Remains next creme 2 months stable: hydroquinone 5%, Tretinoin 0035%, hydrocortisone acetate 1% in cremor non ionicum aquosus;

Creams with Tretinoin have often been discussed in the past and are published on   the website. Also in combination with Hydroquina.  

It is clear that certain excipients such as e.g. an antioxydance are both water-soluble and oil-soluble. Under this condition and kept in the refrigerator is a shelf life of 2 months feasible.