Memorizing Cyp450 Inducers & Inhibitors

One of my favorite new apps on my Android phone is made by Pendragon Entertainment: USMLE Pharmacology.  Definitely recommend it – while I was setting it up yesterday, it asked me about cytochrome p450 inhibitors and inducers so many times that I accidentally learned them.

(I know, right?  Technology!)

It seems like the first step was being able to recognize that a drug is a cytochrome p450 something.  The commonly tested ones, at least on that app, were these:  Erythromycin, quinidine, rifampin, isoniazid, griseofulvin, cimetidine, carbamazepine, phenytoin, and phenobarbital.

And that’s basically the hard part, because I realized the names themselves are simply divided into “quick” names (inducers) and “slow” names (inhibitors).

Of course, you don’t need pictures to recognize that QUICKidine, GRIZZLYofulvin, CARbamazepine, RifAMPin, and PHENPHEN (Phenytoin & Phenobarbital) are “fast” names.

No, I don’t know where the grizzly bear got the illegal drugs. I suspect his dealer was in the car, and the mosquito’s all “Dude, Phenphen isn’t legal. LET ME TAKE CARE OF THAT FOR YOU.”

Similarly, no one should need a poorly-drawn picture to recognize that ICEoniazid, ERRORythromicin, and CEMENTidine are “slow” names.

Why is there a block of cement in the middle of the ice rink? I don’t know. Maybe someone just hates that poor robot.

But then, where would be the fun in that?

Ig Nobel Prize Winners in Medicine

I love everything about the Ig Nobel Prize Awards.  Their motto is “Achievements that make people laugh, then think” – which is sort of the best thing ever, right?

So I’m going to give a run-down of all the past winners, broken up into completely arbitrary categories of my own sleep-deprived choosing.
 

I Would’ve Loved to be at That IRB Meeting

2006:  “Termination of Intractable Hiccups by Digital Rectal Massage” (A strangely popular concept.)

2005:  The invention of Neuticles: Fake Testicles for Neutered Dogs.

2002:  “Scrotal Asymmetry in Man and in Ancient Sculpture”

2001: “Injuries Due To Falling Coconuts” (Published in The Journal of Trauma!  Which is apparently a thing!)

1999:  “Collecting, cataloging, and contemplating” the different types of containers patients use for urine samples.  (Out of 164 samples, the best is definitely the roll-on deodorant.)

1995: “The Effects of Unilateral Forced Nostril Breathing on Cognition”
 

I Would Totally Read That Study

2007:  The side-effects of swallowing swords. (For example, the gag reflex is a problem.)

2004:  The Effect of Country Music on Suicide.  (Money quote:  “The greater the airtime devoted to country music, the greater the white suicide rate.”)

2000: “Magnetic Resonance Imaging of Male and Female Genitals During Coitus and Female Sexual Arousal.”  (What?  And you wouldn’t?  C’mon, it’s an MRI.)
 

Useful Info with Funny Titles

2010: Symptoms of asthma can be alleviated by riding on rollercoasters.

2008:  Expensive placebos work better than inexpensive placebos

2003:  The hippocampi of London taxi drivers are more highly developed.  (I have been to London, and I am not surprised by this.)

1998:  The Man who Pricked His Finger and Smelt Putrid for Five Years.

1997:  Listening to Muzak stimulates your immune system

1993:  “Acute Management of the Zipper-Entrapped Penis”

 

That’s Dedication

2009:  Donald Unger, an allergist/immunologist, won the Medicine prize for personally investigating the claim that knuckle-cracking causes arthritis by cracking the knuckles of only one hand, daily, for six decades.
 
And finally:

Nice Try

1996: Presented to tobacco company scientists for “their unshakeable discovery, as revealed in sworn testimony to the U.S. Congress, that nicotine is not addictive.”
 

Prescription: Take with grain of salt

Directions for my dicloxacillin Rx:  “Take one tablet by mouth every 6 hours 1 hour before a meal or 2 hours after a meal for 14 days.”

According to my time-consuming math, this means I’m supposed to have only two meals a day (unless I schedule “dinner” for 4am) and each time I only have a 3 hour window to eat.

Also, I have to get up after only 6 hours of sleep to take a pill, but then can’t eat breakfast for an hour.

