MOLLOY UNIVERSITY
THE BARBARA H. HAGAN SCHOOL
OF NURSING AND HEALTH SCIENCES
LEVEL 1
DRUG CALCULATION
PRACTICE PACKET
Fall 2023
2
Table of Contents
Objectives/Exam Content………………………………………………………………………..
Rounding rules………………………………………………………………………………………..
Conversion table……………………………………………………………………………………..
Military time vs Civilian time……………………………………………………………………
Measurement Accuracy…………………………………………………………………………...
Conversions from one system to another and within a system…………………..
Oral medications (tablets and liquids)……………………………………………………...
Reconstitution and Injectable Medications ………………………………………………
Weight based and safe dose ranges based on weight…………………………………
IV’s, IVPB, LIB, Time to complete, gravity vs. volumetric pump…..……………...
Mixed problems for review………………………………………………………………………
3
4
5
6
7
10
13
19
23
26
30
3
OBJECTIVES
LEVEL 1 DRUG CALCULATION PROFICIENCY EXAMINATION
Objective #1: The student will calculate the following with an accuracy of 90%
or better:
a.
Conversions between the apothecary system and the metric system.
b.
Conversions within the metric system (mcg to mg, g, mL, l, etc.) and
apothecary system (teaspoon to tablespoon, ounces to pounds, etc.)
c.
Conversions between common time (am, pm) and military time.
d.
Conversions of fractions to decimals and vice versa.
e.
Number of pills or volume of liquid to administer the medication dose as
prescribed (oral, intramuscular, subcutaneous, intravenous, etc.)
f.
Dose of weight-based medications and amount or volume to be administered.
g.
Safe dose range of medications based on weight and decide whether the dose
ordered is subtherapeutic, therapeutic, or toxic.
h.
Rate to administer intravenous fluids on gravity drip and volumetric pump.
i.
Amount left in bag of IV fluid at a specific time, and time when completed.
j.
Total amount of insulin to withdraw when mixing NPH and regular insulin in
the same syringe.
Objective #2: The student will demonstrate the ability to do the following with
an accuracy of 90% or better:
a.
Interpret standard abbreviations for weights and volumes.
b.
Select the essential information on a medication label needed to calculate
the correct dose or volume to administer as per prescriber’s order.
c.
Apply calculation methods appropriate to the problem.
d.
Use leading zero and remove trailing zero as appropriate for decimals.
e.
Round all calculations to the 10ths unless under 1, then round to 100ths.
f.
Round kg to the nearest 10th before proceeding with calculations, only if
if specified in the question. Otherwise do not round until the end.
g.
Round drops to the nearest whole number.
h.
Round numbers below 5 down and 5 or above up as appropriate.
i.
Recognize that the volume of an IM injection should usually be 3 mL or less.
j.
Recognize when a volume (pills, liquids, rate) calculated is unrealistic, and
recalculate as needed.
k.
Choose the correct amount of diluent to reconstitute a medication accurately.
l.
Choose the correct concentration of medication to use for a specific route.
m.
Choose the correct equipment to administer the most accurate dose based
on the volume and type of medication.
n.
Differentiate between the amount of a divided dose and total dose per day.
o.
Remember the correct procedure for mixing NPH and regular insulin in
the same syringe.
p.
Read a sliding scale and select the correct dose of medication as indicated
by the parameters specified (ie. dose of insulin based on blood glucose; dose
of medication based on body weight.)
4
MOLLOY UNIVERSITY
The Barbara H. Hagan School of Nursing and Health Sciences
Undergraduate Program
CALCULATION INSTRUCTIONS:
1. Write out your math. Later, it will help to identify errors if you can see everything
you did.
2. Round your answer at the very end of the calculation unless otherwise specified.
ROUNDING RULES ARE AS FOLLOWS:
PARENTERAL
Intravenous infusion by gravity (gtts/min): round to the nearest whole number
Intravenous infusion by pump (mL/hr): round to the nearest tenth of a mL
Injectable medications:
•
For any volume less than 1 mL, round to the nearest hundredth
•
For any volume greater than 1 mL, round to the nearest tenth
ENTERAL
Oral/NGT/PEG/J Tube:
•
For any volume less than 1 mL, round to the nearest hundredth
•
For any volume greater than 1 mL, round to the nearest tenth
WEIGHT
POUNDS TO KILOGRAMS CONVERSIONS: round to the nearest tenth
•
Round lb to kg conversions to the nearest tenth for adults. Do not round kg within a
problem unless specifically instructed to do so.
DOSE CALCULATIONS (g, mg, mcg)
•
Dose calculations may be rounded to the nearest tenth unless otherwise specified
LEADING AND TRAILING ZEROS
•
If a number begins with a decimal point, use a leading zero.
•
Do not use a trailing zero with a decimal.
5
Rounding rules updated summer 2023.
CONVERSION TABLE
METRIC
APOTHECARY
HOUSEHOLD
Volume:
1 milliliter (mL)1
15 minims (M)2
15 drops (gtts)
5 milliliters (mL)
1 fluidram2
1 teaspoon (tsp) (t)
15 millititers (mL)
1 tablespoon (tbsp.) (T)
30 milliliters (mL)3
1 fluid
ounce (oz)3
2 tablespoons (tbsp.) (T)
500 milliliters (mL)
1 pint (pt)
2 cups3
1000 milliliters (mL)
Weight:
1 milligram (mg) = 1000 micrograms
1 quart (qt)
1/60 grain (gr)2
60 milligrams (mg)
1 grain (gr)2
65 milligrams (mg)
1 grain (gr)2
1 gram (g) = 1000 milligrams (mg)
30 grams (g)
1000 grams (g) = 1 kilogram (kg)
Length:
10 millimeters(mm)=1 centimeter(cm)
15 grains (gr)2
1 ounce (oz)
16 oz = 1 lb
2.2 pounds (lb)
1 inch
2.54 centimeters (cm)
≈ 1 yard
100 centimeters = 1 meter (m)
1
Note: 1 milliliter (mL) = 1 cubic centimeter (cc), which is no longer recommended.
Note: Minims, drams, and grains are no longer used but may persist on some labels or in
some practice problems. They no longer appear on the N-Clex.
3
Note: The conversion from Metric to Apothecary and Household is approximate. These
2
6
are generally accepted and are standard for the health care field.
Updated summer 2023.
