Extra information:
Title: Drug Dosage Calculations
**Note: If you see a word or phrase that you do not understand, look to
this panel on the right to see if a definition or synonym has been provided.
A synonym is word that means the same as another word (for example:
‘big’ and ‘large’ are synonyms, as they both have the same meaning). If
extra information has not been provided, look up the word or phrase and
write the information down in that panel to help you remember!
Definition: Symptom: a
change in the body or
mind which indicates that
a disease is present
Explore it - I:
1) You are a nurse who is working at an urgent care facility. A mother and
her 6 year old son come in with the same symptoms. You perform an exam
and find that they both have high fevers, and you decide to address this
symptom by administering a fever-reducing drug. You have determined the
type of drug that think they need, but now you must decide how much to
give them. What sorts of factors might play a role in this decision? For each
factor, explain why it may be important to consider.
2) Read the information on the labels of the over-the-counter fever reducer
medications from your teacher.
a. Compare the different labels to find the information necessary to
complete the chart below.
Type of medication
Active Ingredient
Amount of medication
in one whole dose
Units used
Type of medication
Active Ingredient
Amount of medication
in one whole dose
Units used
Tylenol
Infant
Children’s
Adult
Motrin
Infant
Children’s
Adult
Synonym:
The word ‘administering’
in this context means
‘giving’
Synonym:
The word ‘reduce’ means
to lower or to bring
down, so a feverreducing drug will lower
or bring down a fever.
Extra information: An
over-the-counter drug
(also called an OTC drug)
is one that you can buy at
the store without going
to a doctor to get a
prescription
Definition: ingredient: a
change in the body or
mind which indicates that
a disease is present
Discuss it - I:
1) Look at the chart you created. Why do you think that the amount of
medication varies between the age group of the patient?
2) Look at the chart you created. Within one age group, compare the
different types of fever-reducing drugs. Why do you think the amount of
medication varies between the different drug types?
3) What are some of the warnings described for the different drugs that are
related to dose?
4) How might the dosing instructions and the warnings be related?
5) What do you think is meant by ‘active ingredient?’
Definition: warning
something (such as an
action or a statement) that
tells someone about
possible danger or trouble
Explore it II:
You learned in part 1 that doses will differ from person to person and from
drug to drug. For each drug, you also learned that when someone takes a
drug, the medication they need is mixed with other ingredients. So how
much of the pill actually contains medicine? One way to mathematically
represent how much of the dose of a drug is made up of the active
ingredient is by describing it as a percent.
1) What information would you need to know about one dose of medicine
to be able to calculate the percent of the dose that is made up of the active
ingredient? How would you use that data to calculate percent?
2) For each of the adult formulas of the drugs from example one, collect
the data you would need to calculate the percentage of one dose that is
made up of active ingredient. Show your work.
Discuss it - II:
1) Did the percent active ingredient differ from one type of drug to the
other? If so, why might this be?
2) Why do you think the medications contain inactive ingredients? In other
words, what might be the purpose of including the other ingredients?
Definition: percent: in the
hundred; of the hundred.
E.g. if you get a 75% on
an exam, then you
answered 75 of the 100
test questions correctly
Synonym:
The formula is like a
recipe. In other words, an
adult formula is made
from a different recipe
for the drug as a
children’s formula. Your
family might use different
recipes to make their
meals than another
family uses.
Definition: inactive- not
active
Explore it - III:
While some drugs are given as pills of dry powder, others are given as
liquids.
1) Why might it be important or useful to make a medication into a liquid
as opposed to a pill?
Synonym
The word opposed has
the same meaning as
‘instead of’ in this
context.
2) How might you turn a dry powdered medication into a liquid form of the
medication?
3) Try making liquid Gatorade from powdered Gatorade using your
procedure from number 2. Watch what happens to the powder and record
your observations here.
Extra information:
Gatorade is the brand
name (company name) of
a drink that many
athletes drink when they
are playing sports in
order to put water back
in their bodies.
Discuss it - III:
1) Discuss with the class the results of your Gatorade experiment. Try to
come up with a scientific term to describe the end result.
*Try describing this in
your native language,
then use a translation
tool to see if you can
come up with the English
word.
