Question
Posted on: March 6 2013Precipitate of salicylic acid in following preparation: Clobetasolpropionate 15mg Salicylic Acid 2.4 G Klucel GF 1.8 g propylene glycol 18ml aqua dest. 15ml F. Gel
Intent a slight gel, which is easy to apply on a rough spot hairy scalp.
used Preparation method: Dissolve salicylic acid and clobetasolpropionate in propylene glycol (clear solution). To rub the klucel with this solution in mortar. This gives a fairly homogeneous clear somewhat fishkeuzer mixture. When adding the water the mixture is returned less viscous and becomes white colored and less homogeneous.
Is The concentration of salicylic acid too high for this preparation and stores salicylic acid when adding water? If so, how much salicylic acid can be processed in this gel?
Answer
This seems to me to be a peculiar composition. The total quantity is 37.2 g (density PG = 1)? I would put this on 40g and increase the amount of PG to 21g. Such amount of salicylic acid can never remain in solution. How much can be processed in this mixture PG + H2O should be experimentally determined. You should therefore add small weighed amounts of salicylic acid to this solvent mixture to saturation. Then with this solution you can rub off the mixture of clobetasolpropionate and Klucel. If the viscosity is too low, the quantity of the Klucel can be increased to 2.5 G.