MILITARY TIME
Hospitals use military time to avoid confusion between AM and PM.
In standard civilian time, after the clock strikes 12 noon, the time becomes PM. You may
have a 1 AM or 1 PM. In military time, after the clock strikes 12 noon, the time
continues to add to the total until 12 midnight. Thus, 1 AM is 0100 hours, but 1 PM is
written as 1300 hours. When the clock strikes 12 midnight and the day changes to the
next day, the count is reset to zero. 12:01 AM would equal 0001 hours in military time.
See the chart below for the full comparison. Note that there is no 2500 hours. The time
resets after 2400 hours. When calculating when an IV will be finished, be sure to include
the full amount of time. For example, if an IV starts at 2200 hours (10 pm) and is to run
for 12 hours, it will be finished at 1000 hours (10 am), NOT 0959 hours. If you are
working an 8-hour shift and start at 1500 hours (3 pm), you have not completed your shift
until 2300 hours (11 pm). If you clock out at 2259 (10:59 pm) your boss will be upset.
Civilian Time
1 AM
2 AM
3 AM
4 AM
5 AM
6 AM
7 AM
8 AM
9 AM
10 AM
11 AM
12 PM
1 PM
2 PM
3 PM
4 PM
5 PM
6 PM
7 PM
8 PM
9 PM
10 PM
11 PM
12 PM
12:08 AM
1:07 AM
Military Time
0100 hours
0200 hours
0300 hours
0400 hours
0500 hours
0600 hours
0700 hours
0800 hours
0900 hours
1000 hours
1100 hours
1200 hours
1300 hours
1400 hours
1500 hours
1600 hours
1700 hours
1800 hours
1900 hours
2000 hours
2100 hours
2200 hours
2300 hours
2400 hours
0008 hours
0107 hours
7
ACCURATE MEASUREMENT OF DOSES CALCULATED
An accurate calculation is essential for administering the correct dose of a
medication but will not result in the desired amount being delivered to the patient
unless the measurement of the dose to be administered is accurate as well. Nurses
may be tested on the following guidelines:
Medications in solid form:
1.
Avoid breaking tablets whenever possible. Breaking a tablet is less desirable
than administering a whole tablet in the correct dose. Breaking a tablet
reduces the accuracy of the dose. Do not break a tablet in half unless it has a
score line. Generally, tablets can only be broken in half, but there are a few
tablets that are scored to be broken into quarters. Use a pill splitter or cutter
whenever possible. 1/8 or less of a tablet is impossible, so check calculations.
Liquid oral medications:
1.
Always choose the most accurate measuring device. Teaspoons/ tablespoons
are the LEAST accurate because they vary from one set to another.
Teaspoons should be avoided if possible.
2.
Other devices include medicine cups,
medicine spoons, and oral syringes.
3.
Liquid medications in medicine cups
should be measured at eye level. The
bottom of the meniscus (surface curve) should be level with the dose desired.
Above: not a full 2 tsp.
4.
Above: Accurate measurement.
Liquid medications in medicine spoons should be held vertically at a 900
angle at eye level for accurate measurement.
8
5.
The most accurate way to measure oral liquid medications is in an oral
syringe. An oral syringe has an elongated tip rather than a screw tip. It cannot be connected to an intravenous device by accident. It is sometimes
orange. Oral medications should never be placed in syringes with screw tips.
Oral medications should always be labeled “For oral use only.”
Above: oral syringe with elongated tip.
Choosing correct size and measuring medications in syringes:
1.
Intramuscular (IM), subcutaneous (SC), and intradermal medications are
measured in syringes with a screw tip which can accept a needle.
Intravenous medications usually need a needle-less syringe that is
compatible with the intravenous equipment in use at the institution. Oral
medications should use a syringe with an elongated tip as above.
2.
Insulin MUST be measured in insulin syringes that are
marked in units. The syringe selected must be in the same
concentration as that of the insulin being used. (For example,
U-100 insulin, U-100 syringes. They hold 100 units per mL or
50 units per 0.5 mL or 30 units per 0.3 mL.) After choosing the
correctly calibrated syringe, choose the syringe size that is
closest to the amount of insulin to be administered for greatest
accuracy. (Right: 100-unit, 50-unit, and 30-unit syringes for U100 insulin. For 36 units, pick the 50-unit syringe.)
3.
Choose a syringe that is as close to
the amount to be administered as
possible while still allowing a small
amount of room to adjust the
plunger. The smaller the syringe,
the more accurate the measurement.
Liquid amounts under 1 mL should
be measured in a TB (tuberculin)
syringe, which is measured in
increments of 0.01 mL. Over 1 mL to
2.9 mL may be measured in a 3 mL
syringe, which is measured in 0.1 mL
increments, etc.
9
4.
All syringes measure liquid from the base of the tip to the first ring of the
plunger.
5.
Some practice examples:
A.
Which one of the following syringes would be
the best choice to administer 1.9 mL of fluid
IM?
Answer: 3 mL syringe. It is the closest to the
does to be administered. 5 mL is less
accurate.
B.
How much fluid is in this syringe?
a.
4.3 mL
b.
4.6 mL
c.
5.4 mL
d.
5.7 mL
Answer: 4.6 mL. The syringe is in 0.2
mL increments. The liquid is measured
from the base of the tip (left) to the first ring or platform of the
plunger.
C.
Which of the syringes shown at right would be the
best choice to use to administer 47 units of U-100
insulin?
a.
The 100-unit syringe on the left.
b.
The 50-unit syringe in the middle.
c.
The 30-unit syringe on the right.
Answer: The 50 unit syringe. It is as close to 47
units as it can be and still leave a bit of room to
adjust. The 100 unit syringe is less accurate.
10
MOLLOY UNIVERSITY
BARBARA H. HAGAN SCHOOL OF NURSING
Nur 2390
Instructor: Mary E. Fassetta, EdD, RN
Conversions
Conversions
Solve the following:
1.
The patient weighs 185 pounds. How many kilograms does he weigh?
2.
A baby weighs 3.6 kilograms. How many pounds does she weigh?
3.
The label on the medication bottle says to take 2 teaspoons. How many
milliliters should be dispensed?
4.
A coffee cup contains 6 fluid ounces. How many milliliters should the nurse
record on the Intake and Output record?
5.
The bottle of aspirin says that one tablet equals 5 grains. How many
milligrams are in one tablet?
6.
