Question
Posted on: March 6 2013I have a problem with following hydroquinone + Tretinoine creme with: Tretinoin 0.1% hydroquinone 4% glycerol 10% ung aquosum Cream Aqua AD 50 gr
after processing the ingredients the whole seemed to me to be grainy so once fed through the ointment mill. After a few days the patient comes back the tube completely!!!
Answer
I think we should start to look at the solubility of Hydroquinte.
In Water: 59g/L at 15 °C; 70g/L at 25 °C; 94G/L at 28 °C. In organic solvents: Soluble in most polar organic solvents (in glycerin apparently 1 to 1) In ethyl alcohol: 57g/100 grams at 25 °C and in acetone 20g/100g at 25 °C Virtually insoluble (< 0.1%) In benzene, toluene and carbon tetrachlorides
So basically all hydroquina should dissolve in the mixture water-glycerin. This probably also makes it much more reactive. I have here a formula for a composition 0.05% and 5%. This does not contain glycerin but a LIMITED amount of ethanol. I suppose this cream gives satisfaction.
Hydroquina 5g Tretinoin 50 mg Sorbic acid 100 mg Lanette N 17g Antisept OPL. 20g BHT 40mg Cetiol V 11.5 g Na2EDTA 50 mg Nametabisulfite 0.5 g Sorbitol 70% Liquid 3g Water up to 100 g
BHT, Hydroquina and Tretionine are dissolved in the antisept. Opl., if necessary under heating. With the other ingredients, the cream is made in which Nametabisulfite, Na2EDTA and sorbic acid are dissolved in the water. The total weight of the cream is 75g. On the cooled cream, the ethanolic solution is added under blending. This cream is 4 months shelf life at KT.
Response (due to Apoth. M. Van Herzele) In the adjusted formula the Hydroquinone stands at 5%. The usual dose is between 1% and 4%.