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Question 452
Pharmacology → General
Classification
Question
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A woman receives intramuscular pethidine during labour and subsequently delivers a neonate with respiratory depression. Which timing of delivery after the maternal injection is particularly associated with this complication?
Question Stem
Select the single best answer.
Options
A
Within the first 5 minutes only
B
Between 10 and 20 minutes
C
Between 20 and 40 minutes
D
Between 1 and 3 hours
E
Only after more than 12 hours
Explanation
Centrally acting opioids cross the placenta, and neonatal respiratory depression may occur when delivery takes place 1–3 hours after intramuscular pethidine. Pethidine also reaches the fetus rapidly after intravenous administration.
Option Validity
A) Neonatal respiratory depression is not restricted to the first few minutes after intramuscular administration.
B) This is not the characteristic timing interval for neonatal respiratory depression after intramuscular pethidine.
C) The relevant interval is 1–3 hours after intramuscular administration.
E) The complication is not described as requiring an interval greater than 12 hours.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 12: Pharmacology. Analgesics, pp.346–347.