Order the following diuretics from beginning to end of a nephron based on where they exert their pharmacologic action in the renal tubular system.
B. Ethacrynic Acid
Answer with Rationale:
The correct order is D-B-C-A.
As has been detailed in previous question of the week columns, there are 5 ways a question can be asked on the exam. Ordered response involves ranking really about anything in a certain order.
This question in particular can be a bit difficult for a number of reasons. First, you have to know the diuretic in question (by either generic or brand name). I chose the diuretics for this question specifically as they are not Lasix, HCTZ, etc. as they may not be the most well known diuretic. Third, you not only have to know the mechanism of action, you have to know where exactly this takes place because clinically this has an impact on amount of fluid loss exerted by the diuretic at the site of action as well as that diuretic's effect on electrolytes. Therefore the correct order is carbonic anhydrase inhibitor (acetazolamide), loop diuretic (ethacrynic acid), thiazide diuretic (chlorthalidone), and aldosterone antagonists (eplerenone).
Keep in mind that the order can be asked a number of different ways. This question could have asked for the reverse order and then the correct answer would be the opposite. Be sure and read carefully to ensure you order correctly!
Good luck to many of you as you prepare for the residency interview process as well as your first major job interviews.
Have a great week!