What is the antidote if magnesium sulfate overdose is suspected?

• A. Calcium gluconate
• B. Calcium chloride
• C. Sodium bicarbonate
• D. Protamine sulfate

Answer: (A)

Calcium gluconate reverses magnesium sulfate toxicity by providing calcium ions that counteract the depressant effects of magnesium on neuromuscular transmission and cardiac conduction. When magnesium is in excess, deep tendon reflexes fade and respiration and heart rate can slow; giving calcium gluconate helps restore normal nerve and muscle function and stabilize the heart. In practice, it’s given intravenously to immediately counteract the overdose, with dosing guided by clinical status and Mg levels. Calcium chloride can be used in some settings but is more irritating to veins, while sodium bicarbonate and protamine sulfate do not address magnesium toxicity.