This video is provided as supplementary
material for courses taught at Howard Community
College and in this video I want to do a couple of basic examples
of drug calculations that involve unit conversion.
So here’s the first problem. The order is for
7200 milligrams. The tablets contain 6 grams.
How many tablets should be given? So I’m going to set up my equation.
The first thing I’ll do is write the amount ordered,
that’s 7200 milligrams. Tt the right side of the equation I want a space for my answer and
the unit I’m going to have, which is the number of tablets.
Each tablet contains 6 grams. So I’m gonna take that
7200 milligrams and multiply it by the fraction
1 tablet over 6 grams. Notice that I’ve got milligrams and grams,
so I’ll have to do some unit conversion. I’ll make another faction that’s going to be 1 gram over 1000 milligrams, since 1 gram is equal to 1000 milligrams.
And, this is unnecessary, but I like to turn
everything into a fraction. I’ll take that first number —
7200 milligrams — and put it over 1, and before I
multiply what I want to do is cancel out whatever units I can.
I can cancel out the milligrams. I’ve got milligrams in the
numerator and the denominator. And I can cancel out grams. I’ve got grams in the numerator and denominator. The only unit I’m left with is
tablets, and that’s good because I want to end up with tablets. Now I’ll see if I can simplify
any of this. Well, I’ve got 1000 in the denominator and 7200 in the numerator,
so I’m gonna divide both those numbers by 100 — it just
means crossing two zeros off of the end of each number. If I wanted to I
could simplify this even more. I could divide 72 by 6
and I could divide the 6 by 6, but you know at a certain point it doesn’t
matter if you simplify completely because you’ll probably end up using a
calculator and getting it out down to a decimal. So let’s just leave it at this and see what
happens. I have 72 times one tab.
So that’s 72 — I’ve already got the tablets written in.
And the denominator I’m going to end up with will be
6 times 10. So that’s 60.
72 over 60 tablets.
If I put that into a calculator what I’m going to find is it that
it equals 1.2 tablets. Now since the decimal part,
.2 is less than .5 — that’s the cut off point
for whether I’m rounding up or down — I’m just going to round this down
and I’ll end up with one tablet as dosage. So just to review this before he
go on to the second one, I set this up like a basic problem. I
started out with the ordered amount, multiplied that by the fraction 1 tab over
6 grams — because a tablet contain 6 grams — and then since I had different units,
milligrams and grams, I wrote another fraction which would
allow me to convert between grams and milligrams. I cancelled out all the units
that I could. I simplified as much as I felt like. I multiplied across and then took the fraction
I had left and using a calculator I
found that that equaled 1.2 tablets. I rounded that down and ended up with 1 tablet.
Here’s one involving micrograms. The order reads 500
micrograms. The scored tablets contain 1.2 milligrams. How many tablets should be given?
So I’ll set this up just like the last one. The amount ordered is 500 micrograms. I’ll put that over 1. I’ll multiply that by the fraction one tablet over 1.2 milligrams. Since I’m dealing with two different
units — micrograms and milligrams, I’ll have to
have a conversion fraction. So I’ll have one milligram over 1000 micrograms. And my answer is going to be some number of tablets. I want to see if I can cancel out all
units except the tablets. I can cancel out micrograms over here
in the numerator and the denominator.
I can cancel out milligrams. I’m left with just tablets and that’s
what I want to end up with. I can simplify the 500 and 1000.
I’ll just divide those by 100, and I’m going to multiply across.
I have 5, 5 tablets, but I’ve got ‘tablets’
written in, over 1.2 times 10.
That would just be 12. So I’ll take that fraction
and put it into a calculator And I find out what that equals is .41666 it seems to go on tablets. Now it said these were scored
tablets. So let’s remember the rules for scored tablets. If it’s between zero and 0.24 — if the decimal part is between 0 and 0.24,
we round down. If it’s between 0.25 and .74, then we give a half a
pill. if it’s from 0.74 up 0.9 then we give a whole pill.
Well the number we have is 0.41666. That’s between 0.25 and 0.74,
so that means we’re going to give 1/2 pill, 1/2 tablet. And that’s about it. Take care, I’ll see you next time.