The patient is to receive 2.5 liters of IV fluid in 24 hours. How many
milliliters is this equal to?
7.
The medication label states that each pill contains 150 micrograms of
medicine. How many milligrams is this equal to?
11
Converting from one system to another:
1.
Identify the conversion that will be used on the conversion chart.
2.
Set up a ratio and proportion equation. For instance, if 1 teaspoon equals 5
milliliters, how many milliliters do 3 teaspoons equal?
1 teaspoon = 5 milliliters
3 teaspoons X milliliters
or
1 teaspoon = 3 teaspoons
5 milliliters X teaspoons
(Notice how the 1 t and 5 mL are either on the same line or the same side, so they
stay together as equal, and the 3 t and the X mL do the same. Similarly, you must
compare t to t and mL to mL, so they need to either be on the same side or the same
line.
3. ERROR ALERT! Be careful not to flip one of the sets. If you make 1 t equal X mL
or 3 t equal 5 mL it will be wrong.
4.
Get the equation all on one line by cross-multiplying, as in Homework #1.
1t
3
5 mL becomes 1X = 3 x 5 so that X =15 mL
X mL
5.
Notice that because the conversion is in the form of 1 t = 5 mL, it is easy to see
that 3 t would just equal 3 x 5, or 15 mL. Experienced nurses often do this type of
math without setting up the ratio and proportion. However, when dispensing
medications, the equivalents are often given in numbers other than 1, so setting up
the ratio and proportion is an important step.
6. Another method for doing these problems may be simpler to understand. It is a
formula method. D stands for desired, or what you are looking for. H stands for
have, or what you already know. In this case, it would be the conversion factor.
Some books use V to stand for liquid volume or Q to stand for quantity. We could set
up the equation this way:
Desired x Quantity = X
Have
3 t x 5 ML = 15 mL = X
1t
Notice that if the equation is set up correctly, the labels (t on top and t on bottom)
will cancel each other out, and the answer will be in mL, which is what you are
looking for. Both of these methods can be used with almost any dose problem.
12
Answers:
1.
84.1 kg 2.2 lbs = 1 kg
2.
7.9 lbs
3.6 kg/x lb = 1 kg/2.2 lb. 3.6 x 2.2 = 7.92 round to 10th = 7.9
Note* This does NOT mean 7 lbs 9 oz. If there are 16 ounces in a pound,
0.9 lb = 9/10 of a lb, or 14.4 ounces. If the question asked for pounds and
ounces, an additional conversion would be required.
3.
10 mL
4.
180 mL 1 fl oz = 30 mL
5.
300 mg OR 325 mg. Note that grains are no longer used, in part because they
are not a uniform measure. Older medications such as aspirin often used the
conversion of 65 mg to 1 grain, so 5 x 65 = 325 mg. A “cardiac dose” of
aspirin is 81 mg, or ¼ of a 325 mg tablet. Most newer medications do not use
this conversion. Codeine, for instance, uses 60 mg = 1 grain. Thus, ½ gr of
codeine equals 30 mg. If we used the 65 mg = 1 grain conversion, ½ gr of
codeine would be 32.5 mg, which is a very odd number. Luckily, products
that are old enough to be measured in grains (such as nitroglycerin) are
always labeled in milligrams as well. This question is just to bring this to your
attention. Grains are not required for the N-Clex examination, but it is
possible that a nurse may see them somewhere. It is also good to note that gr
means grains and g or G means grams.
6.
2500 mL
7.
0.15 mg
1 mg = 1000 mcg To multiply decimals, move the decimal point
to the right. To divide, move the decimal point to the left by the number of
zeros in the conversion. 150 mcg/X mg = 1000 mcg/1 mg
150/1000 = 0.15 mg. Add a leading zero to alert the reader to a decimal
point. Remove a trailing zero to avoid confusion.
1 tsp = 5 mL
185 lb/x kg = 2.2 lb/1 kg = 84.0909 round to 10th
2 tsp/X mL = 1 tsp/5 mL 2 x 5 = 10 mL
X mL/6 oz = 30 mL/1 oz 6 x 30 = 180 mL
1 Liter = 1,000 mL
2.5 L x 1,000 mL = 2,500 mL.
Revised 6/29/2023
13
MOLLOY UNIVERSITY
BARBARA H. HAGAN SCHOOL OF NURSING
Nur 239 Pharmacology I
Instructor Mary E. Fassetta, EdD, RN
Oral Med Doses
Calculating Oral Medication Doses
40 mg
valsartan
30 Tablets
Rx only
Suffern, NY 10901
Diovan
Dispense in tight container
(USP). 85081801
Dosage: See package insert
Store at 25o C (77o F)
Excursions permitted to
15-30o C. (59-86o F)
Protect from moisture.
NDC 0078-0376-15
Novartis Pharmaceuticals
The prescriber orders Diovan 120 mg by mouth once a day for a patient. The
drug available is labeled as follows:
EXP. 1/25/23
LOT # 57135247
1.
How many tablets should the nurse administer to the patient per dose?
(Tablets are scored.)
___________tab(s)
The prescriber orders Lotrel 5 mg/20 mg by mouth once a day for a patient.
The drug available is labeled as follows:
EXP. 7/15/23
Lot # 127598-03
Distributed by Novartis
Pharmaceuticals, Suffern, NY
10901
NDC 0078-0404-05
Lotrel
2.5/10
amlodipine besylate
(equivalent to amlodipine 2.5 mg)
benazepril HCL 10 mg
100 Capsules
Rx only
Dosage: See package insert.
Store at 25o C (77o F)
Dispense in tight container.
Keep this and all medications
out of the reach of children.
2.
How many tablets should the nurse administer to the patient per dose?
(Tablets are scored.)
_____________tab(s)
14
3.
The prescriber orders Diflucan 0.4 g by mouth once a day for the patient.
The drug available is labeled as follows:
Store below 86o F (30o C)
Dosage and Use
See accompanying
prescribing information.
Each tablet contains
100 mg fluconazole
MADE IN USA
Rx onl y
NDC 0049-3420-30
30 Tablets
Diflucan 100
(Fluconazole Tablets)
100 mg
3 N 0049-3420-30
05-4671-32-4
Exp. July 15, 2023
Pfizer/Roerig
How many tablets should the nurse administer to the patient per dose?
(Tablets are scored.)
____________tab(s)
4.
