How do I make the next preparation? Hydroquinone 300mg dexamethasone 3mg tretinoin acid 30mg Carbopolgel AD 30g

The combination of these three constituents corresponds to the Kligman ointment. Dexamethasone (0.1%), which is probably added because of its vasoconstriction, poses the least problems.

Hydroquina (normally at Kligman 5%, which is very high) is best limited to 3%. Incompatibilities with PG-emulsifiers are neither proven nor excluded. Based on Question Box experience, I would recommend these emulsifiers anyway. As with each incompatibility also here the concentration probably plays a role. So best not to use Cetomacrogol but Lanette. The incompatibility with HEC, which occurs with the structure related resorcine, does not seem to occur with Hydroquinte.

In Hydroquina preparations occurs rapidly dissolution; without stabilizers no shelf life of 1 month. Different stabilizers are used in various formularies: Vit C 0.6%, after metabisulfite (FNA) 0.5% and acetylcysteine 3% in fatty ointment.

Tretinoine 0.025; 0.05 or 0.1% is insoluble in water and in most ointment and cremeingredients. So mostly suspended! But the available raw material is not fine enough. Therefore, it is dissolved in alcohol and poured into the cremebasis (see FNA; good method?) or dissolved in a lipophilic liquid, which can be processed in the cream. This is BV Cetiol. To increase stability, an antoxidans is used in this case e.g. Butylhydroxytolua.

A cremeformulation in which and Tretinoine and hydroquinone Voooren are worded as follows:

Hydrochinon 1g Tretinoine 100mg BHT 100mg Cetiol V 2g Lactic acid 1g Glycerin 15g Na EDTA 75mg After metabisulfite 500mg Ung Emuslificans, aqua to 100g

A formulation based on a gel with hydroquinone is not to be found. Well for Tretinoine (BASF gives):

tretinoine 0.05 g Ethanol 15g Cremophor 1g BHT 40mg Carbopol 940 (or better 980) 0.5 g Triethanolamine 700mg and water up to 100g

Shelf life 1 year preserved in dark

I suspect dexamethasone is also soluble in the 15g ethanol but will not remain in solution after adding water. Then it is preferable to rub off the dexamethasone with the gel.

comments Thus, it reverts to Tiethanolamine because present product is available with very low levels of nitrosamines! Supplied by BASF which withdraws another commonly used base Neutrol for the sake of nitrosamines. This will set problems for the preparation of gels with very high alcohol concentration given that they are only possible with Neutrol TO!!!

combination with Hydroquina I suspect that hydroquintic is well soluble in the Tretinoin gel. As an additional auxiliary fabric I would still add 0.5 g nametabisulfite; After EDTA 100mg lactic acid We will be omitted due to Carbopol if for some reason it does not work I would try HEC gel. Will tolerate 15% alcohol.