Hospital Pharmacy Calculations-MSQ Foundation

3. Hospital Pharmacy Dose
Calculations

4. Dimensional
Analysis
Ratio Proportion Formula
Method
Calculation of Medication Doses

5. How many tablets should
you prescribe if a patient
needs 4 tablets of drug
twice daily for six day
Four Tablets twice a day
means Eight Tablets
daily. Total 48 Tablets

6. A patient enters your pharmacy asking for his cough medicine. His doctor
prescribed him 15 Ml of medicine four times a day for 7 days. What number of
doses is needed and what minimum volume of cough medicine needs to be
dispensed
Doses delivered every 5 ml
15 ml means three spoonful
4 times a day dose for seven
days means 28 doses
28 X 15 mL = 420 mL

7. A patient has been prescribed 9 mg of Drug A twice-daily for 5/7. She is also
prescribed 7 mg once-daily (of the same drug) for the remaining 2/7. Drug A
is only available in 2 mg and 5 mg tablets. How many tablets of each
strength should be prescribed to the patient?
9 mg two times daily means
18 mg
18 mg for 5 days = 90 mg
14 mg required for last two
days
Total 104 mg of drug
Two 5 mg and four 2 mg Tab
Daily
One 5 mg and One 2 mg
tablets last two days

8. Adrenaline is available as Injection of 100 micrograms/mL. A patiend needs
an intramuscular injection of 0.5 mg. How may mL of injection are needed to
supply the required dose.
Units needs to be checked
0.5 mg = 500 micrograms
Adrenaline is available as an injection of 100 micrograms/mL
5 mL is our dose

9. The recommended dose of fluconazole for mucosal candidiasis in children in
3 mg/kg daily. Calculate the dose needed for a child (3-Years old). Suggest an
appropriate formulation
As per BNF, child is person
under age 12
14 kg is ideal weight for 3 years
old child as per BNF
42 mg of Fluconazole
Available formulations
50 mg, 150 mg, 200 mg capsules
50mg/5mL and 200 mg/5mL suspensions
50 mg/5mL means 1 mg has 0.1 mL
42 mg means 42 X 0.1 mL = 4.2 mL

10. Drug A needs to be dosed at 15 mg/kg daily in two divided doses. Calculate
the dose for a 6-month old child and the volume of paediatric injection to be
dispensed. Drug A is available in a formulation of 50 mg/mL
Ideal body weight of a 6-month
child is 7.6 kg
If 15 mg per kg then 114 mg for
7.6 kg
50 mg in 1 mL then 0.02 mL
contain 1 mg
0.02 mL X 114 mg = 2.28 mL
Dose to be given in two divided doses
1.14 mL each dose

11. What oral dose of methotrexate is suitable for a 5 year old child weighing 18
kg? The oral Dose is 15 mg/m2 weekly.
Ideal body surface area for a 5-
year old child is 0.74 m2
15 mg in 1 m2
11.1 mg

12. Formulation A contains 9.25 mg of Vitamin A (as retinyl acetate) and 400 IU
of ergocalciferol. Formulation Y contains 2,240 IU of Vitamin A and 10
micrograms of vitamin D. Which formulation contains the greatest vitamin
concentration?
Wait…. Unites are not same
1 IU = 0.344 micrograms
9.25 mg = 9250 microgram
26890 IU of Vitamin A in Formulation A
Apply for ergocalciferol…

13. Formula for Calculations
What you want/what you have X Quantity it comes in/1 = Required Answer

14. A patient requires 4 mg of Morphine IVI. Morphine is available as 10 mg/ml.
How many mls will you draw up?
0.4 mls

15. Gentamicin 360 mg is prescribed. Gentamicin is available as 80 mg/2ml. How
many mls will you draw up?
9 mls

16. Haloperidol 3 mg IVI is charted. Haloperidol is available as 5 mg/ml. How
many mls is required?
0.66 mls

17. Frusemide 70 mg IVI is charted. Stock dose is 20 mg/ml. How may ml would
you give?
3.5 mls

18. Formula for Infusion calculation:
Total Fluid in mls/(Total Hours X 60 mints) X Giving set calibration/1 =
required drops per minute

19. A patient is prescribed Sodium Chloride 1000 ml to be infused over a period
of 8 hours. A standard giving set is being used. Calculate drops per minute.
(hint: Standard set is 20 drops in 1 ml
41.66 drops/minute

20. Your patient is prescribed a 1000 ml infusion of sodium chloride 0.9 % to be
given over 6 hours. Using buretrol giving set, calculate the drops per minues,
166.6 drops per minutes