NTA Level 5 • Semester 2 • PST05208

Calculations Involving Intravenous Admixture

Pharmaceutics Theory and Compounding • Source Session/Topic 20

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Session 20: Calculations Involving Intravenous Admixture

Total Session Time: 120minutes + 6 hours of Practices

Prerequisites

• None

Learning Tasks

By the end of this session students are expected to be able to:

• Give overview of calculations involving intravenous admixture

• Perform calculations Involving of intravenous admixture

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board, chalk and whiteboard markers

• LCD projector and computer

SESSION OVERVIEW

Activity/

Step Time Content

Method

1 05 minutes Presentation Introduction, Learning Tasks

45minutes Introduction to calculations involving intravenous

2 Presentation admixture

60 minutes Presentation Performing Calculations Involving Intravenous

3 Admixture

Demonstration

4 05 minutes Presentation Key Points

5 05 minutes Presentation Evaluation

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SESSION CONTENTS

STEP1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Introduction to Calculations Involving Intravenous Admixture (45

Minutes)

• The preparation of intravenous admixtures involves the addition of one or more drugs to large

volume sterile fluid such as sodium chloride injection, dextrose injection, lactated ringer‟s

injection and others.

• The additives are generally in the form of small volume sterile solutions packed in ampules, vials,

small – volume minibags for use as piggybacks, or sterile solids, some requiring constitution with

a sterile solvent before transfer

• Although a wide variety of drugs and drug combinations are used in preparing dilute infusions for

intravenous therapy, some of the more common additives include electrolytes, antibiotics,

vitamins, trace minerals, heparin, and, in some instances, insulin

• In any properly administered intravenous admixture programme, all basic fluids(large volume

solutions), additives (already in solution or extemporaneous constituted), and calculations must be

carefully checked against the medication

• Patient care facilities often adopt standard concentrations of intravenous solutions of commonly

used drugs to provide uniformity within the institution

• Common examples are dopamine 400mg in 250mL of D5W, insulin 25 units in250mL of NS, and

nitroglycerin 50mg in 250mL D5W.

• In preparing these standard concentrations, the pharmacist withdraws the determined volume

From an ampule or vial containing the concentrated drug solution and transfers it to the specified

volume of D5W, NS, or other intravenous fluid.

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STEP 3: Performing Calculations Involving Intravenous Admixture (60minutes)

Activity: Small Group Discussion ( 30 minutes)

DIVIDE students in small manageable groups

ASK students to discuss in groups on the following questions

• A medication order for a patient weighing 154lb. calls for 0.25mg of amphotericin B per

kilogram of body weight to be added to 500mL of 5% dextrose injection. If amphotericin

B is to be obtained from a constituted injection that contains 50mg/10mL, how many

milliliters should be added to the dextrose injection?

REFER Students to Pharmaceutical Calculation. 13th Edition by HOWARD C.

ANSEL: Chapter 11, for reference

ALLOW students to discuss for 20 minutes

ALLOW each groups to present for 5 minutes

CLARIFY and SUMMARIZE by using the contents below

1kg == 2.2 lb.

154(lb.) = 70

2.2(lb.)

0.25mg x 70 = 17.5mg

Constituted solution contains 50 mg/ 10mL

50 (mg) == 10 (mL) x = 3.5mL

17.5(mg) x (mL)

OR, solving by dimensional analysis:

154 lb. x1kg x 0.25mg x 10mL = 3.5mL

2.2lb 1kg 50mg

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STEP 4: Key Points (5 minutes)

• The preparation of intravenous admixtures involves the addition of one or more drugs to large

volume sterile fluid such as sodium chloride injection, dextrose injection, lactated ringer‟s

injection and others.

• The additives are generally in the form of small volume sterile solutions packed in ampules, vials,

small – volume minibags for use as piggybacks, or sterile solids, some requiring constitution with

a sterile solvent before transfer

STEP 5: Evaluation (5 minutes)

• What are the procedures for preparation of intravenous admixtures?

STEP 6: Take Home Assignment (15 minutes)

Activity: Take home Assignment (15 minutes)

ASK each individual student to do the following assignment

• An intravenous infusion is to contain 15mEq of potassium ion and 20mEq of sodium

ion in 500mL of 5%. Using potassium chloride injection containing 6g/30mL and

0.9% sodium chloride injection, how many milliliters of each should be used to supply

the required ions?

ALLOCATE time for students to do the assignment and submit

REFER students to recommended references

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References

Ansel, H. C &Stocklosa, M. J. (2001). Pharmaceutical Calculations (11th ed.). Philadelphia, United

States: LIPPINCOTT WILLIAMS & WILKINS

Ansel, H. C (2010) Pharmaceutical Calculations (13rd ed.). Philadelphia, United States:

LIPPINCOTT WILLIAMS & WILKINS

Senya, S. S, Mwasha, C.Y, Muyinga, A. M, Amiri,R. I. and Mauga E.A.S.K. (2011) Tanzania

Pharmaceutical Handbook (2nd ed.). Dar eS Salaam, Tanzania: School of Pharmaceutical

Sciences.

Zatz, J.L and Teixeira, M.G. (2005). Pharmaceutical Calculation (4th ed.). New Jersey: John Wiley

& Sons, Inc

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