Answer: Question 2. Avoid the Foils

by Bob Stuntz


2.  Which of the following drugs is not amenable to dialysis in acute overdose?

A.  Amytriptyline

B.  Lithium

C.  Salicylates

D.  Theophylline

Answer: A, Amytriptyline

This is an example of a type I question, as we discussed before.  It asks a question, and you either know the answer or you don’t.  In some ways these are the easiest ones, as they usually are right there for you.  Sometimes, however, the test writers like to shake these up with “foils” in the answer choices, or answer choices that are meant to sound right but are not.  In this case, theophylline.  How is this a foil?

When I wrote this, I figured most people know that Lithium and Salicylates can be dialyzed.  For these types of questions, if you don’t know the answer off the top of your head, you usually look back to personal experience.  I personally have never seen a theophylline overdose, much less used it or seen anyone using it therapeutically.  Unless you are taking a ConCert, you have probably not seen many of them either.  When we take board review classes, and in standardized tests classically, we are often told if something seems obscure or unfamiliar, it is unlikely to be correct.  

You also get a foil in the form of Amitriptyline.  One teaching in test taking strategy is that if you see two answers that are similar, one of them is likely to be the answer.  Let’s say you did not study Tox very well, and you saw that Answers A and D both end in “-line.”  Being a good test taker, you say well, I don’t know the pharmacology very well, they both end in -line, so one of them is the answer.  I’ve never seen theophylline overdose, so why would they want me to know that it is dialyzable?  I’ve seen amitryptyline overdose, they get pretty sick, I bet they need dialysis.  (Note: not saying these two drugs are related at all, more giving the example of a frazzled test taker pulling at strings).  

These questions are largely rote memorization, and should be easy.  You either know them or you don’t.  But remember, keep a close eye out for foils that are written to confuse you.  Go back to clinical experience.  Again, most residents get Lithium and salicylates slammed into their heads as working with dialysis.  If you have seen something in real life, think about it.  Think about the bad TCA overdoses you have seen: have you ever called to get immediate dialysis?  No, you started them on bicarb and provided supportive care.  And remember, just because you have never seen something does not mean it does not exist or cannot be true.  

Here is a list with a mnemonic (if you’re into those) for drugs you dialyze in acute overdose.   For tox questions, there are certain things to definitely memorize:

1. Toxidromes (sympathomimetic, serotinergic, etc)

2. Antidotes for specific drugs

3. Management of specific drug/drug class ingestions (Tylenol, toxic alcohols, ASA, TCA)

4. Lists of treatments (what drugs work with dialysis, WBI, activated charcoal, etc).  

More to come on these in the future…