusion, and notifying the provider are critical patient safety actions. The nurse must ensure that calcium gluconate is readily available at the bedside as a safety precaution.
What if? If a patient showing signs of magnesium toxicity has no IV access or the current IV has infiltrated, the priority is to stop the magnesium infusion first, then establish a new, patent IV line immediately to administer the calcium gluconate. Delaying the antidote can lead to cardiac or respiratory arrest.

How to Approach the Question

This is a direct factual recall question from pharmacology.
First, identify the key drug mentioned in the question stem: 'magnesium sulfate'.
Next, identify the core concept being asked: its 'antidote'.
Recall the specific antidote for magnesium sulfate toxicity from your knowledge of emergency medications.
Evaluate the options provided. Calcium gluconate is the standard, specific antidote.
Differentiate it from the other options by recalling their drug classes and primary uses (opioid antagonist, another form of calcium, benzodiazepine).

Concept Tested & Keywords

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