1. IV Drug Administration
Drug Calculations
November 2007

2. Drug Calculation Assessment
SECTION 1: Units & Equivalences
SECTION 2: Calculating dose as volume
SECTION 3: Drug Strengths & Stated Concentrations
SECTION 4: Duration of Infusion – Stated rate (dose per min) & Infusion rate (mL/hr)
SECTION 5: Infusion Rate Calculations

3. SECTION 1: Units & Equivalences
1 Kg =
1,000 g
1 g =
1,000 mg
1 mg =
1,000 micrograms
1 L =
1,000 mL

4. Converting from One Unit to Another
To convert from a larger unit to a smaller unit, multiply by 1000 or move the decimal point three places to the right
To convert from a smaller unit to a larger unit, divide by 1000 or move the decimal point three places to the left

5. Units & Equivalences Convert 0.25 mg into micrograms
Convert 600 micrograms to mg

6. Answers 0.25 × 1000 or move decimal point three places to the RIGHT
= 250 micrograms
600 ÷ 1000 or move the decimal point three places to the LEFT
= 0.6 mg

7. SECTION 2: Calculating Dose as Volume
What you WANT X what it is IN
What you have GOT
= the volume you want to administer

8. A patient is prescribed 200mg of Furosemide I. V
A patient is prescribed 200mg of Furosemide I.V. The ampoules available contain 250mg in 10mL. What volume containing the drug do you need to administer?
Furosemide
Time 
Dose
200mg
Route IV
Start Date
End Date
Other Time
Signature of Doctor
P.Rescriber
What it is IN
Furosemide 250mg/10mL
EMPHASISE TO STAFF IMPORTANCE OF GIVING IV FUROSEMIDE SLOWLY AND THAT THIS DOSE WILL NORMALLY BE ADDED TO A BAG, GIVEN AS AN INTERMITTENT INFUSION
WILL DISCUSS LATER ON SLIDE 11
What we WANT
What we have GOT

9. Answer What you WANT X what it is IN What you have GOT 200 mg
250 mg × 10 mL
= 8 mL

10. SECTION 3: Drug Strengths & Stated Concentrations
What you HAVE (mg)
CONCENTRATION (mg/mL)
= How much fluid is required (Volume)

11. Aciclovir CONCENTRATION
A patient is prescribed 250mg of Aciclovir I.V. Aciclovir has to be initially reconstituted with water for injection, then added to a bag of compatible infusion fluid, giving a final concentration of 5mg/mL. How much infusion fluid should be used dilute the reconstituted Aciclovir to achieve this final concentration?
Aciclovir
Time  
Dose
250mg
Route IV
Start Date
End Date 
Other Time
Signature of Doctor
Additional Comments
P.Rescriber
Final Concentration 5mg/mL
EMPHASISE THAT INFORMATION ON CONCENTRATION WOULD BE FOUND IN THE IV MONOGRAPHS
What we HAVE
CONCENTRATION

12. Answer What you HAVE (mg) CONCENTRATION (mg/mL) 250mg 5mg/mL = 50 mL
NOW WE ARE GOING TO DISCUSS DRUG STRENGTHS

13. A 1% (w/v) solution means that in every 100mL of solution you will find 1g of drug. Therefore, how many g of Glucose would there be in 500mL of 5% Glucose?
Glucose 5%
500ml

14. Answer
A 1% (w/v) solution means that in every 100mL of solution you will find 1g of drug.
100mL = 1g
Therefore a 5% w/v must mean that
100mL = 5g
Multiply each side by 5
500mL = 25g
REMIND STAFF THAT WE WANT 500mL

15. 1:10,000 strength means that in every 10,000ml of solution you will find 1g of Adrenaline. Therefore, how many mg of Adrenaline would there be in 10mL of 1:10,000 Adrenaline?
THIS RATIO IS ONLY RELEVANT TO ADRENALINE

16. Answer 1:10,000 means that 1g of adrenaline is dissolved in 10,000mL.
1g = 10,000mL
1000mg = 10,000mL
Divide both sides by 1000
1mg = 10mL
POSSIBLY DRAW THIS ON THE FLIPCHART

17. SECTION 4: Duration of Infusion Stated rate (dose per min) Infusion rate (mL/hr)
Dose (mg) = Time
Rate (mg/min)

18. Furosemide must be administered at a rate no faster than 4mg/minute
Furosemide must be administered at a rate no faster than 4mg/minute. How many minutes would it take to give 200mg of this drug?
Furosemide
Time 
Dose
200mg
Route IV
Start Date
End Date
Other Time
Signature of Doctor
Additional Comments
P.Rescriber
Rate of 4mg/minute
DOSE(mg)
Furosemide 250mg/10mL
INFORMATION ON RATE OF INFUSION WILL BE FOUND IN THE IV MONOGRAPHS
Rate
(mg/min)

19. Answer
Dose (mg) = Time
Rate (mg/min)
200mg
4mg/min
= 50 minutes

20. Infusion rate – mL/hr Volume (mL) = Rate (mL/min) Time (Min)
X 60 = Rate (mL/Hr)
* Tip if rate is in hours omit “X 60”

21. Omeprazole (Losec ®) 40mg is diluted in 100mL of compatible infusion fluid. This infusion has to be given over 20 minutes. What rate should you set the infusion pump at, in ml/hr, to deliver this dose?
Omeprazole 40mg/100mL

22. Answer Volume (mL) = Time (mL/hr) x 60 Rate (hr) 100ml 20 mins x 60

23. Acetylcysteine (Parvolex ®) 7
Acetylcysteine (Parvolex ®) 7.5g is diluted in 1000mL of compatible infusion fluid. This infusion has to be given over 16 hours. What rate should you set the infusion pump at, in ml/hr, to deliver this dose?
Acetylcysteine 7.5g/1000mL

24. Answer
Dose (mL) = Time (mL/hr)
Rate (hr)
1000 16
= 62.5 mL/hr

25. SECTION 5: Infusion Rate Calculations
What you WANT x 60 (60 mins per hr)
What you have GOT X what it is IN
= the volume you want to administer

26. Glyceryl Trinitrate 50mg/50mL
You are required to give a patient Glyceryl Trinitrate as a continuous I.V infusion at 25 micrograms/minute. You have prepared a 50mg in 50mL infusion. What rate should you set the infusion pump at, in ml/hr, to deliver this dose?
What we have GOT
Glyceryl Trinitrate
Time
Dose
25 micrograms/
minute
Route IV
Start Date
End Date
Other Time
Signature of Doctor
Additional Comments
P.Rescriber
Continuous Infusion
What we WANT
Glyceryl Trinitrate 50mg/50mL
60 mins per hr
What its IN

27. Answer What you WANT x 60 (60 mins per hr)
What you have GOT X what it is IN
25 micrograms x 60 = 1500 micrograms/hr
1500 ÷ 1000
= 1.5 mg
1.5 mg x 50mL
50 mg
= 1.5 mL/hr

28. Any Questions?
Assessment time……