Pharmacy Jun Tomeldan Calculations

1. Calculations

2. Calculations
Volume/Time
Y (Flow Rate in mL/hr) = Volume (mL)/ Time (hr)
Infuse 250 mL over the next 120 minutes by infusion pump.
Volume (mL) Time (hr) = Y (Flow Rate in mL/hr)
Convert 120 minutes to hours.
min → hr ( ÷ by 60 )
120 min ÷ 60 = 2 hr
250 mL 2 hr = 125 mL/hr

3. Drop/volume
Formula:
x (Flow Rate in gtts/min)= Volume (mL)/Time (min)
Calculate the IV flow rate for 1200 mL of NS to be infused in 6
hours. The infusion set is calibrated for a drop factor of 15
gtts/mL.
Convert 6 hours to minutes.
min ← hr ( x by 60 )
6 hr x 60 = 360 min
1200 mL 360 min x 15 gtts/mL = 50 gtts/min

4. Fluid Maintenance
Weight Range Required Daily Fluid
0-10 kg 100 mL per kg
10-20 kg 1,000 mL + 50 mL per each kg above 10 kg
20-70 kg 1,500 mL + 20 mL per each kg above 20 kg
Over 70 kg 2,500 mL (adult requirement)
An infant weighs 4 kg. What is the required amount of fluid per day in mL
4 kg x 100 mL/kg = 400 mL

5. Fluid Maintenance
An infant weighs 30.8 lb. What is the required IV flow
rate in mL/hr to maintain proper fluid levels?
Convert 30.8 lb to kg. lb → kg ( ÷ by 2.2 )
30.8 lb ÷ 2.2 = 14 kg
14 kg - 10 kg = 4 kg (There are 4 kg over 10 kg).
1,000 mL + (50 mL/kg x 4 kg) = 1,200 mL/day

6. Dosage By Weight
Formula:
x= (Weight in Kg) (Dosage Per Kg)
A doctor orders 200 mg of Ceftriaxone to be taken by a 15.4 lb infant
every 8 hours. The medication label shows that 75-150 mg/kg per day
is the appropriate dosage range. Is this doctor's order within the
desired range?
Convert 15.4 lb to kg. lb → kg ( ÷ by 2.2 )
15.4 lb ÷ 2.2 = 7 kg

7. Dosage By Weight
x= (Weight in Kg) (Dosage Per Kg)
7 kg * 75 mg/kg = 525 mg
(Minimum Desired Dosage) 7 kg * 150 mg/kg = 1,050 mg
(Maximum Desired Dosage) 24 hours in one day and the
medication is ordered every 8 hours. 24 hrs / 8 hrs = 3 times
per day doctor ordered medication
200 x 3 = 600 mg ordered per day
600 mg is within the desired range of 525-1,050 mg

8. BSA-Body Surface Area
Formula:
BSA= wt (lbs) x ht (in)
3131
A 14 year old boy is 5'2" and he weights 110 lbs. The Doctor’s
order is to take 5mg/Kg of drug "A" daily. What will his dose be?
a. 1200mg
b. 1250mg
c. 150mg
d. 250mg

9. Oncology Calculations
1. There is an order for Velcade (bortezomib) to be
given subcutaneously. The dose to be given is 2.6
mg. Velcade comes as a 3.5 mg powder for
reconstitution. The concentration of Velcade when
given subcutaneously is to be 2.5 mg/ml.
a. What volume of normal saline do you need to
add to the 3.5 mg vial of powder to end up with
final concentration of 2.5 mg/ml?
b. What volume of the 2.5 mg/ml solution do you
need to supply the required dose of 2.6 mg?

10. Oncology Calculations
1. Stock: Velcade 3.5mg
Order: 2.6mg
Concentration: 2.5mg/ml
a. 3.5 mg = 2.5 mg
X ml
2.5 X = 3.5
2.5 X 2.5
= 1.4ml of normal saline

11. Oncology Calculations
b. Concentration: 2.5mg/ml
Order: 2.6mg
Solution:
2.5 mg = 2.6mg
ml X
2.5x = 2.6
2.5x 2.5
= 1.04 ml

12. Oncology Calculations
2. A patient is scheduled to receive paclitaxel 290 mg . Paclitaxel
is supplied in a concentration of 6 mg/ml. How many mls will
be required to provide the 290 mg dose?
Order: 290mg
Concentration: 6mg/ml
Solution:
6 mg = 290mg
ml X
6x = 290
6 6
x = 290
6
x = 48.3 ml

13. Oncology Calculations
3. You are about to prepare a Mitomyicn ophthalmic
syringe injection. The Mitomycin stock dose is 5mg
a vial. The desired concentration for the ophthalmic
injection is 0.4mg/ml. How many milliliters of normal
saline should be used to reconstitute a 5mg vial?