The prescriber orders Tikosyn 0.5 mg by mouth twice a day for the patient.
The drug available is labeled as follows:
Store at controlled room
temperature 150 tto 300 C
(590 to 860 F)
PROTECT FROM MOISTURE
AND HUMIDITY
Dispense in tight containers
(USP).
DOSAGE AND USE
See accompanying
prescribing information.
Each capsule contains 125
mcg dofetilide.
NDC 0069-5800-60
60 Capsules
Rx only
Tikosyn
(dofetilide)
125
7400
MADE IN USA
EXP. 10/22/23
0069-5800-60
05-5549-32-2
125 mcg
__________________
Pfizer Labs
How many capsules should the nurse administer to the patient per dose?
______________cap(s)
No. 3376
Contains no aspirin
Pain reliever
Fever reducer
100 TABLETS – 325 mg each
NDC 0006-3376-66
237 mL
ORAL SUSPENSION
INDOCIN
(INDOMETHACIN)
25 MG PER 5 ML
SHAKE WELL BEFORE USING
ALCOHOL 1%
Rx only
Exp. 12/22/2023
ACETAMINOPHEN
Lot
PAIN RELIEF TABLETS
Directions: Do not take more than
directed (see Liver warning)
Adults and children 12 years and older:
Take 2 tablets every 4 to 6 hours while
symptoms last. Do not take more than 12
tablets in 24 hours.
Children 6 to 12 years of ace: take 1
tablet every 4 to 6 hours while symptoms
last. Do not take more than 5 tablets in 24
hours.
Children under 6 years: Do not take adult
strength product. This will provide more
than the recommended dose (overdose)
REGULAR STRENGTH
Inactive ingredients: antifoam AF emulsion,
flavors, purified water, sodium hydroxide or
hydrochloric acid to adjust pH, sorbitol solution,
and tragacanth. Sorbic acid 0.1% added as
preservative.
6.
237 mL
5.
USUAL DOSAGE: see accompanying circular,
Keep container tightly closed. Protect from
freezing. Store below 300 C (86o F)
Avoid temperatures above 50o C (1220 F).
15
The prescriber orders Tylenol (acetaminophen) X gr by mouth q4h PRN for
headache for the patient. The drug available is labeled as follows:
How many tablets should the nurse administer to the patient per dose?
(Tablets are scored.)
___________tab(s)
The prescriber orders Indocin (indomethacin) 150 mg by mouth daily in 3
divided
doses. The drug available is labeled as follows:
How much should the nurse administer per dose?______mL Per day? ______mL
How many tsp should the patient receive per dose? _____tsp Per day? _____tsp
16
7.
The prescriber orders Norvir (ritonavir) 0.03 g by mouth q12h for a pediatric
patient. The drug available is labeled as follows:
NDC 0074-1940-63
240 mL
NORVIR
(RITONAVIR ORAL SOLUTION)
80 mg per mL
Shake well before each use.
DO NOT REFRIGERATE
Use by product expiration date
ALERT!
Find out about medicines that should NOT
be taken with NORVIR.
Place a mark on the syringe below to indicate how many mL the nurse should
administer to the patient.
17
8.
The prescriber orders Atarax 50 mg by mouth now for a patient with an
allergic reaction. The nurse discovers two medications in the patient’s draw
that are labeled as follows:
Which medication should the nurse administer to the patient? How did you know?
Reading medication labels:
1.
Medication labels can be confusing and distracting! When calculating doses,
ALWAYS look for the equivalent – how many milligrams, etc. in how many tablets or
mL. Use the formula: desired (or dose ordered) X the quantity (it comes in) = dose
have (dose it comes in)
2.
If the order and the label are not in the same measurement, you must convert
one of them before you can begin. For instance, if the order is in grams and the drug
label is in milligrams, convert the grams to milligrams before you begin. If the order
is in grains and the label is in milligrams, convert the grains to milligrams first, then
use the formula. Many drugs come with both measurements already on the label.
3.
The dose should always make sense! If the nurse is administering more than
3 pills, the calculation should be rechecked. Oral liquid doses vary, so check sources.
18
1.
3 tablets. Desired/have x vehicle = 120 mg/40 mg x 1 tab = 3 tabs.
2.
2 tablets. This is a combination medication. The proportions of each
medication cannot be changed, so it is acceptable to use one medication
for calculations, as long as they are not mixed up! So, if there are 2.5 mg
of amlodipine in the pill, and the order is for 5 mg, it can be calculated as
5 mg/2.5 mg x 1 tablet = 2 tablets.
3.
4 tablets. First note that 0.4 g and 100 mg are not in the same units. There
are 1,000 mg in 1 g, so 0.4 g = 400 mg. Then it is easy to see that 100 mg x 4
tablets = 400 mg dose. You can also use desired/have x vehicle =
400 mg/100 mg x 1 tablet = 4 tablets. That is about the maximum usually
given. If a dose exceeds 4 tablets, recheck your calculations for safety. There
are rare exceptions to the rule. Always check a reliable drug source when in
doubt.
4.
4 capsules. 0.5 g = 500 mg
5.
2 tablets.
Although grains are no longer used, this can be for practice.
X gr = 10 grains in Roman Numerals, which is the way grains were listed.
If 1 grain = 60 mg, 10 grains = 600 mg. But Tylenol is so old, it uses the
1 grain = 65 mg conversion. That is why tablets are 325 mg each. If we use
the 325 mg/x grain = 65 mg/1 grain conversion, we discover that 1 tablet =
5 grains, so 2 tablets equal 10 gr, or X gr. As you can see, lots of room for
mistakes, which is why grains are no longer used.
6.
150 mg divided by 3 doses = 50 mg per dose, or 10 mL or 2 tsp/dose.
50 mg/25 mg x 5 mL = 10 mL per dose. That equals 2 tsp per dose. 1 tsp = 5
mL 2 tsp = 10 mL.
A patient would receive a total of 30 mL/day, or 6 tsp. The pharmacist would
need to know that to know how long the bottle will last and give the patient
enough medicine for the duration of treatment, or one month.
7.
0.38 mL Convert 0.03 g into 30 mg by moving decimal 3 places right. Then
use d/h x volume = 30 mg/80 mg x 1 mL = 0.375 round to 0.38 mL.
8.
