I guess a good place to start is the basics.
The formulae for calculating medication doses are obviously a little different from each other depending on what type of medication is to be given (oral or parenteral) or if it’s an IV infusion requiring rate calculation. For this post, I’ll just cover the basic formula for tablets. It works the same way for other oral medications too, such as liquids.
The basics: a/b x c = d
It’s often presented like this: dose ordered/stock on hand x volume = dose to administer
But what dose that mean? If it’s a tablet, it goes like this (for example):
Doctor has ordered 50mg of Medication X, so that goes in ‘a’ or ‘dose ordered’.
Stock on hand is 25mg tablets of Medication X, so that goes in ‘b’ or ‘stock on hand’.
Volume in this instance is ‘tablets’ in ‘c’.
Now it looks like this: 50mg/25mg x tablets = dose to administer
so we divide the 25 into 50, getting 2, so 2 x tablets = 2 tablets
If the dose ordered had been 62.5mg, it would look like this: 62.5/25 x tab = dose, therefore 2.5 tablets.
Practicing the maths can be tricky sometimes, but the basic formula stays the same. Once you master the formula and understand the concept, it’s just the maths.
Dose Coach is available on iTunes! After an initial version was uploaded, we are now launching the app for wider distribution and we hope you’ll give it a try!
Search for Dose Coach on the iTunes app store or follow the link on this page.
It provides hundreds of oral, parenteral and drip problems and provides you immediate feedback and advice as you answer. It is designed to help you practice for that all important Drug Calc exam so that you can go in confident that you can manage the math in your head.
Dose Coach is designed knowing that you don’t go into nursing for your love of mathematics, and that practice makes perfect.
I enjoy tackling a good problem. When Sarah started her graduate entry registered nursing course @Flinders University she told me about the significant numbers of her fellow students who were concerned about and having trouble with drug calculation exams. These routine calculations need to be done correctly to ensure patients get the correct dosages of prescribed medication.
Reasonably, universities expect students to be able to pass the exams with 100 percent correct responses. Unfortunately, the math education routinely lets students down and leaves them with low confidence in their ability to pass. Research (Hodge, 2002) suggests that computers can effectively assist the third of nursing students who struggle to learn dose calculations and improve performance on exams.
What better platform for this type of practice than mobiles?
So with Sarah in school full time, I decided to take some time off my day job to put together Dose Coach, a dose calculation practice app designed to improve confidence with realistic practice problems and easy to understand advice.
This app is not designed to do the calculations, but rather to help students gain confidence in the mental arithmetic required to administer oral, parenteral and intravenous drip problems.