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Discussion

What is this Dosage problem asking?

Ok here is the question:

The order reads Asa gr X po now. You have Asa 325 mg per tablet. How many tablets should you give?

Well I took the question to mean that the order of the Asa (in grains) is to be given by mouth but what does X mean? I looked to a few medical terminology websites but I still don't know what X means and what the question is asking.

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In the Roman numeral system, X=10. I assume that's what it's saying.

Actually, it has to do with the old dosing system called "Apothecary," used for medicine.

ASA gr. X (the Roman numberal for 10) means "Aspirin, 10 grains," which equals approximately 650 mg.

Here's a link to a conversion table to help you:

http://www.tostepharmd.net/pharm/clinical/measurement.html

And here's an actual book excerpt that explains the whole thing:

http://books.google.com/books?id=cSnugQ4sPdIC&pg=PA63&lpg=PA63&dq=apothecary+system+grain+x&source=web&ots=JRm6nwNbRl&sig=nJahJ0pC3JMXr1L8j6s-BMXQ-8A#PPA64,M1

  • Experts

The problem is asking this:

Give Aspirin 10 grains orally now. You have Aspirin 325mg tablets on hand. How many tablets should you give?

To do this problem, you need to know the conversion factor of grains to mg's. This is also a common order that was written frequently before the days of Tylenol, so it is grounded in actual practice.

  • Author

Thanks Everyone!

So this is how I set up the problem:

10gr x 60mg/1gr=600mg

Since there is 325 mg per tablet I divid 600mg/325 mg to get the total number of tablets. I got 1.8

On one of my conversion sheets it says that 1 gr=60 mg and on another it has the exact conversion 1gr=64.8 mg. What one should I use? What one should I memorize?

  • Experts

You set up the solution to the problem correctly. The conversion factor you should use is:

1 grain = 65 mg

You get this by rounding off the 64.8 mg to 65 mg. We used to just remember that 5 grains was equal to 324 mg which is close enough to 325 mg. Each 325 mg tablet of Aspirin is the same as 5 grains of Aspirin. So, you would give 2 tablets to give the 10 grain dose. Or, you just round the 1.8 tablets up to 2 tablets since there is no way to cut one tablet into 0.8th of a piece.

  • Author

Thanks Daytonite!

Do you know where I can find a conversion sheet that has all the conversions I need to know and is accurate? I have two conversion sheets sitting in front of me that says that 1gr=60mg and I already made my flashcard (darn it) so I just want to start over and do this correctly.

Thanks,

Rachel

  • Experts

I haven't found one that is all-purpose. You just have to compile your own list. Like for the 10 grains. Sometimes 60mg will work for doing a problem and sometimes 65mg will work better. There are conversions listed in the appendix of my Taber's encyclopedia and my nursing drug handbook and some of them are a little different. There are always subtle differences when going between apothecary and metric system measurements. That's just the way it is. That's why the ISMP (Institute for Safe Medication Practice) as well as JCAHO (Joint Commission for the Accreditation of Healthcare Organizations) has really been pushing for doctors to stop writing orders where we have to do these kinds of calculations.

I also wanted to point out that the reason you can round that problem off to 2 tablets has to do with scientific expression of the answer. This goes back to the disciplines of chemistry and physics. When you are given mathematical figures to work with you always round off to the lowest number of places that were contained in the information given. Since that problem asked "how many tablets" and we know tablets always come in a whole number, then the answer should, theoretically, be expressed as a whole number. The only time I might deviate from that is if the answer turned out to be 1.5 tablet because, in practice, I know I can break a tablet in half if it is scored. Remember for 0.5 and above you round up; for 0.4 and below you leave the whole number as is.

1 grain = 60-65 mg.

Hi can someone help me. I have this exam this thursday so i need an answer asap. ANyhow I"m doing chap 6 for the medical dosage class and many of the answer are in whole numbers. IF you get something like 2.60 caplets do you round that off... I saw some answers to be 1 1/2 as well so I am not sure.

Is the answer suppose to be in whole number form? The question asks for Caplets.. or Tablets etc so just want to know since my prof takes off every lil point off just form something like that.

Honest - I'm sure every program is a bit different but I can tell you the rules that we go by.

First, NEVER use a trailing 0. So write 2.6 instead of 2.60. The thought is that if someone has some sloppy handwriting that can look like 260 instead of 2.6. Someone could still interpret 2.6 as 26 but you're still better off at 26 then if you gave them 260. On the flip side you always use a 0 before a decimal point. So you would write 0.5 instead of .5 for the same reasons, .5 might look like 5. Make sense?

For us rounding depends on what you're given. If you're giving a caplet or something that cannot be split, then you would round to a whole number. In your example 2.6 would round to 3. If you are giving a tablet that can be cut in half, then you would round to the nearest .5. So 1.1, 1.2 & 1.3 would round to 1, 1.3 (can go either way as it is equal distance from 1 and 1.5), 1.4, 1.5, 1.6, & 1.7 would be 1.5 tablets and 1.8 & 1.9 would be 2 tablets.

My prof did throw a screwy one in on the last test giving us a tablet that is scored in 4ths so we had to round to the nearest .25 of a tablet.

For ml we always round to the tenth (so 2.6 not 2.64).

hth

yes that was very helpful I didn't now about the rounding for the half cap and tabs. However... I just realized as I was talking to one of my classmates the word problem mentions scored tablets which refers to tablets that can be cut in half. THis is the reason why the fraction comes in that's why the answers are 1/2 or 1 1/2.. my professor told me that usually we don't use decimal for cap and tab unless its asking for the metric system like ML, Kg and so forth.

I have the exam tonight and i need to Ace that.. i only got like 3 wrong in the other exam and I got an 85 over some silly mistakes.. one of the questions she gave us was tricky too.. i hate those...

Thanks again.. I appreciate your help..

I have a dose question with an answer but I still can't figure out how the answer is what it is, so if anyone can explain it I would appreciate that:

A nurse is to give the liquid medicine 3 times a day. The morning dose is 3/4 ounce, the noon dose is 1/2 ounce and the evening dose is 3/4 ounce. The nurse has 1 ounce of medicine at noon. How much more is needed?

The answer is 1 .....I do not know why

I don't get this question, maybe I am over thinking it, has the nurse already given the noon dose when she has 1 ounce left or does she have an ounce at noon prior to the noon dose? Why is the answer 1?

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