… For 2 weeks.

You cannot tell me people do this successfully.

No wonder patients have trouble taking prescriptions as directed.  Especially if they’re prescribed more than one with this particular “we-must-provide-100%-ideal-pharmacokinetics-or-so-help-us-god” militant brand of directions.

I may have a passing grade in pharmacology, but these pills are smarter than me.  So I’m sure I’ll eventually ignore the finer details of the directions – which is sad, since I’m a person with tons of free time, supposed higher education, and alleged common sense.

You know, for all the buzz about the alleged ‘convenience’ of prescribing a penicillinase-resistant penicillin in oral form (and I hope you correctly assume that by “all the buzz” I mean “that one comic in Clinical Micro Made Ridiculously Simple”), I’d rather just cart around an IV.

Typical Sunday night, really.

Boyfriend is currently studying for Step 2, while I’m studying for “oh god, I’m going to be an M3 in 6 months”.  So sometimes we quiz each other.

Boyfriend:  Okay. There’s a woman in her 60s – a smoker with a history of COPD and diabetes mellitus who presents to you in the middle of a current stroke.  She frequently travels on long, crowded bus rides.  What’s the most likely etiology of the stroke?
Me:  … Hmm.  Any medications?
Boyfriend:  Estrogen pills, albuterol, and metformin.
Me:  *am stumped* Well, what are her stroke symptoms?
Boyfriend:  Doesn’t matter.

Me:  Well, why does she travel on buses so much?
Boyfriend:  Uh, she’s volunteering at a nursing home in another city, 4 hours away.
Me:  What kind of buses are they?
Boyfriend: … they are buses.
Me:  Who else rides these buses?  Any homeless people?
Boyfriend:  … No.  They’re, uh, extremely fancy buses for rich people.
Me:  Does she have cats?
Boyfriend:  No.  She has never touched a cat in her life.  Or a litter box.
Me:  … What about sushi?
Boyfriend:  No.  She’s never even seen a fish.  Or eaten raw meat of any kind.  Or touched a rabbit, or a pigeon, or traveled outside of the country –

Me:  Ah, but what about-
Boyfriend:  Or Florida.  Nowhere sub-tropical.
Me:  Damn.  Well, what were the lung and heart exams like?
Boyfriend:  Lungs were surprisingly clear, though there was a mild diastolic murmur in the heart.
Me: AHA.  Can I get a chest x-ray?  And a brain CT without contrast?
Boyfriend:  CT comes back normal.  CXR shows clear lungs, slightly hyperinflated, and some mild cardiomegaly.
Me:  Aha!  Cardiac… stuff.  So.
Boyfriend:  So.
Me:  So… any claudication?
Boyfriend:  You don’t know.  She can’t tell you.  She’s currently stroking out.

Me:  See, it does matter what her stroke symptoms are!  I didn’t know she couldn’t talk.
Boyfriend:  Okay, fine – we’ll say she had a PCA stroke.  So she only has ocular deficits and can still talk to you.  And her thighs are red and swollen, which she’s unhappy about.
Me:  INFECTION.  I demand a CBC.
Boyfriend:  It’s normal.
Me:  Damn.  Thyroid?  Crepitus?
Boyfriend:  Healthy.  And no crepitus.  I promise she doesn’t have necrotizing fasciitis.
Me:  Well then, what the –
Boyfriend:  Soooo.. the thigh symptoms are..?
Me:  Oh.  OH! So she had a DVT!  A DVT that embolized to her brain!  But why did she have a clot to throw in the first place?
Boyfriend: …
Me: – you know, I still think that TB might have something to do with it.  I don’t know how, but the buses were “crowded”…
Boyfriend: … But how can a DVT embolize to the brain?
Me:  Because she has a patent foramen ovale, just like 25% of the population.
Boyfriend:  HIGH FIVE!  See, you know your stuff!

Me:  Oh. Wait, that was – that was it?  That’s the answer? But… why did she throw a clot?
Boyfriend:  … because smoking, estrogen, and long travel are all risk factors for DVT.
Me:   Damnit! I thought it had something to do with the bus exhaust fumes.
Boyfriend:  Yeah, it didn’t.

