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Question 484
Pharmacology → General
Classification
Question
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A sulphonylurea is being considered in a woman who may become pregnant. Which combination of properties is most characteristic of this drug class?
Question Stem
Select the single best answer.
Options
A
They do not cross the placenta and hyperglycaemia is their most common adverse effect
B
They cross the placenta and may stimulate fetal beta cells; hypoglycaemia is their most common adverse effect
C
They require complete absence of endogenous insulin and commonly cause hyperuricaemia
D
They improve insulin sensitivity without placental transfer and do not cause hypoglycaemia
E
They inhibit renal prostaglandin synthesis and may prematurely close the ductus arteriosus
Explanation
Sulphonylureas cross the placenta and may cause fetal beta-cell stimulation. Hypoglycaemia is their most common adverse effect and can occasionally be severe. Tolbutamide has the lowest risk because of its low potency and short duration of action.
Option Validity
A) Sulphonylureas cross the placenta, and hypoglycaemia rather than hyperglycaemia is their most common adverse effect.
C) Requirement for residual endogenous insulin is a property described for biguanide action; hyperuricaemia is associated with diuretic therapy.
D) Improvement of insulin sensitivity without causing hypoglycaemia characterises metformin rather than sulphonylureas.
E) Inhibition of renal prostaglandin synthesis and the risk of premature ductal closure are associated with NSAIDs.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 12: Pharmacology. Drugs Interfering with Glucose Metabolism, p.347.