The nurse is caring for a pregnant client with preeclampsia who is receiving IV magnesium sulfate. The nurses assess the following symptoms: Respiratory rate of 10 breaths/min Urine output 25ml during the last hour Absent deep tendon reflexes What medication should the nurse prepare to administer?

A. Hydralazine is incorrect because it is an antihypertensive used to lower blood pressure in preeclampsia or eclampsia, but it does not reverse magnesium sulfate toxicity, which is the immediate concern given the symptoms of respiratory depression, oliguria, and absent deep tendon reflexes. B. Methylergonovine is incorrect because it is a uterotonic used to control postpartum hemorrhage. It is not indicated for magnesium toxicity and would not address the life-threatening respiratory and neuromuscular effects of magnesium sulfate overdose. C. Calcium gluconate is correct because it is the antidote for magnesium sulfate toxicity. Symptoms of toxicity include respiratory depression (RR <12), oliguria (<30 mL/hr), absent deep tendon reflexes, and eventually cardiac arrhythmias or arrest. Administering 10 mL of 10% calcium gluconate IV over 3–5 minutes can rapidly reverse neuromuscular and cardiac effects while supportive care (e.g., stopping magnesium infusion and monitoring) is continued. D. Narcan is incorrect because it is an opioid antagonist used to reverse opioid overdose. It has no effect on magnesium sulfate toxicity and would not address the neuromuscular or respiratory compromise in this patient.