Determination of Isotonicity by Sodium Chloride
Session 13: Determination of Isotonicity by Sodium Chloride
Equivalent Method
Total Session Time: 120 minutes + 6 hours of Practices
Prerequisites
Learning Tasks
By the end of this session students are expected to be able to:
Resources Needed:
SESSION OVERVIEW
Activity/
Step Time Content
Method
1 05 Minutes Presentation Introduction, Learning Tasks
45 Minutes Presentation Introduction to Sodium Chloride Equivalent
2 Method
Brainstorming
60 Minutes Presentation Determining the Isotonicity by Sodium Chloride
3 Method
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: Sodium Chloride Equivalent Method (45 minutes)
effect (based on number of particles) as 1g of the drug sample calculation
solution x sodium chloride equivalent of medicament)
required percentage of sodium chloride and then divide this by the sodium chloride equivalent of
the chosen adjusting substance
o Calculate the percentage of anhydrous dextrose required to render a 1% solution of ephedrine
hydrochloride iso – osmotic with body fluid
o Sodium chloride equivalent
0.1
STEP 3: Determining the Isotonicity by Sodium Chloride Equivalent Method (60
minutes)
Rx
Atropine Sulfate 2%
NaCl qs
M.ft. isotonic solution
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2. Calculate the contribution of atropine sulfate to the NaCl equivalent
3. Determine the amount of NaCl to add to make the solution isotonic by subtracting (2) from (1)
Other substances may be used, in addition to or in place of NaCl, to render solutions isotonic.
This is done by taking the process one step further and calculating the amount of the
substance that is equivalent to the amount of NaCl calculated in step 3.
For example, boric acid is often used to adjust isotonicity in ophthalmic solutions because of
its buffering and anti-infective properties. If E for boric acid is 0.50, then the amount of boric
acid needed to replace the NaCl in step 3 can be calculated:
Or
or, more simply:
solution isotonic
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To determine amount of ingredients required making isotonic solution
Activity: Small Group Discussion (20 minutes)
DIVIDE students in small manageable groups
ASK students to discuss in groups on the following questions
morphine sulphate 1%, hyoscine hydrobromide 0.04% and sodium metabisulphate 0.1%
iso – osmotic with blood plasma
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
STEP 4: Key Points (5 minutes)
effect (based on number of particles) as 1g of the drug sample calculation
solution x sodium chloride equivalent of medicament)
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required percentage of sodium chloride and then divide this by the sodium chloride equivalent of
the chosen adjusting substance
STEP 5: Evaluation (5 minutes)
STEP 6: Take Home Assignment (15 minutes)
Activity: Take home Assignment (15 minutes)
ASK each individual student to do the following assignment
serum and tears
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.
& Sons, Inc
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