Hydroxazine HCL is Atarax. A nurse would need to look up the Brand name
and find out what the generic name is. Hydralazine is to lower blood
pressure , and hydroxazine is for allergies and inducing drowsiness. The
medication must make sense for the patient as well. These are two actual
labels from the same company. It would be very easy for these two meds to
be confused. Constant vigilance is needed to prevent mistakes.
500 mg/125 mg x 1 capsule = 4 capsules
Revised 6/29/2023
19
MOLLOY UNIVERSITY
BARBARA H. HAGAN SCHOOL OF NURSING
NUR 2390
Instructor: Mary E. Fassetta, EdD, RN
Reconstitution & Injectables
Reconstitution and Injectable Medications
1.
The physician orders 500 mg of a medication. The reconstitution directions
say to add 6.2 mL of sterile water to yield a concentration of 450 mg/mL.
What should the nurse administer to the patient? ____________________mL
2.
The physician orders 400 mg of a medication. The reconstitution directions say to
add 7.2 mL of sterile water to yield a concentration of vial read 650 mg/mL.
How many mL should the nurse administer to the patient? _____________mL
3.
The patient is to receive 300,000 units of a medication. The reconstitution
directions read:
1.
Add 5.5 mL to yield a concentration of 600,000 units/mL
2.
Add 6.3 mL to yield a concentration of 400,000 units/mL
3.
Add 7.6 mL to yield a concentration of 200,000 units/mL
A.
Which concentration should the nurse choose?___________________Why?
B.
How much diluent should the nurse add to the vial?__________ mL
C.
How many mL should the nurse administer to the patient?__________mL
20
4.
5.
The patient is to receive 400,000 units of a medication. The reconstitution
directions read:
1.
Add 6.5 mL to yield a concentration of 200,000 units/mL
2.
Add 5.3 mL to yield a concentration of 400,000 units/mL
3.
Add 4.6 mL to yield a concentration of 600,000 units/mL
A.
Which concentration should the nurse choose?_______________Why?
B.
How much diluent should the nurse add to the vial?___________mL
C.
How many mL should the nurse administer to the patient?__________mL
The prescriber orders Pfizerpen 2.5 million units IM Now. The available
drug is labeled:
Pfizerpen
(penicillin G potassium)
For Injection
FIVE MILLION UNITS
PFIZER ROERIG
USUAL DOSE:
Average single dose:
200,000 – 400,000 units
mL diluent
Units per mL
added
of solution
18.2 mL
250,000
8.2 mL
500,000
3.2 mL
1,000,000
Buffered with sodium citrate and
citric acid to optimum pH.
Recommended storage
in dry form.
Store below 860 F (300 C)
EXP 12/31/28
Division of Pfizer, Inc.
a.
The nurse chooses how to dilute this medication.
How much diluent should the nurse choose to add to the vial?
____________mL
b.
Based on the dilution above, how many mL of medication would the
nurse administer to the patient for this dose?
____________mL
21
Instructions:
1.
Reconstitution is needed when medications are stored as powders because
they are unstable as liquids. The label will indicate what solution to mix with the
powder. Usually, it is either sterile water or sterile 0.9% saline. The liquid that is
mixed with the powder is referred to as the diluent.
2.
If there is a choice to be made when reconstituting, the nurse may decide
which concentration to make based on two factors. If the route is not specified in
the problem, the nurse may choose the concentration that makes the math
calculations easiest. If the problem specifies an intramuscular (IM) injection, the
total amount of fluid to be administered to the patient may not exceed 3 mL.
3.
The amount of fluid added to the vial is specified in the instructions. Often,
the volume that results when the liquid is mixed with the powder is greater than the
amount of liquid added because the powder expands the liquid volume. Some labels
will specify the total amount in the vial after reconstitution is completed.
4.
If the nurse reconstitutes a multidose vial, it should be labeled with the
concentration and the date and time it was reconstituted. However, vials need
reconstituting because they do not store well as liquids and should not be used after
24 hours. Most vials are single use only, and any remaining medication should be
discarded according to institutional policy.
4.
ERROR ALERT! Once the liquid is added to the powder, the amount of
diluent is not used in the calculations. The nurse must know how many units or
milligrams are contained in how many milliliters (the concentration) to solve for the
dose to administer to the patient. The usual methods for solving dose problems are
used.
Answers:
1.
1.1 mL should be administered to the patient. When you reconstitute, just
follow the directions on the package and add the exact amount of diluent it tells you
to. Then, find the instruction that says how many mL are in how much fluid. In this
case, once the medication is mixed, there are 450 mg per one mL. Use the formula
desired/have multiplied by volume to find the answer. 5000 mg/450 mg x 1 mL =
1.1 mL. Use a leading zero to alert the reader to a decimal point.
2.
0.62 mL. See above for process. 400 mg/650 mg x 1 mL = 0.6153846 mL,
which should be rounded to the hundredths because it is less than 1 mL, so the
answer is 0.62 mL. Use a leading zero to alert the reader to a decimal point. Use a 1
mL or TB syringe to measure this dose, since it goes out to the hundredths.
22
3. First, look at the route. If it says “IM” then you need a dilution that will result in
a volume to be given to the patient of three mL or less. In this case, since there is no
route, you may choose the dilution that makes the math and the measuring the
easiest. The goal is to be consistent. Once you choose the dilution, follow the
directions for that dilution all the way through the problem. In the clinical area, be
sure to indicate on the bottle which dilution you are using if it is a multi-dose vial.
Remember, you do not do any math with the diluent amount. Once you have added
it to the bottle, do not use that number for anything else. Be sure to use a leading
zero for numbers under 1 mL and go out to the hundredths if needed. Here are the
calculations for all three options. In this case, they are all correct. The first choice is
easy to calculate and easy to administer.
1.
2.
3.
4.
Add 5.5 mL to equal 600,000 units/mL. Then, use desired/have x
volume to get: 300,000 units/600,000 units x 1 mL = 0.5 mL.
Add 6.3 mL to equal 400,000 units/mL. Use desired/have x volume:
300,000 units/400,000 units x 1 mL = 0.75 mL.
Add 7.6 mL to equal 200,000 units/mL. Use desired/have x volume:
300,000 units/200,000 units x 1 mL = 1.5 mL.
See instructions for #3 above.