Me:  But the good news is, in two years, I’m gonna rock Step 2.
Boyfriend:  … Just so you know, on Step 2 you only get 72 seconds per question.

Things You Don’t Learn in Psych: Trypophobia

So this morning I was reading a Fashions of Star Trek tumblr (What? Come on, that’s clearly awesome) and saw a picture captioned “Sorry about the lamp, trypophobia sufferers.”

And I was like, “Huh?  What’s trypophobia?  What’s wrong with the la- OH.”

LOOK UPON ME AND DESPAIR.

And I realized that whatever that word meant, it might explain why I was vaguely creeped out.  I’ve always had an intense aversion to certain textures – maybe this “trypophobia” thing was the explanation.

So I googled it and it turned out to mean “fear of holes”.  But despite the fancy Latin, it isn’t officially a thing: the term actually originated on Urban Dictionary and isn’t recognized by any other dictionary or book.

But despite the internet recognition, a grassroots campaign to get the disorder officially recognized, and a 4,000-member facebook support group, all attempts at a Trypophobia wikipedia page have been deleted for being a “likely hoax“.  (Really, Wikipedia?  And then you turn right around and list “Monkeyphobia, as named by Lord Monkey Fist on Kim Possible“?  You should be ashamed.  Look at your life, look at your choices!)

And I get that there haven’t been any studies published yet.  But at least 4,000 people believe they have this oddly specific phobia, and many have legitimately intense variations of phobic reactions.  Isn’t that worth looking into? Heck, I don’t even care about the official ‘phobia’ label as much – I just feel strongly that Trypophobia exists as a phenomenon and is super interesting. I’m sad there’s no research.

Here’s a test.

The creators use scratching as their metric.  I didn’t feel itchy, but I was still pretty uncomfortable, so… hmmm.  (Caution: The pictures get more and more intense, so just stop as soon as you feel uneasy.  Trust me on this.  And if you’re not down with gross medical pictures, stop at 1:52.)

What do you think?

Problematic

My boyfriend’s in the home-stretch of studying for Step 2.  So after dinner – just to keep the romance alive – I usually grab a couple beers and make him quiz me.  Bonding!

Boyfriend:  Okay.  Tell me the first thing you should do for this patient:  Young male with blunt force trauma to the chest and abdomen.  Hypotensive, pale, diaphoretic, JVD.  On cardiac auscultation you hear distant heart sounds and h-
Me:  PERICARDIOCENTESIS.  Bam.
Boyfriend:  Whoa, nice!  Exactly!  Though if I had that patient, I’d probably have to get an echo first.
Me: … Oh, wait – erm.  This is real life?  …Not a multiple choice question?  … Cause I… would probably run for help.

Seriously, since you hear all heart sounds through layers of bone, muscle, and fat, how does anyone recognize a “distant” one?  Without insulting/accidentally-mortally-wounding a patient with a few extra layers of adipose tissue?

(“You have distant heart sounds.  Here, let me stick a large bore needle in your chest!” = most deathly literal interpretation of “adding insult to injury” ever.)

So while I can confidently answer the call-and-response of“Distant heart sounds” = “cardiac tamponade” on tests – I wouldn’t recognize a distant heart sound if it bit me.

(… What is “distant”? …What is a “heart”?  And why is it biting me?)

Grapefruits: Pharmacologically Evil

I’ve always tried to avoid paying attention to popular health articles that say things like: “Potatoes may decrease osteoporosis risk!” or “Potatoes may increase cataracts risk!” or “All leafy green things cure cancer except for mustard greens, which are acidic, and we all know that acid is terrible for you.” I mean, for every article like this (which, if you’re lucky enough to find a citation on what study they’re talking about, probably didn’t even come close to the headline’s conclusion), there’s another article that says the exact opposite. The obnoxiousness of the contradictions are popular reasons for people to view the whole subject of “good/bad vegetables” with suspicion.

So I was pretty surprised to find that half of our Pharmacology lecture this morning was dedicated to proving me wrong.

