Loading dose of MgSo4 in Eclampsia is?

NIMHANS Nursing Officer - 2019

Obstetrics & Gynaecology

Easy

Appeared in: NIMHANS Nursing Officer - 2019

Explanation

The standard loading dose of magnesium sulfate (MgSO₄) for eclampsia is 4 grams, administered intravenously, to rapidly control or prevent seizures.
This initial high dose is crucial for quickly elevating serum magnesium levels to the therapeutic range of 4–7 mEq/L.
Established protocols, such as the Pritchard and Zuspan regimens, both incorporate a 4 g IV loading dose as the initial step in managing eclampsia.

Option B: A microgram (mcg) is one-millionth of a gram. A dose of 4 mcg is infinitesimally small and would have no therapeutic effect on eclamptic seizures. This highlights the critical importance of understanding dosage units.
Option C: A milligram (mg) is one-thousandth of a gram. A 10 mg dose is 400 times smaller than the required 4 g dose and is clinically insignificant for seizure control in eclampsia.
Option D: Similar to 4 mcg, a 10 mcg dose is minuscule and would have no clinical effect. It underscores the critical difference between grams (g), milligrams (mg), and micrograms (mcg) in medication administration.

Clinical Relevance

Nursing practice connection: Knowing Pharmacological management of eclampsia with magnesium sulfate helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Administering MgSO₄ is a high-alert nursing activity due to its narrow therapeutic window. Nurses must perform and document checks for respiratory rate, deep tendon reflexes (patellar reflex), and hourly urine output before and during therapy to prevent toxicity.
The antidote, 10% Calcium Gluconate (10 mL IV over 3-10 minutes), must be immediately available at the patient's bedside whenever MgSO₄ is being infused.
What if? If a patient receiving MgSO₄ becomes unresponsive with a respiratory rate of 8 breaths/min and absent patellar reflexes, the nurse's first action is to stop the infusion immediately, call for help, and prepare to administer calcium gluconate.

How to Approach the Question

Identify the core question: It asks for the loading dose of a specific drug (MgSO4) for a specific condition (Eclampsia).
Recognize that this is a factual recall question common in pharmacology.
Pay strict attention to the units of measurement: grams (g), milligrams (mg), and micrograms (mcg).
Recall that eclampsia is a life-threatening emergency requiring a substantial dose of an anticonvulsant. Doses in mcg or small mg amounts are highly unlikely to be correct for a loading dose in this context.
Eliminate the options with incorrect units (mcg, mg) as they represent significant underdosing.
Select the option that reflects the standard, evidence-based gram-level dose for this condition.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 31-51

E6 Midwifery Obstetrics and Gynecology Nursing Sandeep Kaur p. 36-44