Reconstitution of Solutions

Chapter 12

2

Parts of Solutions

3

Reconstitution Drug

4

Parenteral Solution from a Solid Solute

Solvent or diluent4.8 mL sterile water

Solid soluteZithromax 500 mg

5 mL reconstituted solutionZithromax 100 mg per mL

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Reconstitution Label for Zithromax

1/10/xx, 0800, reconstituted as 100 mg per mL

Expires 1/17/xx, 0800.

Keep refrigerated. G.D.P.

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Parenteral Solution Reconstitution Procedure

Order: Kefzol 225 mg IM every 6 hours

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Parenteral Reconstitution Procedure

Inject 2 mL air into sterile water

diluent vial

Withdraw 2 mL

sterile water

Add 2 mL sterile water to Kefzol 500 mg powder

Make Kefzol 500 mg in 2.2 mL

reconstituted solution for Kefzol 225

mg/mL

Withdraw 1 mL Kefzol solution for dosage of

225 mg

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Multiple-StrengthReconstitution Drug

9

Different IM and IVReconstitution Instructions

10

Reconstitution Drug Order

• Order: Solu-Medrol 200 mg IV every 6 hours

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Reconstitution Drug Order • Supply:

– 500 mg vial of powdered Solu-Medrol for IM or IV injection

– Directions on left side of label

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Reconstitution Drug Order • Each 8 mL contains

– “Reconstitute with 8 mL Bacteriostatic Water for Injection with Benzyl Alcohol

– Methylprednisolone sodium succinate equivalent to 500 mg methylprednisolone (62.5 mg per mL)”

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Reconstitution Dosage Calculation

• What do we know?– First, to fill the order, how much and what type

of diluent must you add? – Directions state to add 8 mL of bacteriostatic

water for injection with benzyl alcohol.

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Reconstitution Dosage Calculation

• What do we know?– Second, what is supply dosage of

reconstituted Solu-Medrol? – When adding 8 mL of diluent, the supply

dosage is 62.5 mg per mL

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Reconstitution Dosage Calculation

• What do we know?– Third, what is resulting total volume of this

reconstituted solution? – Total volume is 8 mL – You know this because

• 62.5 mg per mL × 8 mL = 500 mg

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Reconstitution Dosage Calculation

• What do we know?– Finally, how many full doses of Solu-Medrol

are available in this vial? – Vial contains 500 mg and order is for 200 mg – There are two full doses in the vial – Reconstitution label is needed

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Reconstitution Dosage Calculation

• Now you have a vial of 500 mg of Solu-Medrol – Add 8 mL of diluent

• Final yield of the solution is 62.5 mg per mL, your supply dosage.

• Calculate one dose

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Reconstitution Dosage Calculation • Step 1. Convert

– No conversion is necessary– Order: Solu-Medrol 200 mg IV every 6 hours– Supply: 62.5 mg per mL

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Reconstitution Dosage Calculation

• Step 2. Think– You want to give more than 1 mL– You want to give more than three times 1 mL

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Reconstitution Dosage Calculation

• Step 3. Calculate

62.5 mg

1 mL

200 mg

X

62. 5 X

200

X = 3.2 mL

• Given intravenously every 6 hours

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Solution Strength• A fraction expresses strength of a solution

made from a liquid concentrate:– Numerator is number of parts of solute– Denominator is number of parts of solution– Difference between denominator (final

solution) and numerator (parts of solute) is number of parts of solvent

22

Solution Strength• Example: strength nutritional formula

– 1 part concentrate– 3 parts of total solution– 3 - 1 = 2 parts solvent (water)

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23

Calculating Solutions• To prepare solutions:

– Apply ratio-proportion to find amount

– Quantity of desired solution • Amount of liquid solute = Amount of solvent

Ratio for desired solution strength = Amount of solute

Quantity of desired solution

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Solution Calculation• Example:

– A physician orders a patient’s wound irrigated with strength hydrogen peroxide and normal saline solution every 4 hours while awake.

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25

Solution Calculation• 60 mL per irrigation for 3 irrigations during

your 12 hour shift– Prepare 60 mL × 3 irrigations = 180 mL total

solution

• How much stock hydrogen peroxide and normal saline will you need?

26

Solution Calculation

• Step 1. Convert– No conversion is necessary

27

Solution Calculation• Step 2. Think

– You want to make strength• 2 parts solute (concentrated hydrogen peroxide) to

3 total parts solution

• Amount of solvent is 3 – 2 = 1 part saline

• For 180 mL of solution, you will need of it as solute (120 mL) and of it as solvent (60 mL)

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Solution Calculation• Step 3. Calculate

2

3

X mL

180 mL(solute)

(solution)

3X 360

3X

3

360

3X 120 mL of solute (hydrogen peroxide)