MCQ Pharmacology Answer 7

The correct answer is E
Explanation

Beta-1 selective blockers

These include atenolol and metoprolol (as well as betaxolol, bevantolol, and perhaps esmolol).

Metoprolol
This beta blocker lacks ISA and MSA; one can deduce its metabolism and short half-life from its lipophilicity. Some slow-release formulations of metoprolol have peculiar doses.

Atenolol

Examination candidates should probably know this agent fairly well. Important topics to discuss would be its water solubility, metabolism, ß-1 selectivity, and recent studies showing improved post-operative survival even after very short-term use in the peri-operative period.

Esmolol
This beta blocker is relatively beta-1 selective. hydrolysis by nonspecific esterases accounts for its tiny half-life of about 9 minutes. The traditional approach of starting therapy with a 0.5mg/kg IV bolus is excessive,and potentially life-threatening. Be more gentle. This agent has been much abused to "manage tachycardia" intra-operatively, where the anaesthetist should rather be thinking about the cause of the tachycardia, for example, pain)!

Non-selective beta blockers
There's a confusing array of these agents, including propranolol, nadolol, pindolol, sotalol, oxprenolol and timolol. From a practical (and examination) point of view, it's probably important to know the following well:
propranolol

(Note its lipophilicity and consequent hepatic metabolism, lack of ISA, irrelevant MSA, short half-life, and several exotic effects including inhibition of peripheral conversion of thyroxine to T3, as well as shift of the Hb:O2 dissociation curve to the right)! carvedilol;

Category: Pharmacology MCQs