Physicochemical Stability of Compounded Creams Containing a-Hydroxy Acids.

Area of Science:

• Cosmetic Science
• Pharmaceutical Formulation
• Dermatology

Background:

• Alpha-hydroxy acids (AHAs) like lactic and glycolic acid are popular skincare ingredients.
• Extemporaneous compounding of AHA creams requires careful consideration of formulation stability.
• Understanding the impact of freeze-thaw cycles on AHA cream stability is crucial for product shelf-life.

Purpose of the Study:

• To evaluate the stability of creams containing lactic acid and glycolic acid after freeze-thaw cycles.
• To compare the stability of AHA creams formulated with aqueous cream, BP and hydrophilic ointment, USP.
• To investigate the effect of AHAs on preservative efficacy and potential hydrolysis.

Main Methods:

• Creams with alpha-hydroxy acids (AHAs) were prepared using aqueous cream, BP or hydrophilic ointment, USP.
• Formulations underwent five freeze-thaw cycles between -4°C and 40°C.
• Stability parameters including pH, viscosity, spreadability, density, appearance, and potency were measured post-cycle.

Main Results:

• Creams compounded with hydrophilic ointment, USP exhibited superior stability.
• The addition of AHAs significantly reduced preservative (methylparaben, propylparaben) levels.
• Preservative hydrolysis was prevented in hydrophilic creams when AHAs were neutralized to a pH above 3.5.

Conclusions:

• Hydrophilic ointment, USP is a suitable base for stabilizing AHA-containing creams.
• Formulators must address potential preservative depletion when incorporating AHAs.
• Partial neutralization of AHAs to pH > 3.5 can maintain preservative integrity in hydrophilic formulations.