2. DRUG DOSAGE CALCULATIONS
Drug dosage calculations are required when
the amount of medication ordered (or
desired) is different from what is available on
hand for the nurse to administer.
3.
4. s
DRUG DOSAGE CALCULATIONS
D (Desired) = The dosage that the physician ordered
H (HAND) S (STOCK) = The dosage strength as stated on the medication label
Q (Quantity) = The volume that the dosage strength is available in, such as tablets,
capsules, or ml
5. EXAMPLE NO. 1
Toprol XL, 50 mg PO, is ordered. Toprol XL is
available as 100 mg per tablets. How many
tablets would the nurse administer?
11. EXAMPLE 4
Furosemide is available as 40 mg in 1
mL. 10 mg is ordered to be
administered through an IV. What
amount of furosemide should the nurse
administer?
14. DOSAGE CALCULATIONS BASED ON BODY
WEIGHT
• Dosage calculations based on body weight are
required when the dosage ordered and administered is
dependent on the weight of the patient.
• For example, many pediatric drugs are ordered and
given per weight (usually in kg).
• Dosage calculations based on body weight are
calculated in two main stages.
16. EXAMPLE 1
Medrol 4 mg/kg is ordered for a child
weighing 64.8 lb. Medrol is available as
500 mg/4mL. How many milliliters of
medication must the nurse administer?
19. EXAMPLE 2
A doctor prescribes 250 mg of Ceftin to be
taken by a 20.5 lb infant every 8 hours. The
medication label indicates that 75-150 mg/kg
per day is the desired dosage range. Is this
doctor's order within the desired range?
24. CALCULATION OF INTRAVENOUS DRIP
RATES
• In these types of calculations, for a given volume, time period,
and drop factor (gtts/mL), the required IV flow rate in drops per
minute (gtts/min) is calculated.
• Note: Since a fraction of a drop is not possible to give to a
patient, it is usual to round the answers to the nearest whole
number.
• Macrodrops = 15 gtts/min (adult)
• Microdrops = 60 ugtts/min (pedia)
26. EXAMPLE 1
Calculate the IV flow rate for 250 mL of
0.5% dextrose to be administered over
180 minutes. The infusion set has drop
factor of 30 gtts/mL.
28. EXAMPLE 2
The infusion set is adjusted for a drop
factor of 15 gtts/mL. Calculate the IV
flow rate if 1500mL IV saline is ordered
to be infused over 12 hours.
30. CALCULATION OF FLOW RATE FOR AN
INFUSION PUMP
• Infusion pumps do not have a calibrated drop factor.
The flow rate depends on the volume of fluid ordered
and the time of infusion.
31. EXAMPLE 1
1200 mL D5W IV is ordered to infuse
in 10 hours by infusion pump.
Calculate the flow rate in milliliters
per hour.
36. EXERCISE NO. 1
The physician orders
Ampicillin 1g q6h
orally (PO). How
many capsules would
you administer q6h?
37. EXERCISE NO. 2
The physician orders
Lanoxin 0.75 mg IM
every day. How much
Lanoxin would you
administer IM ?
38. EXERCISE NO. 3
The physician orders
Cefazolin 400mg IV
q12 hrs. ANST, in 5ml
dilution.. How much
drug would you
administer?
39. EXERCISE NO. 4
• The physician ordered for
a 10 years old child,
Paracetamol 200mg IV
PRN for fever. How much
drug would you
administer?
40. EXERCISE NO. 5
• The physician ordered
Gentamicin 10mg/kg to a child
whose weight is 15 lbs. how
much drug will the nurse
administer?
41. EXERCISE NO. 6
•The physician ordered
Benzylpenicillin 1.2 million
units in 10 ml dilution. How
much drug is needed?
42. EXERCISE NO. 7
• The order is D5LR 1.5 L to run
for 10 hours. Drop factor 20
gtts/min. Compute for the
following:
• Cc/hr
• Gtt/min
43. EXERCISE NO. 8
• A patient has 350 mL of Plain 0.9 NaCl
solution as IV infusion regulated at 20
drops per minute. Drop factor 10 was
used for the patient’s macrodrip set.
Considering the IV fluid level of the
patient, for how many minutes will it
run?
44. EXERCISE NO. 9
• you receive the IV fluid of patient
0.9 NaCl 800 ml for 10 hours with a
drop factor of 15gtts/min. compute
for the ff:
• CC/hr
• Gtts/min
• Microdrops/min
