Wednesday, October 20, 2010

All Tied Up Over Tylenol

Overdosage with Tylenol is the most common cause of acute liver failure, and attempts have recently been made to educate the public that Tylenol (or acetaminophen, or APAP) is not an innocuous drug. People may not be aware that acetaminophen is present in many products other than "Tylenol" leading to doubling-up and inadvertent overdose, and there can be confusion over strengths of different products -- regular strength tabs, extra-strength tabs, chewable tabs, infant drops which are 100mg/ 1ml, and children's liquid which is 160mg per 5ml. For adults, 4000mg per day is the maximum dosage, or 8 tablets of 'extra strength' Tylenol equivalent, and there is talk of lowering that recommendation.

Anyway, the thing that worries me most is the kids, because of the aforementioned strength differences and the lack of faith I have in many of the caregivers who give the doses. You remember when they pulled all those OTC pediatric cough/cold products off the market not long ago? It wasn't because the medications were inherently unsafe, it was because there were too damn many dosage errors to justify leaving them out there. Every time I sold one of those things I attempted to make sure the parent knew how much to give, but they rarely initiated the question themselves.

Getting back to Tylenol, we get a lot of prescriptions for it because it is covered by state assistance for those who are eligible. Pediatric dose, as we all know: 10 to 15 mg per kg every 4-6 hours, maximum 5 doses daily. But after checking the child's weight, we consistently get doses that are written too high. Usually they creep up into the 16-17-18 mg/kg range, sometimes more. Okay, maybe a couple of doses isn't a big deal, but legally as far as that labeling is concerned it's OK for that child to get that dose every 4 hours for the next... well, indefinitely. I'm often nervous about assuming that a non-English speaking parent even remembers what 1.2 mL looks like on that dropper. We always have this conundrum --- should we call and bug the doctors/nurse about it EVERY time and hold up the prescription till they call back? Should we go ahead and change it to a more correct dosage and initiate a phone call or fax back to the office and hope it gets changed in their medical record? Or do we decide we've called them enough times and just tell the parent the correct dose and make sure they know how to give it? Is it worth all the time spent? It happens virtually every day. Are we just getting too wound up about the whole thing?

I'm curious as to how other folks handle prescriptions for OTC items like this.

For the record, I never use those dosing charts that give a weight 'range' and assign a dose for it. I calculate 12mg/kg (right smack in the middle) and then round up or down to the next logical dosage unit (1/2 - 1 - 1 & 1/2 teaspoon, dropperful, etc.) Done.


The Beach Life said...

I caught a prescription yesterday where a pain management doc was writing 7800mg of APAP a day for a patient. If someone needs up to 12 Darvocet a day, I think it may be time to graduate to something stronger.

Anonymous said...

What irks me is all the doctors who tell parents to get the APAP infants drops after their shots & don't give them the dose! Most of the time I have parents of 6 month olds coming to my counter wanting to know where the Tylenol is (uh-it's been recalled for over a year~long enough lose its spot on the shelf!) & they have no clue how to dose it! So for shots I do the 10mg/kg & round to the closest even dose- but I also calculate 15 mg/kg for the range and tell them to start with the lowest dose-for shots they prob don't need the high one and I can't always trust the parents!

Anonymous said...

I'll leave this bravo to Ol' Poth, but our non-English speaking patients often know more about milliliters than our English-speakers. (I tend to try to stay away from teaspoons and other traditional irrationalities.)

As for the high doses for the wee ones, when they come through the ER, the docs seem to have no qualm about giving a high dose in the ER at 1 AM, but then compound the issue by giving a script with the same 'error' in prescribing. Maybe, since the child will inevitably weigh more in a short while they think the higher dose is advice for next time. Then, there's that doc that documents the dose given as 10 mg/Kg and no indication of the child's weight!

Anyway, we're keeping track of dosing trends/errors to present to the ER group since at this juncture in emergency primary care the MD function is also as only the point-of-care, and they'd do well to get it right the first time they intervene in a child's care in a worried family situation.

Anonymous said...

I refer to Dr sears website on acetaminophen dosing. When patients ask me for a dose for a child under the age of two, SAy its not labeld to be given that way, but if you want furhter info use the Dr sears website for apap dosing. or call the pedi .... here the link

Anonymous said...

Pediatric livers are quite resilient to the effects of Tylenol, the liver has plenty of NAPQI. I have heard from a few Graybeards in Emergency Medicine that there are no known accidental overdoses of tylenol resulting in liver failure in children. I did not do a lit search to confirm, but the sources are respected.