1. Add 6.5 mL. Administer 2 mL.
2. Add 5.3 mL. Administer 1 mL. This is the easiest choice.
3. Add 4.6 mL. Administer 0.67 mL. This is the least accurate choice.
5. This question specifies IM, so the choice must be based on the volume to be
given to the patient. In this case, there is only one correct answer. You may have to
work out all of the choices before you can decide on the one you wish to use. This is
how you would decide:
1. Add 18.2 mL to create a solution of 250,000 units/mL. Using
desired/have x volume: 2,500,000 units/250,000 units x 1 mL = 10 mL,
which is too much for an IM injection.
2. Add 8.2 mL to create a solution of 500,000 units/mL. Using desired/have
x volume = 2,500,000 units/500,000 units x 1 mL = 5 mL, which is still too
much for an IM injection.
3. Add 3.2 mL to create a solution of 1,000,000 units/mL. Using
desired/have x volume = 2,500,000 units/1,000,000 units x 1 mL = 2.5 mL,
which is the only option that comes in under 3 mL for an IM injection. This
would be the correct answer.
Revised 06/29/2023
23
MOLLOY UNIVERSITY
BARBARA H. HAGAN SCHOOL OF NURSING
Nur 2390 Pharmacology 1
Instructor: Mary E. Fassetta, EdD, RN
Safe Dose Ranges
Weight Based Doses
Weight Based and Safe Range Dosing
Solve the following:
1.
The prescriber orders gentamycin sulfate 3 mg/kg/day IVPB in 2 divided
doses q12h for a patient weighing 161 pounds.
a.
How many kg dose the patient weigh?
________________kg
b.
How much medication should the patient receive per day? _____________mg
c.
How much medication should the patient receive per dose? ___________mg
ERROR ALERT! Wording is a source of confusion. Questions that ask for
mg/kg/day are calculating the total dose in a day. If it says to administer the
medication in divided doses, the nurse needs to divide the total for the day by the
number of doses requested. If the order is given in individual doses, like Question
#2, the nurse must multiply the amount per dose by the number of doses to
determine the total per day.
24
2.
The prescriber orders gentamycin sulfate 240 mg IVPB q12h for a patient
who weighs 172 lb. The safe dose range for gentamycin is 1 mg/ kg up to
5 mg/kg per day.
a.
How many kg does the patient weigh?
____________kg
b.
What is the lowest effective dose per day for this patient? ____________mg
c.
What is the highest safe dose per day for this patient?
____________mg
d.
What is the total dose per day ordered for this patient?
__________mg
e.
Based on the calculations above, is the dose ordered for this patient
within the safe dose range?
___________________
f.
Would the dose be considered subtherapeutic, therapeutic, or toxic?
________________
25
3.
The prescriber orders morphine sulfate 0.3 mg IM stat for a child who
weighs 68 pounds. The recommended dose is .01 mg per kg.
a.
How many kg does the child weigh?
_____________kg
b.
What is the recommended dose for a child of this weight?
___________mg
c.
Is this a safe dose for this child?
______________
The morphine sulfate on hand comes in a concentration of 0.5 mg per mL.
d.
How many mL should the nurse administer to the child if the dose is
determined to be safe?
____________mL
Answers:
1.
a. 73.2 kg. 161 lbs/2.2 kg = 73.181818 kg = 73.2 kg (round to nearest 10th)
b. 219.5 mg/ day. 73.181818 kg x 3 mg/kg/day = 219.54545 mg/day,
which is rounded to 219.5 mg/day.
c. 109.8 mg/dose. 219.54545 divided by 2 doses/day = 109.77272 or 109.8.
2.
a. 78.2 kg. 172 lbs divided by 2.2 lbs/kg = 78.181818 kg = 78.2 kg rounded
b. 78.2 mg/day. 78.181818 kg x 1 mg/kg/day = 78.2 mg/day rounded.
c. 390.9 mg/day. 78.181818 kg x 5 mg/kg/day – 390.90909 mg/day.
d. 480 mg/day. 240 mg/dose x 2 doses/day = 480 mg/day
e. No, it is above the maximum dose per day of 391 mg/day.
f. Toxic. The dose is too high for this patient.
3.
a. 30.9 kg
68 lb/2.2 lb/kg = 30.90909 kg = 30.9 kg
b. 0.31 mg 30.90909 kg x .01 mg/kg = 0.3090909 mg, or 0.31 rounded
c. Yes, 0.3 mg is safe. It is just below the dose calculated in b.
d. 0.6 mL. D/H x V = 0.3 mg/0.5 mg x 1 mL = 0.6 mL
Revised 06/29/2023
26
MOLLOY UNIVERSITY
BARBARA H. HAGAN SCHOOL OF NURSING
Nur 2390 Pharmacology I
Instructor: Mary E. Fassetta, EdD, RN.
1.
IV’s and IVPB’s
The prescriber orders an IV of D5NS to run at 125 mL an hour. The nurse has
IV tubing labeled 10 gtts/mL. How many drops per minute should the nurse
regulate the IV?
___________gtt/min
2.
3.
At 0900 hours the nurse hangs an IV with 1000 mL of D5RL to run at 75 mL
per hour.
a.
How much will be left in the bag (LIB) at 1500 hours? ______________mL
b.
At what time will a new bag need to be hung?
_________________hr
The prescriber orders a liter of D5 ½ NS to run over 12 hours. The tubing
available is labeled 15 gtts/mL.
a.
Using the available tubing, what should the drop rate for this IV be?
______________gtt/min
b.
If the nurse had a volumetric pump available, what would the nurse set
the pump for in mL/hr?
_____________mL/hr
27
4.
The prescriber orders an IV of NS at 25 mL/hr. The nurse chooses “minidrip”
or “microdrip” tubing for this IV. What is the drop rate for this IV?
__________________mL
5.
The prescriber orders Ancef 1 g in 50 mL of NS IVPB q6h. There are no
instructions regarding the amount of time to run the IVPB, so the nurse
chooses the standard time of 30 min for 50 mL.
a.
If the IVPB tubing is labeled 20 gtts/mL, at what rate should the nurse
run the IVPB on a gravity drip?
______________gtt/min
b.
If a volumetric pump is available, at what rate should the nurse set the
pump?
______________mL/hr
6.
The prescriber orders Vancocin (vancomycin hydrochloride) 1 g in 200 mL
NS over 2 hours IVPB q12h. The tubing is labeled 15 gtts/mL.
a.
At what rate should the nurse run the IVPB on a gravity drip?
_____________gtt/min
b.
If a volumetric pump is available, at what rate should the nurse set the
pump?
