Salicylic Acid Semisolid
Preparations
Faith White
Advisors: Dr. Antoine Al-Achi
&
Mrs. Janice Jackson-Freeman
Objective
The purpose of this experiment was to
determine the distribution of salicylic
acid in creams, ointments, and pastes.
Key Terms
•
•
•
•
Salicylic Acid
Cream
Ointment
Paste
COOH
OH
Salicylic Acid
(C7H6O3)
Salicylic acid is a fine, white powder. It is
used externally on the skin. It helps in the
treatment of athlete’s foot, ringworm of the
scalp, and the removal of warts, corns, and
calluses. Salicylic acid is also incorporated into
preparations for the treatment of acne,
dandruff, seborrhea, and insect bites.
Cream
• Viscous liquid or
semisolid emulsions of
either the
oil/water(o/w) or
water/oil (w/o) type.
Examples:
• O/W type:shaving,
hand, and foundation
creams
• W/O type: cold and
emollient creams
Methods
1. Preparation of Cream
Ingredient
Ingredient weight(g) or
amount(mL) with
Salicylic Acid
Ingredient weight (g) or
amount (mL) without
Salicylic Acid
Water*
19mL
19mL
White Wax (beeswax)+
12g
12g
Spermaceti Wax+
12.5g
12.5g
Mineral Oil+
54g
56g
Sodium Borate*
.5g
.5g
Salicylic Acid
2g
0g
o
*Dissolve together using a steam bath till at the temperature of 70 C
remove from heat, then immediately add salicylic acid.
+Dissolve together using a steam bath till at the temperature of 70oC.
-After both mixtures are at appropriate temperatures add together
stirring rapidly and continuously until it has congealed.
Ointment
• Semisolid preparations
intended for the external
application to the skin or
mucous membranes;
usually contain medicinal
substances; properties
vary.
Methods
2.Preparation of Ointment
Ingredient
Ingredient weight (g) or
amount (mL) with Salicylic
Acid
Ingredient weight (g) or
amount (mL) without
Salicylic Acid
^Sodium Lauryl Sulfate
1g
1g
^Propylene Glycol
12g
12g
#Stearyl alcohol
25g
25g
#White Petrolatum
25g
25g
^Methylparaben
0.025g
0.025g
^Propylparaben
0.015g
0.015g
^water
33mL
35mL
Salicylic Acid
2g
0g
^Dissolve together using a steam bath till at the temperature of 75oC remove from
heat, then immediately add salicylic acid
#Dissolve together using a steam bath till at the temperature of 75oC.
-after both mixtures are at the appropriate temperatures add together stirring
rapidly and continuously until it has congealed.
Paste
• Concentrates of
absorptive powders
dispersed (usually) in
petrolatum or
hydrophilic petrolatum.
Often used in the
treatment of oozing
lesions. Are also used
to restrict the area of
treatment by acting as
an absorbent.
Methods
3.Preparation of Paste
Ingredient
Ingredient weight (g)
with Salicylic acid
Ingredient weight (g)
without salicylic acid
#Zinc Oxide
25g
25g
#Starch
25g
25g
White Petrolatum
48g
50g
Salicylic Acid
2g
0g
#Mix the ingredients together in a mortar and pestle, then add
salicylic acid to mixture and then mix in the white petrolatum.
Preparation of Diluted Alcohol
•
•
•
515 mL of 95% ethyl alcohol USP was
measured using volumetric flask and
graduated cylinder.
500 mL of deionized water was
measured using volumetric flask.
Ethyl alcohol and deionized water was
combined for a 49% alcohol solution.
Preparation of 0.1 N Sodium
Hydroxide
•
8 grams of sodium hydroxide pellets
was weighed and dissolved in
deionized water and filled to 2 L mark
on volumetric flask.
Methods
a. To 25 mL of diluted alcohol (49%), one drop of
phenolphthalein TS and sufficient 0.1 N sodium
hydroxide from a buret was used to produce a faint
pink color.
Methods
b. Five grams from one preparation was
added and mixed for five minutes at 300
rpms on a stir plate.
Methods
c. After the five minutes was up, the liquid in
the flask was clear or white.
Methods
d. Drops of 0.1 N sodium hydroxide from a buret was
added to the flask slowly till a faint pink color developed.
Methods
e. The amount of 0.1 N sodium hydroxide
used was recorded to determine the
precision.
Amount of Salicylic Acid in
Dosage Forms
2.5
Salicylic Acid (g)
2.0
1.5
1.0
0.5
0.0
-0.5
Cream
Ointment
Paste
Dosage Form
Each mL of 0.1 N sodium hydroxide is equivalent to
13.81 mg of salicylic acid.
Results
5. The precision of our preparations.
Preparation
Precision
Cream
45.3%
Ointment
38.4%
Paste
32.6 %
Conclusion
Due to inconsistencies in the
data it was concluded that
maybe there was not sufficient
mixing time for the release of
salicylic acid from the base...
or maybe it was because I
couldn’t stop eating the
paste!!
Acknowledgements
I would like to thank Dr. Al-Achi
for all of his help in completing
this experiment and Mrs.
Freeman for all of her guidance,
time, and patience.