SBA — Single Best Answer · Review
Question 479
Pharmacology → General
Classification
Question
SSBAQuestion Header
Which pharmacological profile best characterises propranolol?
Question Stem
Select the single best answer.
Options
A
Selective beta-1 antagonist with intrinsic sympathomimetic activity and a small volume of distribution
B
Selective beta-2 antagonist with intrinsic sympathomimetic activity and a long elimination half-life
C
Non-selective beta antagonist with intrinsic sympathomimetic activity and poor central nervous system penetration
D
Non-selective beta-1 and beta-2 antagonist with no intrinsic sympathomimetic activity, a large volume of distribution and an elimination half-life of about 4 hours
E
Alpha-2 agonist with a large volume of distribution and an elimination half-life of about 4 hours
Explanation
Propranolol is a non-selective beta-1 and beta-2 adrenoceptor antagonist with no intrinsic sympathomimetic activity. It has a large volume of distribution and a relatively short elimination half-life of approximately 4 hours.
Option Validity
A) Propranolol is non-selective, has no intrinsic sympathomimetic activity and has a large rather than small volume of distribution.
B) Propranolol blocks both beta-1 and beta-2 receptors and has no intrinsic sympathomimetic activity.
C) Although propranolol is non-selective, it has no intrinsic sympathomimetic activity and is lipid soluble, readily crossing the blood-brain barrier.
E) Central alpha-2 agonism characterises clonidine rather than propranolol.
Further Reading
Saxena R. Textbook for MRCOG-1. Chapter 12: Pharmacology. Beta Blockers, p.345.