________________mL/hr
28
Instructions:
IV’s and IVPB’s are calculated using the same formula:
Volume (in mL)
Time (in min)
x
drops
mL
=
drops
min
If the formula is set up correctly, mL on the top an mL on the bottom will cancel each
other out and drops per minute are left. The problem must identify the gtts/mL.
ERROR ALERT! Volume MUST be in milliliters and time in minutes. If the problem
states liters, multiply by 1,000 milliliters per liter. If the problem states hours,
multiply the hours by 60 minutes. If the problem states a total volume (2 liters, for
instance) over a total time (24 hours, for instance) you can also change the liters to
milliliters and divide by hours to get the volume per hour, which will have smaller
numbers that may be easier to work with.
For IVPB’s, if there is no time specified on the label, the standard rate is 100 mL
per hour. Therefore, a 50 mL IVPB will take 30 minutes, a 25 mL IVPB will take 15
min, etc. If the time is specified, use the time in the standard formula above.
ERROR ALERT! Not all IVPB’s are run over 1 hour. Look for a time and use it in the
formula. For instance, if the order says to run a 25 mL IVPB over 20 min using a
minidrip, the formula method would look like this:
25 mL X
20 min
60 gtts = 1500 gtts =
mL
20 min
75 gtts
min
Or, the nurse could reason that 20 min x 3 = 60 min, so the rate would be 25 mL x 3,
or 75 mL per hour. When a minidrip tubing is used, the mL per hour always equals
the gtts per min. ERROR ALERT! It does NOT work to change 20 min into 0.333 hr
and multiply. 25 mL/0.333 hr = 75.08 mL because it is a repeating decimal. Keep the
formula in minutes.
When calculating how much is LIB (left in bag) at a certain time, note the amount
in the bag at the beginning of the question. Figure out how many hours have elapsed
since the original time and the stated time. Multiply the rate per hour by the
number of hours that have elapsed. This is how many mL’s were administered to
the patient. Subtract the number of mL’s administered to the patient from the
amount the question started with. This is how many mL’s are left in the bag.
ERROR ALERT! Do NOT start with the original amount and subtract the volume for
each hour until you come to the stated time. While it is possible to get the right
answer, the chance of error increases for each subtraction made.
29
When calculating when the bag will need to be changed, identify the mL per hour.
Divide the total mL in the bag by the mL per hour. This will be the total time the bag
will last. Locate the start time and use the number of hours the bag will last to
determine at what time the bag will need to be changed.
When determining how fast to run an IVPB on a volumetric pump (mL/hr) use a
ratio and proportion method and keep mL and minutes. For instance, if the order is
for 25 mL over 20 min, set it up like this:
25 mL = X mL
25 mL x 60 min = X ml x 20 min 1500 = 20 X 75 = X
20 min
60 min
Answers:
1.
21 gtt/min. 125 mL/60 min x 10 gtt/mL = 20.8333 = 21 gtt/min. Drops
should always be rounded to the nearest whole number.
2.
a. 550 mL LIB. 0900 to 1500 = 6 hr. 6 x 75 ml/hr = 450 mL used.
1000 mL bag – 450 mL used = 550 mL left.
b. About 10:20 pm, or 2220 hours. 1000 mL/ 75 mL/hr = 13.333 hr.
If the bag was hung at 0900, or 9 am, then it would last 13.33 hr, or
about 10:20 pm or 2220 hours. Acceptable answers would be 2200 hr,
2215 hrs, or 2220 hrs. 2230 is not acceptable, because the bag would be
empty for 10 minutes. Remember, 0.3 of an hour is not 10:30, it is 10:20.
If there are 60 minutes in an hour, then 1/3 of an hour is 20 minutes.
3.
a. 21 gtt/min. 1000 mL/720 min x 15 gtt/mL = 20.833 = 21 gtt/min.
b. 83.3 mL/hr. 1000 mL/12 hr = 83.3333 mL/hr. A pump can do tenths.
4.
25 gtt/min. Minidrip or microdrip is always 60 gtt./mL. 25 mL/60 min x 60
gtt/mL = 25 gtt/min. There is no real math involved. Rates over 50-60 mL an
hour should use a larger drop factor.
5.
a. 33 gtt/min. 50 mL/30 min x 20 gtt/mL = 33.333 gtt/min = 33 gtt/min.
b. 100 mL/hr. 50 mL over 30 min = 100 mL over 60 min. The IVPB will
still take 30 min to run in. A smart pump may be set for 50 mL in 30 min.
6.
a. 25 gtt/min. 200 mL/120 min x 15 gtt/mL = 25 gtt/min.
b. 100 mL/hr. 200 mL over 2 hr = 100 mL per hour.
Revised 06/29/2023
30
MOLLOY UNIVERSITY
BARBARA H. HAGAN SCHOOL OF NURSING
NUR 2390 Pharmacology I
Instructor: Mary E. Fassetta, Ed.D., RN.
1.
Mixed Review
The prescriber orders methadone hydrochloride 8 mg by mouth daily. The
medication is labeled as follows:
NDC 00054-3553-44
Nurse/Patient: Please note diagram
in package insert.
Fill dropper to the level of the
prescribed dose. For ease of
administration, add dose to
approximately 30 mL or more of juice
or other liquid. May also be added to
applesauce, pudding, or other
semisolid foods. The drug-food
mixture should be used immediately
and not stored for future use. Return
dropper to bottle after use. Discard
opened bottle after 90 days.
Protect from light.
METHADONE
HYDROCHLORIDE
INTENSOL
Oral Concentrate USP
10 mg per mL
Each mL contains methadone
hydrochloride 10 mg
Rx only
ROXENE LABORATORY
How many mL of medication should the nurse administer to the patient?
__________mL
The prescriber orders Avelox 0.4 g by mouth twice a day. The medication
available is labeled as follows:
30 tablets
Rx only
Printed in USA
Equivalent to
400 mg moxifloxacin
Distributed by
AVELOX
Moxifloxacin hydrochloride
Schering-Plough
Description: Each tablet contains
mociflocacin hydrochloride
equivalent to 400 mg of
mociflocacin. See accompanying
literature for complete
information on dosage and
administration
NDC 0085-1733-01
Byer Health Care
2.
How many tablets would the nurse administer to the patient for this dose?
3.
