A pharmacy technician receives a prescription for 15mg of Augmentin in 30ml of cherry syrup. To measure such a small amount, the technician must use the aliquot method. This involves calculating the least weighable quantity, weighing out a factor of the prescribed amount, weighing the appropriate amount of diluent, mixing the drug and diluent, and determining the portion of the mixture that contains the prescribed dose. Following the aliquot method steps, the technician determines they need to weigh 120mg of Augmentin and 960mg of diluent, and the prescribed 15mg dose is contained in 120mg of the mixture.

2. A pharmacy
technician
receives a
prescription.

3. It is for
15mg of
Augmentin
in 30ml
cherry
syrup.

4. In order to
weigh
something
that small
we have to
use the
aliquot
method.

5. First we have to know the steps for
Aliquot measuring
Steps for Weight Aliquot Measuring
1. Calculate least weighable quantity based on
balance sensitivity and permissible margin of
error.
2. Determine the amount of the ordered drug
that you will actually weigh out.
3. Determine the amount of diluent.
4. Combine the drug and diluent measured in
steps 2 & 3 and mix them well.
5. Determine the amount of mixture needed to
provide the originally ordered amount.

6. Step 1
A class A balance has a
sensitivity of 6mg with a 5%
margin of error. To figure out
the least weighable quantity
(LWQ) the equation is:
100 x sensitivity = LWQ
% margin of error

7. Least Weighable Quantity
100 x 6 mg = ? mg
5
What is the least amount of drug we
can weigh?
240
120

9. Congratulations!
Good Job! So the least amount of Augmentin we
can weigh is 120 mg.
How are we going to
weigh 15mg?
Lets go to Step 2

10. Step 2
Determine the
amount of the
ordered drug
that you will
actually weigh
out. This
amount must be
equal to or
greater than the
LWQ.

11. To calculate the amount of drug to
weigh out, multiply the amount of
drug ordered by a whole number until
you have an amount equal to or
greater than the LWQ. This number is
called a factor and it can be any
number you want. Just remember we
want to keep it as close to the LWQ as
possible.

12. Multiply the
amount by a
number to get it
close to 120 mg.

13. What factor can you multiply 15 mg to
give you a number close to or equal to
120 mg?
15 mg x ? = ?
10
8

15. Congratulations!
So when we multiply our 15 mg by
a factor of 8 we get 120 mg. Which
is exactly our LWQ. This is
important because it will cut down
on waste later on.
Now lets figure out how much
diluent we need.

16. Step 3
To determine
the amount of
diluent we
multiply the
LWQ by our
factor.

17. LWQ = 120 mg
Factor = 8
120 mg x 8 = ?
720
960

19. Congratulations!
120 mg x 8 = 960 mg
So we are going to weigh 960 mg of
diluent and 120 mg of Augmentin.
Lets go to the next step!

20. Step 4
Combine the
drug and
diluent
measured in
steps 2 & 3 and
mix them well.

21. Step 5
Determine the
amount of
mixture needed
to provide the
originally
ordered amount.

22. We will use the following equation to
figure out what part of the mixture will
contain our 15 mg of Augmentin.
x mg mixture=amount of drug ordered x total mixture
amount of drug weighed

23. X = 15mg (amt of drug ordered) x 960mg (total mixture)
120mg (amt of drug weighed)
X=?
240
120

25. Congratulations!
From the 960 mg pile of mixture we will
weigh out 120 mg.
In that 120 mg will be the originally ordered
15mg of Augmentin. We can then mix it
with the cherry syrup and the compound
will be finished. The 840 mg of mixture left
over may be discarded.

26. Now all
that’s left
is to label
it and
dispense it
to the
waiting
patient.