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IV Drug Administration Drug Calculations November 2007.

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Presentation on theme: "IV Drug Administration Drug Calculations November 2007."— Presentation transcript:

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 What we WANT Furosemide 250mg/10mL Furosemide Time Dose 200mg Route IV Start Date End Date Other Time Signature of Doctor P.Rescriber What we have GOT What it is IN 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?

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 Time Dose 250mg Route IV Start Date End Date Other Time Signature of Doctor Additional Comments P.Rescriber Final Concentration 5mg/mL 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? What we HAVE CONCENTRATION

12 Answer What you HAVE (mg) CONCENTRATION (mg/mL) 250mg 5mg/mL = 50 mL

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

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?

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 mg = 10mL

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

18 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 Furosemide 250mg/10mL Rate (mg/min) DOSE (mg)

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 40mg/100mL 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?

22 Answer Volume (mL) = Time (mL/hr) x 60 Rate (hr) 100ml 20 mins x 60 = 300mL/hr

23 Acetylcysteine 7.5g/1000mL 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?

24 Answer Dose (mL) = Time (mL/hr) Rate (hr) = 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 Time Dose 25 micrograms/ minute Route IV Start Date End Date Other Time Signature of Doctor Additional Comments P.Rescriber Continuous Infusion 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 WANT Glyceryl Trinitrate 50mg/50mL What we have GOT What its IN 60 mins per hr

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……


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