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# IV Drug Administration - PowerPoint PPT Presentation

IV Drug Administration. Drug Calculations. November 2007. 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)

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Presentation Transcript

Drug Calculations

November 2007

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
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
Units & Equivalences

Convert 0.25 mg into micrograms

Convert 600 micrograms to mg

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

SECTION 2: Calculating Dose as Volume

What you WANT X what it is IN

What you have GOT

= the volume you want to administer

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?

What it isIN

Furosemide 250mg/10mL

What weWANT

What we haveGOT

What you WANT X what it is IN

What you have GOT

200 mg

250 mg × 10 mL

= 8 mL

SECTION 3: Drug Strengths & Stated Concentrations

What you HAVE (mg)

CONCENTRATION (mg/mL)

= How much fluid is required (Volume)

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 weHAVE

CONCENTRATION

What you HAVE (mg)

CONCENTRATION (mg/mL)

250mg

5mg/mL

= 50 mL

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

• 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

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?

• 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

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)

Furosemide must be administered at a rate no faster than 4mg/minute. How many minutes would it take to give 200mg of this drug?

DOSE(mg)

Furosemide 250mg/10mL

Rate

(mg/min)

Dose (mg) = Time

Rate (mg/min)

200mg

4mg/min

= 50 minutes

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”

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

Volume (mL) = Time (mL/hr) x 60

Rate (hr)

100ml

20 mins x 60

= 300mL/hr

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

Dose (mL) = Time (mL/hr)

Rate (hr)

1000

16

= 62.5 mL/hr

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

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 haveGOT

What weWANT

Glyceryl Trinitrate 50mg/50mL

60 mins per hr

What itsIN

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

Any Questions?

Assessment time……