What is the antidote for magnesium sulfate?

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Explanation

Calcium gluconate is the specific and direct antidote for magnesium sulfate toxicity.
It works by antagonizing the effects of magnesium at the neuromuscular junction and on cardiac muscle, thereby restoring normal function.
Intravenous administration of calcium gluconate can rapidly reverse life-threatening symptoms of hypermagnesemia, such as respiratory depression and cardiac arrest.

Option A: Protamine sulfate is the antidote for heparin, an anticoagulant. It has no role in treating magnesium toxicity.
Option C: Calcium carbonate is an oral calcium supplement and antacid. It is not used for the acute, intravenous treatment of magnesium toxicity due to its formulation and slower onset.
Option D: Sodium bicarbonate is an alkalinizing agent used to treat metabolic acidosis, hyperkalemia, or certain drug overdoses (e.g., tricyclic antidepressants). It does not counteract the effects of magnesium.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacology: Antidotes and Drug Toxicity as background academic context rather than a clinical decision trigger.
Nurses must be able to recognize the early signs of magnesium toxicity (e.g., loss of deep tendon reflexes, lethargy) in patients receiving magnesium sulfate, particularly in obstetric settings for pre-eclampsia management.
Prompt identification and immediate cessation of the magnesium infusion, followed by the administration of calcium gluconate, are critical nursing actions to prevent respiratory or cardiac arrest.
What if? If the patient has severe renal impairment, the risk of magnesium toxicity is significantly higher because magnesium is cleared by the kidneys. The nurse must monitor these patients even more closely and anticipate the need for a lower dose or alternative treatments.

How to Approach the Question

Identify the core of the question: It asks for the specific antidote for the drug magnesium sulfate.
Recognize this as a factual recall question common in pharmacology.
Access your knowledge base of common emergency drugs and their specific antidotes.
Systematically evaluate each option: Protamine sulfate is for heparin, Calcium carbonate is an oral supplement, and Sodium bicarbonate is for acidosis.
Confirm that Calcium gluconate is the established pharmacological antagonist for magnesium.
Select Calcium gluconate as the correct answer based on this direct pharmacological relationship.

Concept Tested & Keywords

Q7_BPZyiP0-zc2kc1BYkC5

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 1 p. 157-159

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

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

Practise the full RUHS, Jaipur, M.Sc Nursing Entrance Exam-2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.