Please provide a triple bleaching cream therapy containg hydrocortisone (or any low-potency corticosteroid, hydroquinone , and retin-A. How long will this cream be stable?

I can propose the following formula:

Hydroquinone 2.5 g
Hydrocortisone acetate 500 mg
Tretinoine (Retinoic acid) 25 mg
Lactic acid 500 mg
Glycerine 5 g
Ascorbic acid 500 mg
Disodium EDTA 75 mg
White beeswax 3 g
Cetaceum 2.5 g
Cetiol 15.5 g
Span 80 1 g
Arlacel C 4 g
Freshly boiled water ad 50 g

COMMENTS

I cannot give stability data for this cream. However several precautions (antioxidant, pH) are taken to make the preparation as stable as possible. But I would still advice to store the cream in the fridge! And not to use it longer than two months. Might I find more information on this item I shall inform you.
Normally a stronger corticosteroid is added as for example triamcinolone acetonide. But this would make a prescription obligatory at least in my country. I hope this composition will give satisfaction? The cream is of the W/O type. Probably to have a slower release and to protect in some way some ingredients for oxidation.