I’m doing a presentation on breastfeeding and was reminded that Vitamin D is dosed in International Units rather than micrograms. I’d always assumed it was because the RDA was some really funny number, but it turns out it’s just 10mcg. How dull. What’s the advantage of using IUs over the metric quantity?
Here’s a more dramatic example: Penicillin G is dosed in millions of units. During a delivery of a Group B Strep-positive mom, we give 2.5 to 5 million units at a dose. Why would that ever be useful? Even in pediatric patients, doses aren’t a millionth, or even a ten-thousandth, of what we’d give adults.
I’m sure each drug has its separate history, but I’m curious and no pharmacist I’ve asked (3) has been able to enlighten me.
I have no idea. Alcohol in the UK is also measured in “units.” It’s not completely unheard of in the US, but tends not to be used outside of public health surveys, and it’s fairly rare there. To make matters more confusing, the British “unit” of alcohol and the American “unit” are completely different. And there is no standard measurement for alcohol in the US besides the vague “drink.” There’s a “standard drink” (which may be the same as a “unit,” I don’t recall) but it has only a loose connection with what you’re actually served in a bar.
It took me a little bit, but Google answered the Penicillin question, at least indirectly. It turns out that different penicillin salts have different masses (duh), so by expressing dosages in “units” you don’t have to specify “x mg of penicillin G sodium.”
For what it’s worth, a “unit” turns out to be 0.6mg of active penicillin.
I believe this is the answer for others, as well. Many of the minerals come in several different forms, and 50mg of one doesn’t equal 50mg of another. IU keeps us on the same page, and makes us less likely to overdose or underdose our patient should the pharmacy substitute a different form.
Related question: is there any insulin that isn’t 100units to 1mL? I haven’t seen it any other way, but we still say dosing in units. Is it just to avoid horrendous microliter =/= milliliter drug errors?
Are you sure that is 0.6 micrograms and not milligrams? Because 5 million units at 0.6 mg per unit is 3 kilograms (a quick search seems to confirm that it is indeed 0.6 micrograms per unit, or 3 grams for 5 million units). Of course, I suppose this shows why they use units, no confusing micrograms and milligrams (although most people would realize that it can’t be in milligrams, at least in this case).
I’m kind of skeptical of the whole micro vs. milligrams confusion issue. I mean, I’d hope that anybody trusted with distributing medications can tell the difference between ug and mg.
It’s a major issue, especially in scribbled writing or (in my case, careless typing). All it takes is one person to do serious harm. And it’s much more likely with less common drugs where people aren’t used to a “normal” dose.
As an aside, I only partially explained penicillin. Since it’s always given in milligram quantities, it’s a wonder a unit is so minute.
I’ve read that with vitamins in IU, at least, it’s because it’s difficult or impractical or pointless to isolate the molecules that are the vitamin, so they use IU to mean “enough of something containing the vitamin to have a certain effect.”
Oh, don’t be. There are a whole host of abbreviations we’re not supposed to use anymore, because medication errors kills thousands of people every year. And it’s not always because of the notorious “chicken scratch” handwriting of doctors. Sometimes even fairly good handwriting can lead to ambiguities.
Yes, there is U-500 insulin, where there is 500 Units of insulin in 1 mL. Though, it isn’t very popular. I’ve never actually dispensed U-500 insulin, or seen an RX for it. I’ve only actually seen it once when I was doing a rotation in a hospital pharmacy (even there is wasn’t popular).
It is for use in people with severe insulin resistance, people who would routinely have to inject greater than 100 units of insulin at a time.
Awesome. Thank you for the information! (I feel like there should be a little "“The More You Know” star here. …is that too local a reference to make any sense to anyone else? )
Honestly, I’m surprised they never mentioned U-500 insulin to you in nursing school. This is exactly the type of error that would lead to someone ending up in Diabetic ketoacidosis or in a hypoglycemic shock (depending on the direction of the error). Not that I expect you to know much about it, but just the fact that it exists…
ETA: Do I look like an NBC Public service announcement to you? Though, I admit I always liked the music that goes on after the fact… Though in practice, the musical tune I use most is the Jeopardy tune (Me: “What’s her date of birth?”, Him: “Ummm…”, Me: “[start humming Jeopardy tune]”).
One of the biggest drawbacks, IMHO, of a two year AAS nursing degree instead of a BSN is no dedicated pharmacology class. (That and no Community Nursing are the only real differences that I and my BSN holding friends have identified when we compare.) It’s catch as catch can as we discuss various diseases. It’s possible it was mentioned at some point, but if so I was a bad student and don’t recall it.
I’m taking a pharm class this summer to try to fill in the gaps.
Considering that most medical treatment in todays day and age is some sort of medication, I’m surprised they don’t have a pharmacology class… But then, I took almost 4 years of nothing but pharmacology classes, so I’m sure I’m biased…
When I council people on their medication, or their new disease states, I’ve heard more times then I can remember, “You should be a doctor”, and of course my classic response, “I am a Doctor… A Doctor of Pharmacology”… The main difference between a pharmacist and a MD or DO, we have 4 years of pharmacology and treatment, with one semester of diagnostics… while MD/DO’s have 4 years of diagnostics and treatment… with one semester of pharmacology…
In an ideal medical world, the MD/DO would diagnose the disease, the Pharmacist would select the treatment of the disease, and the nurse would administer the treatment… (IMHO of course)
I’ve watched over my doctor’s shoulder a few times, as he entered an Rx. The GUI-based software he uses has drop-down menus or list-boxes with specific meds and doses, etc., on them. So it looks like the doctor doesn’t get to hand-type his own orders, but rather, he gets to point-and-click on various menus that list the available choices. (I don’t know if there is also an option for the doctor to hand-type a non-standard order.)
I’m right there with ya. I’m that nurse who’s always telling patients, “Forget about your doctor… talk to your *pharmacist *when you have medication questions! He’s the one who knows this stuff best!” My dad was a Pharm D, you see. He worked at a children’s hospital, so did lots of consulting and staff education and compounding and developing new protocols - all that behind the scenes stuff most people don’t know you do. I’ve got *huge *heaping piles of respect for all the information you have in your noggins.
I get that “you should have been a doctor” thing, too. :dubious: No, I should be a nurse. Doctors think like doctors and nurses think like nurses. I’m an okay-now-someday-I’ll-be-good nurse. I’d make an awful doctor.
Let’s face it - doctors have the best publicists. Nurses and pharmacists are still considered servants of the doctors by most laypeople (and not a few doctors).
Senegoid, there’s always some way to override the system, in my experience. But yes, one of the way we’re trying to minimize errors is with drop down choices and clicky boxes, so you have to work really hard to enter something truly stupid! ETA And the best systems aren’t in use anywhere. I truly wish I could scan and post you the “report” I got from a doctor this week. It’s a single page of copy paper, handwritten…in red pencil. WTF? I can barely read the thing, it’s got a body weight over here, and a diagnosis over there (but no mention of all the other diagnoses) and a couple of phrases in the middle… It’s incredibly, screamingly unprofessional. But it’s the best I’ve got for the moment, and I don’t expect I’ll get anything better from his office until after the holiday.
(Sorry for the thread drift…this is exactly why I wouldn’t make a great doctor…don’t have that kind of focus; I’m all about the gestalt…)
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