Drugs in our bodies are metabolized by cytochrome p450 enzymes, and these enzymes can be induced or inhibited by various other things you consume – whether they’re other drugs, air pollution, or foods you eat.  If you “induce” the right variant of the p450 enzyme (whichever one is responsible for a medication you take), you can decrease the concentration of that medication in your blood.  If you inhibit it, you can increase the concentration (and the risk of overdose).*

Interesting.  Apparently, cigarette smoke is a huge inducer of one of these enzymes, which struck me as strange (since it should be a good thing to clear cigarette smoke and car exhaust more rapidly from your body), but, since the world is out to get us, it turns out that the metabolites of cigarette smoke are more dangerous than the smoke itself.

So, fine.  “Cigarette smoking = bad” means the world makes sense again.  But what kills me about that is – you know what else induces that enzyme, presumably causing the same effects?  Broccoli and brussel sprouts. Nature has a sick sense of humor.

And an inhibitor of a p450 enzyme, strangely enough, is grapefruit juice.  This might be old news to you guys reading this, but I was shocked.**  It goes beyond the whole “well, grapefruit juice is an acid and changes the pH of the environment the drug is absorbed in” thing, which always made sense to me – it actually induces the darned enzyme and interferes with drug absorption like crazy by increasing the amount of the drug present in the blood.

I realize that none of this matters if you’re not on a relevant medication, and furthermore, that drug companies are required to tell you in the package inserts to not drink grapefruit juice.

… This is gonna sound dumb, but I just didn’t realize they meant it.

* This is all assuming that the drug isn’t a pro-drug, in which case things would be switched around, but still bad.

** One lecture is not exactly an adequate fund of knowledge to be acting like I know what I’m talking about.  Since this summarizes as “read your drug inserts and listen to your doctor”, I figure there’s no harm if I missed something – but let me know if that’s the case and I’ll edit this post.

Seriously?

Today we learned that the older a patient is, the more adipose cells you can find in a section of their bone marrow.  You can approximate a patient’s age in this way – if the bone marrow is about 50% adipocytes, the patient should be about 50 years old.

One guess as to whether this led my female friends to:

a)  Remark that that’s an interesting bit of trivia, OR
b)  Freak out about how their bone marrow will get fat.

… Yep.  That happened.

Medicine: Battlestar Galactica Edition

Boyfriend’s studying for his medical boards, and he just called me up to tell me that he’d made up the greatest mnemonic ever.

The CAG is hunting 4 cylons.

Hunting = Huntington’s Disease, CAG = a CAG trinucleotide repeat, 4 = chromosome 4.

Because Huntington’s Disease is caused by having multiple CAG repeats on the 4th chromosome.

Now whenever someone brings up Huntington’s, you can nod your head and act all sage and say, “Yeah, isn’t it scary just how much damage a CAG repeat can do? It’s on the 4th chromosome for Huntington’s, isn’t it?” and they will think you’re a complete nerd GENIUS.

Diagnosis: Glee

Watching Glee with my boyfriend – a med student –  is awesome.  The boyfriend hadn’t seen it yet, so I thought I was pointing out some awesome trivia (it was my 2nd time watching it)

Me: Fun fact: The paralyzed character there? He’s actually played by a guy who’s paralyzed in real life.
Boyfriend : Yeah, I figured he was either coached really well or was paralyzed, leaning towards paralyzed.
Me : … Wait, how?
Boyfriend : See him breathing there, in between lines? His diaphragm is moving, but his chest isn’t expanding at all.
Me : Hey, yeah, that’s true.
Boyfriend : And the diaphragm is innervated by C3, C4, and C5, while the intercostal muscles in the ribcage are innervated bythoracic spinal nerves.

So if you become paralyzed from the neck down, you’ll still have some combination of C3/4/5 (or else you wouldn’t be alive) – so your diaphragm can let you breathe, but you won’t have anything further down, so you won’t have the thoracic spinal nerves and therefore no intercostal muscles in your rib cage to expand/contract your ribs and therefore your lungs. Therefore, someone with cervical paralysis will move their diaphragm but not their ribcage. An actor who doesn’t know this would probably just continue to breathe the way almost all of us (the exception: very trained singers) do – chest expansion.

It’s crazy. I mean, I know the innervations, too, but I guess you need to actually have an eye towards diagnosing patients to figure out that a guy on TV is most likely actually paralyzed and not just acting.

I wanna be a smart med student someday.