The antidote for magnesium sulphate in eclampsia?

KPSC Staff Nurse - 2015

Pharmacology

Easy

Appeared in: KPSC Staff Nurse - 2015

Explanation

Calcium gluconate is the specific pharmacological antidote for magnesium sulfate toxicity.
It works by directly antagonizing the effects of magnesium at the neuromuscular junction and on the heart, thereby reversing respiratory depression and cardiac conduction defects.
The standard emergency dose is 1 gram (10 mL of a 10% solution) administered slowly via IV push.
Its rapid action makes it the treatment of choice for life-threatening symptoms of hypermagnesemia, such as respiratory arrest or loss of deep tendon reflexes.

Option B: Sodium chloride is an isotonic crystalloid solution used for fluid resuscitation and hydration. It does not have any properties that counteract the effects of magnesium.
Option C: Calcium carbonate is an oral calcium supplement, commonly used as an antacid (e.g., Tums) or to treat chronic hypocalcemia. It is not formulated for intravenous use and is too slow-acting for an emergency like magnesium toxicity.
Option D: Sodium bicarbonate is an alkalinizing agent used to correct severe metabolic acidosis or to treat specific poisonings (e.g., tricyclic antidepressants, salicylates). It does not reverse the effects of magnesium.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Antidote for Magnesium Sulfate Toxicity as background academic context rather than a clinical decision trigger.
It is a critical patient safety standard to have a vial of calcium gluconate and resuscitation equipment readily available at the bedside for any patient receiving a magnesium sulfate infusion.
Nurses administering magnesium sulfate must perform frequent assessments (typically hourly) of respiratory rate, deep tendon reflexes, and urine output to detect toxicity early.
The first sign of impending magnesium toxicity is often the loss of deep tendon reflexes (e.g., the patellar reflex).

How to Approach the Question

First, identify the core of the question. It asks for the specific antidote for a common obstetric medication, magnesium sulfate.
Recognize this as a factual recall question based on essential pharmacology knowledge for nursing.
Recall the therapeutic use of magnesium sulfate in eclampsia (seizure prevention) and its potential for toxicity.
Think about the signs of magnesium toxicity: central nervous system depression, respiratory depression, and loss of deep tendon reflexes.
Evaluate the options provided. Calcium gluconate is the classic, well-established antagonist for magnesium.
Eliminate the other options based on their primary uses: Sodium chloride is for hydration, calcium carbonate is an oral supplement, and sodium bicarbonate is for acidosis.

Concept Tested & Keywords

QrdjIpuj32LGRHmS426UnA

E6 Obstetrics Williams p. 32-52

E6 Ghai Essential Pediatrics(pp 26-904 of 913) p. 67-69

E6 Pharmacology Nursing Lilley 11e Part 3 p. 212-214