you are adding pure hydrocortisone to a cream that already contains hydrocortisone - both must be considered. b. How many milligrams of Hydrocortisone USP (pure powder) and how many grams of Hydrocortisone 1\% Cream would you need to prepare 1lb of this preparation? you are adding pure hydrocortisone to a cream that already contains hydrocortisone - both must be considered. b. How many milligrams of Hydrocortisone USP (pure powder) and how many grams of Hydrocortisone 1\% Cream would you need to prepare 1lb of this preparation