2) When we dissolve one substance into another substance we can use
scientific terms to identify each one. The substance that is being dissolved
is called a solute and the substance in which the solute is dissolved is called
the solvent. In your Gatorade example from above, identify which
substance was the solute and which substance was the solvent.
Synonym:
The word ‘substance’ is a
general term to describe
a material or ingredient.
Solute: ______________________________
Solvent: _____________________________
3) If you added more Gatorade powder to your solution, what would that
do to the concentration of that solution? (Hint: imagine how it would taste
compared to the original solution- DO NOT ACTUALLY DRINK THE
SOLUTION)
4) If you added more water to your original Gatorade solution, what would
that do to the concentration of the solution. (Hint: again, imagine how it
would taste compared to the original solution- DO NOT ACTUALLY DRINK
THE SOLUTION)
5) Write an equation that shows how the words solute, solvent and
solution are related.
Definition: concentration:
the strength of a
solution; how much of a
substance is found in a
liquid.
Explore it - IV:
While we can describe the concentration of a solution as high or low, when
applying this information to drug dosage, it is important to be more
precise. One way that we can express the strength of a concentration is by
calculating a mathematical expression called percent solution. We know
that a percent is a way to represent ‘parts per 100;’ percent solution just
applies this idea to solutions by describing the amount of solute in 100 mL
of total solution as a percent.
We use volume (in milliliters, abbreviated mL) as the unit of measure to
describe how much total solution is present. However, because solutes are
not necessarily liquid, we can use either weight (in grams, abbreviated (g)
or volume (mL) to describe how much solute is present; therefore, we use
two different formulas to calculate percent solution depending on the state
of matter of the solute. For example, some people use liquid laundry
detergent while others use a powdered detergent. If someone switched
between a liquid and powdered detergent, but still wanted to have the
same strength of detergent, they could use percent solution calculations to
ensure that they can keep it consistent.

Weight/volume (W/V) percent solution
o A mathematical expression to compare a solid solute
(g) to 100 mL: of the total solution.
o Formula: ____Mass of solute (g)_____ x 100
Volume of solution (mL)

Volume/volume (V/V) percent solution
o A mathematical expression to compare a liquid
solute (mL) to 100 mL: of the total solution.
o Formula: ____Volume of solute (mL)__ x 100
Volume of solution (mL)
It is important to note that for both formulas, we are using the total
volume of the solution, not just the volume of the solvent. Recall the
equation from part two that you used to relate solute, solvent and solution.
To further demonstrate the difference between the volume of the solvent
vs. the volume of the whole solution, try the following and record your
observations in the chart below.
Definition: abbreviated:
something that has been
made shorter. For
example, we made the
word milliliters shorter by
writing only mL to
represent the idea.
Definition: formula: a rule
or equation written with
letters and numbers.
**Formula is used in a
different context than it
was previously in this
activity. Now formula is
talking about a
mathematical equation
to determine percent
solution as opposed to
describing a recipe as
before.
Obtain the following from your teacher:
Salt
Water
100 mL Beaker
100 mL Graduated Cylinder
Scale
Weigh boats
Procedure:
1) Weigh out 5 grams of salt and pour the salt into the
empty beaker.
2) Measure out 100 mL of water in the graduated
cylinder.
3) Slowly pour water from the graduated cylinder into the
beaker until the total solution in the beaker reaches
100 mL. How much water did you use? Record your
data in the chart below.
4) Empty your supplies and repeat steps 1-3 two more
times using 10g and then 20 grams of salt. Record your
data in the chart below.
Grams of solute
mL of solvent
Total volume of
solution
5
10
20
Discuss it - IV:
Use your data above to answer the following questions:
1) The total volume of the solution is the same for all three trials, but the
amount of solvent used to produce that volume of solution is different.
Explain why this occurred.
2) Which two columns would you use from the chart above to calculate the
percent solution for the three trials? Explain how you would use the data.
3) If our solute was a liquid instead of a solid, how would your percent
solution calculations differ?
Extra information:
A beaker is often glass
and almost looks like a
glass you would drink out
of. It often has a dip in
the edge that can be used
to pour liquid and will
also have lines along the
side to indicate how
much liquid is in the
beaker.
A graduated cylinder is
generally a tall, thin piece
of equipment that has
many lines or
‘graduations’ along the
side to show how much
liquid is in the container.
