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

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.

COOH

OH

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

Methods1. Preparation of Cream

IngredientIngredient 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*Dissolve together using a steam bath till at the temperature of 70oC 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.

Methods2.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.

Methods3.Preparation of PasteIngredient Ingredient weight (g)

with Salicylic acidIngredient 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.

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.

Methods

Amount of Salicylic Acid in Dosage Forms

Salicylic Acid (g)

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

Cream Ointment Paste

Dosage Form

Each mL of 0.1 N sodium hydroxide is equivalent to 13.81 mg of salicylic acid.

Results5. 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.