Question
Posted on: August 23 2018Following preparation with: Salicylic Acid 1%, lactic acid 10%, urea 10% in lipophilic Creme ad 300 g, gives problems.
Answer
Sorbitansesquioleate is an ester of sorbitan and oiieic acid. The water phase of your cream is quite acidic due to the presence of a large amount of lactic acid so that it is not excluded that the W/O emulsifier is slowly hydrolyzing. Degradation products have no more emulgatorical properties.
There are two solutions
1. You prepare AVA yourself with 5 g less water, which you replace with 5 G cetyl- or cetostearyl alcohol.
2. For lipophilic cream make use of Unguentum cetylitic Aqua
Per 100 g is the composition cetyl alcohol 2.8 g; wool grease 7 g; Vaseline 60.2 G and water 30 g