Apply it:
You have learned a lot about how the vocabulary involved in understanding
and calculating the strength of a solution (the concentration), now let us
apply it to drug dosage calculations that you might use as a healthcare
professional.
1) Your patient is extremely dehydrated, so you decide to administer
2000mL of a 12% saline solution to help rehydrate them. This is a common
solution used in hospitals for this purpose that is made out of salt and
water. How would you make this solution? Write using complete sentences
and show your calculations.
2) In the solution described in number 1 above, which substance is the
solvent and which is the solute?
3) How many grams of ampicillin (an antibiotic) would you need to prepare
500 mL of a 20% solution of antibiotic and water? Show your calculations
and be sure to use the correct units.
4) Your patient needs 50 mL of antibiotic, but the antibiotic must be diluted
to a 10% solution in water in order for the patient’s body to process it
correctly. How much water would you need to add and what would the
total volume of solution would you end up with. Show your calculations
and be sure to use the correct units.
Definition: rehydrate: to
put fluid or liquid back
into something.
**whenever you see a
word with ‘hydra’ or
‘hydro’ in it, think water!
5) You have 10 g of a powdered antibiotic and you need to make a 30%
solution; you need to add water to dilute it. What will be the volume of the
final solution? Show your calculations and be sure to use the correct units.
6) A patient has been hooked up to an IV containing 1000mL of a 5%
solution of antibiotic. The patient falls asleep and the IV falls out after only
600 mL have been administered. How much of the antibiotic (in mL) has
the patient received? Show your calculations and be sure to use the correct
units.
Expand it:
If all this is making sense, check out some resources to find out more about
how doctors and other health professionals apply this type of information!
Do some research either in a medical text book or using reputable internet
sources to find more information to answer any of the following questions.






How are IV solutions made commercially?
How do IV pumps work.
How can ‘percent solutions’ be applied to hemodialysis?
What is a ‘gel cap’?
How are dosing guidelines determined?
What other ways can medication be administered besides in
pill or liquid form? Are they produced in similar ways?
Extra Information:
An IV is a tool that
doctors use to inject
liquid into someone’s
body. The doctor will put
a needle into someone’s
blood vessels (veins and
arteries) and will use that
to get liquids into the
body.
Assess it:
Problem: You are working as a researcher for a pharmaceutical company
who is developing antibiotic treatments for hospitals. Your boss as put you
in charge of a project to find the minimum dosage of an antibiotic that is
effective in getting rid of a bacterial infection. You will be setting up an
experiment to test out various percent solutions of two different antibiotics
to determine how you can make the cheapest, yet most effective antibiotic
solution so sell to hospitals. The two antibiotics that you will test are
Kanamycin and Ampicillin. The Kanamycin is $100.00 for 5 grams of
powder, while the Ampicillin is $200.00 for 5 grams of powder. In other
studies that you have done, you have found that you do not need more
that a 50% solution of either antibiotic to kill off susceptible bacteria.
You will need to design an experiment with the following components: 1)
Introduction/background, 2) hypothesis and predictions, 3) experimental
design/procedure, 4) data, 5) conclusions. Follow this format and fill in your
experiment below.
1) Introduction/background: Provide a brief background for your
experiment. Use what you have learned in this lesson as well as
information from reliable internet or book sources.
2) Hypothesis/predictions:
3) Experimental design/procedure: Explain how you will test your idea. Be
sure that you include experimental (treatment) groups and at least one
control group. Describe the actual procedure that you will use. Feel free to
draw pictures to help describe the design, but be sure to label them.
4) Data: Explain what data you will collect. Be sure to include details such
as what units you will use and how the data will allow you to answer your
question. Explain how you will organize your data in order to analyze it.
5) Conclusions: Explain how you will analyze your data and provide
examples of possible scenarios or outcomes along with an interpretation of
what that outcome would mean for your question. In other words, describe
how you will use the data to pick the antibiotic solution that fits the task
that your boss at the pharmaceutical company gave you. After you have
completed this task, brainstorm other ideas besides increasing the percent
solution of an antibiotic to kill more bacteria; what other approach(es)
could you use to create drug solutions to help patients fight off their
infection?