14. Oncology Calculations
Desired Amount: 0.4mg/ml
Stock: 5mg
Solution:
0.4 mg = 5mg
ml X
0.4x = 5
0.4 0.4
x = 5
0.4
x = 12.5 ml

15. Oncology Calculations
4. The doctor wrote an order for Zometa (zoledronic acid )3.5mg.
The vial of Zometa(Zoledronic acid) comes in 4mg per 5ml.
How many milliliters should be drawn to complete the order?
Desired Amount: 0.4mg/ml
Stock: 5mg
Solution: 4 mg = 3.5mg
5ml x
17.5x = 4x
4 4
x = 17.5
4
x = 4.4 ml

16. Oncology Calculations
6. Order: Gemzar (gemcitabine) 1940 mg in NS
100ml.
Stock: 38mg/ml
What is the right dose?
38 mg = 1940 mg
ml x
1940 = 38x
38 38
x = 1940
38
x = 39.2 ml

17. Oncology Calculations
7. Ferrlecit (sodium ferric gluconate) has been ordered for
125mg. The supply available is 62.5 mg elemental iron/5ml.
How many milliliters are needed to fill the order?
Concentration: 62.5 mg/5ml
Order: 125mg
Solution:
62.5 mg = 125 mg
5ml x
625 = 62.5x
62.5 62.5
x = 625
62.5
x = 10 ml

18. Oncology Calculations
8. Alimta(pemetrexed) is for lung cancer. An order was placed for 456mg.
The vial comes in 100mg. To reconstitute, add 4.2ml 0.9% sodium
chloride to make a solution 25mg/ml. How many milliliters are needed?
Concentration: 25 mg/ml
Order: 456mg
Solution:
25 mg = 456 mg
ml x
25x = 456
25 25
x = 456
25
x = 18.24 ml

19. Oncology Calculations
9. An order is written for Decadron (dexamethasone) 20mg. The stock vial
comes in a concentration of 4mg/ml. Calculate the dose.
Order: 20mg
Concentration: 4mg/ml
Solution:
4 mg = 20 mg
ml x
4x = 20
4 4
x = 20
4
x = 4 ml

20. Calculations
10. Rituxan (rituximab) dose is 375mg/m². The
BSA(body surface area) of the patient is 2.4m².
Calculate the actual dose for the patient.
BSA= 2.4m²
Dose= 375mg/m²
Solution:
375 mg = X
m² 2.4m²
X = 900mg

21. Calculations
11. Patient’s height is 69 inches and weighs 250
pounds. Calculate his BSA.
Ht = 69 inches Wt = 250lbs.
Solution:
BSA = √ wt x ht
3131
= √ 250 x 69
3131
= √ 17250
3131
= √ 5.51
= 2.3 m²

22. Calculations
12. Calculate the patient’s
BSA.
Wt: 67inches
Ht: 95kg
Solution:
95kg. = .454kg
x lb = 1lb
.454 x = 95
.454 .454
x = 95
.454
x = 209.25 lbs
BSA = √ wt x ht
3131
= √ 72 x209.25
3131
= √ 15066
3131
= √ 4.8
= 2.19 m²

23. Calculations
13. The maximum dose for
Trisenox (arsenic trioxide)this
drug is 0.15mg/kg/day. If the
patient weighs 190 lbs. What
is his dose for five days?
Solution:
190 lbs = 2.2 lbs
x kg 1 kg
2.2 x = 190
2.2 2.2
x = 190
2.2
x = 86.36 kg
0.15 mg = x mg
kg 86.36
x kg = 0.15 x 86.36
x = 12. 954 mg or 13mg/day
13mg = x mg
day 5 days
x = 65mg