1. Prelab 7

2. Alligation Problems
Liquid Paraffin emulsion

3. ALLIGATION p.45

4. Alligation Medial
Used to calculate the “Average Percentage Strength” of mixture of two or more substances whose quantities and concentrations are known.

5. What is the percentage of alcohol in a lotion containing 1500ml
What is the percentage of alcohol in a lotion containing 1500ml. of witch hazel (14% alcohol), 2000ml. of glycerin, and 5000 ml. of 50% alcohol?

6. Alligation Alternate Percent desired Percent given Parts required
Used to calculate the number of parts of two or more components of a given strength when that should be used to prepare a mixture of desired strength.
Percent desired
Percent given
Parts required

7. a y c b x Number of parts of minus gives gives minus

8. Example
In what proportion should alcohols of 95% and 50% strengths be mixed to make 270 ml 70% alcohol? 95 20
Number of parts of
minus
gives 70
minus
gives 50 25
Number of parts of

9. 120
150
270
 Mix 120 ml of 95% alcohol with 150 ml of 50% alcohol to produce 270 ml of 70% alcohol.

10. In what proportion should 20% benzocaine ointment be mixed with ointment base to produce a 2.5% benzocaine ointment?
2.5
20%
zero%
2.5%
17.5

11. 100% 15% 10% 5 85 100% : 10% Parts 5 : 85 grams x : 3400g x= 200 g
How many grams of zinc oxide should be added to 3400 g. of a 10% zinc oxide ointment to prepare a product containing 15% of zinc oxide?
100%
10%
15% 5 85
100% : %
Parts :
grams x : g
x= 200 g

12. A hospital pharmacist wants to use three lots of ichthammol ointmentcontaining respectively 50%. 20%, and 5% of ichthammol. In whatproportion should they be mixed to prepare a 10% ichthammol ointment?
50%
20% 5%
10% 5 5 40
+ 10 = 50
50% : 20%: 5%
5 : : 50

13. in what proportion may a pharmacist mix 20%, 15% ,5% , 3% zinc oxide ointment to produce 10% ointment
20%
15% 5% 3%
10% 5
20%
15% 5% 3%
10% 7 7 5 OR 10 5 5 10

14. There are 5 types of problems
Mixing of two different concentrations to produce a third intermediate one (as the previous example)
Dilution: mixing of a solution with concentration x% with the free base where a=x% and b=0%
Concentration: mixing of a solution with concentration x% with the active ingredient where a=x% and b=100%
Mixing of 3 different concentrations.
Mixing of 4 different concentrations.

15. Liquid Paraffin emulsion (p.95)Rx
Liquid Paraffin ℥ss 15 ml
Gum Acacia Q.S.
Spirit Mentha min xv (15 x 0.06 = 0.9 ml)
Water to ℥ii 60 ml
Fiat: Haustus
Sig.: Statin
Keep in a Cool Place
Shake The Bottle
The Draught
To be taken at once.

16. Liquid Paraffin is a mineral oil
Prepared using the dry gum method
Uses
It softens fecal contents by retarding water reabsorption, so it is useful in chronic constipation. O W G 3 2 1
15 ml
10 ml
5 gm

17. 10 ml Water on the otherside
Dry gum Method
Trituration must be:
From the wrist.
In one direction.
In all parts of the morter.
Continueous.
Very Fast.
10 ml Water on the otherside
15 ml
Oil on oneside
In a dry mortar; add gum & grind with pestle
Place gum in a line in the center
Triturate with whipping motion until primary emulsion is formed (white , thick ,cracking sound)
Continue triturating for 2 min. (stabilization)

18. Add to emulsion portionwise with stirring
In test tube put 10 ml water ml spirit mentha
Mix well
Add to emulsion portionwise with stirring
10ml Water portion-wise
& triturate
10ml Water
Dpwise &
triturate
Wip with
a tissue
Adjust volume to 60 ml
Transfer to a cup measure
Primary Emulsion

19. Wet gum Method triturate until the gum is dissolved to form mucilage.
adjust volume to 60 ml with water
10ml
Water
dpwise
+ 15 ml
Oil dropwise
& triturate
10ml Water portion-wise
+ 10 ml
water
If a “ropy” appearance, stop the addition of oil , few drops of water should be added until the mixture becomes uniform.
triturate until the gum is dissolved to form mucilage.
Triturate with whipping motion until primary emulsion is formed (white , thick ,cracking sound)
Transfer to a cup measure
In a dry mortar; add gum & grind with pestle
Continue triturating for 2 min. (stabilization)

20. Difference Between Both Methods
Dry gum method
Wet gum method
Oil and water are added at once
Water is added to dissolve the gum then oil is added dropwise
If primary emulsion isn’t formed, can’t be corrected , therefore discard
If ropy appearance , stop oil addition and add few drops of water to maintain the emulsion