_________tab(s)
The prescriber orders Lanoxin 125 mcg IVP q8h times 3 doses. The
medication is labeled as follows:
31
LANOXIN
2 mL
0.5 mg in 2 mL
0.25 mg per mL
Store at 25o C (77o F)
PROTECT FROM LIGHT.
Lot #
Exp. 3/28
(digoxin) Injection
Rx only
How many mL should the nurse administer to the patient per dose? ______mL
4.
5.
The prescriber orders Trexall (methotrexate) 150 mg IV once every 14 days
to treat a cancer. The patient weighs 164 lbs.
a.
The safe dose for this drug is 2.5 mg/kg IV every 14 days.
What would be the safe dose for this patient?
_________________mg
b.
Is the dose ordered for this patient safe? (yes/no)
_______________
The prescriber orders Kefzol 500 mg IM now. The medication available is
labeled as follows:
NDC 0002-7014-01
Vial No. 7014
KEFZOL
cefazolin for
injection, USP
PHARMACY BULK PACKAGE
NOT FOR DIRECT INFUSION
10 g
Reconstitution: Add sterile water for
injection or 0.9% sodium chloride for
injection according to table below.
SHAKE WELL. FURTHER DILUTION IS
REQUIRED BEFORE IV USE.
Total amount diluent
Approx. Concentration
45 mL
96 mL
1 gram/ 5 mL
1 gram/10 mL
Prior to reconstitution: Protect from
light. After reconstitution: Use promptly
within 4 hours after initial entry.
a.
How much diluent should the nurse add for this situation?
_________mL
b.
How many mL should the nurse administer to the patient?
_________mL
32
6.
The prescriber orders an IV of D5 RL to run at 125 mL per hour. The drop
factor on the available tubing is 15 gtts/mL.
a. How many drops per minute should the IV be regulated for? ______gtt/min
(Only a whole number will be accepted.)
b.
If the nurse hangs a 1,000 mL bag at 11 AM, how much fluid will the
patient receive by 4 PM (1500 hours)?
___________mL
c. How much fluid will be left in the bag at 4 PM (1500 hours)?
d.
7.
________mL
At what time will the bag need to be changed?
________________
(Specify AM or PM or use military time.)
The prescriber orders Vancocin 1g in 250 mL of NS IVPB q12h.
a. How long will it take this IVPB to run in if the standard IVPB rate is used?
___________min
b.
The nurse choses tubing labeled 20 gtts/mL. How many gtts/min will
the nurse regulate the IVPB? (Only a whole number will be accepted.)
______gtts/min
If a volumetric pump is available, what rate should the nurse set the pump
for?
________mL/hr
33
8.
The prescriber orders NPH insulin 30 units and Regular Insulin 15 units to be
administered before breakfast daily.
Draw an arrow on the syringe scale below to indicate how much
insulin should be drawn into the syringe first. Label it with the
amount and type of insulin used.
a. draw up __________ units of
____________ insulin to this line
FIRST
b. add ________ units of
___________ insulin by pulling
plunger to this line
SECOND
c.
9.
Draw an arrow on the syringe scale above to indicate how far the
nurse should draw back on the plunger to add the second type of
insulin. Label this arrow with the name and amount of the second
type of insulin used.
The patient has a pre-prandial (before eating) blood sugar of 322. According
to the following sliding scale, how much regular insulin coverage should the
patient receive at this time?
Blood sugar
Under 150
150-199
200-249
250-299
300-349
350 or above
Dose of Humulin R insulin
No coverage
2 units
4 units
6 units
8 units
Call MD for instructions
Answer: ____________ units Humulin R insulin
34
1.
0.8 mL Using d/h x v, 8 mg/10 mg x 1 mL – 0.8 mL.
2.
1 tablet. Convert 0.4 g to mg by multiplying by 1,000 or move decimal point
over to the right by 3 spaces. 0.4 g = 400 mg. Each tablet is 400 mg.
3.
0.5 mL. 125 mcg may be converted into mg by dividing by 1,000 or moving
the decimal to the left 3 spaces. 125 mcg = 0.125 mg. Then use d/h x v =
0.125 mg/0.25 mg x 1 mL = 0.5 mL.
4.
a. Safe dose = 186.4 mg. Dose ordered is 150 mg.
b. Yes, dose is safe.
First, convert 164 lb to kg. 164 lb/2.2 lb/kg = 74.5454 kg, rounded. Next,
multiply wt in kg by dose per kg. 74.5454 kg x 2.5 mg/kg = 186.363636 mg,
which can be rounded to 186.4 mg as a final answer. The dose ordered is
150 mg, which is less than the maximum dose for this patient. Sometimes
medications do not come in the exact dose needed, so the prescriber gets as
close as possible without going over the maximum dose. The question did
not ask if the dose was therapeutic or not, only if it were safe. If it is less than
the maximum dose, it is safe.
5.
a. 45 mL of diluent should be added. 1 g/5 mL is the only choice that
would make a concentration small enough for an IM injection under 3 mL.
There is no calculation for this question. Just follow the directions.
b. 2.5 mL. 500 mg/1000 mg x 5 mL = 2.5 mL.
6.
a. 31 gtt/min. 125 mL/60 min x 15 gtt/mL = 31.25 rounded = 31 gtt/min.
b. 625 mL. 11 am to 4 pm = 5 hr. 125 mL/hr x 5 hr = 625 mL
c. 375 mL. 1000 mL in bag – 625 mL given to pt = 375 mL LIB at 4 pm.
d. 7 pm or 1900 hours. 1000 mL/ 125 mL/hr = 8 hr. If the bag will run
over 8 hours and was hung at 11 am, in 8 hrs it will be 7 pm or 1900
hours in military time.
7.
a.
b.
c.
150 minutes, or 2.5 hrs. The standard rate is 100 mL/hr. If no rate is
specified, the nurse may use this rate. 250 mL/100 mL/hr = 2.5 hr or
150 min (2.5 hr x 60 min/hr = 150 min)
33 gtt/min
250 mL/150 min x 20 gtt/mL = 33.333 or 33 gtt/min
100 ml/hr. That is the standard rate for an IVPB if not otherwise
ordered. Sometimes vancomycin is run more slowly if ordered.
8.
a.
b.
c.
Draw up 15 units of Regular insulin first.
Draw up 30 units of NPH second.
The total in the syringe should be 45 units.
9.
8 units Humulin R insulin.
Revised 06/29/2023