Hydroquinone cream and gel

Hydroquinone is 1,4-benzenediol. Hydroquinone is structurally related to monobenzone. Hydroquinone occurs as fine, white needles. The drug is freely soluble in water and in alcohol and has a pKa of 9.96. Chemically, hydroquinone is designated as p-dihydroxybenzene the empirical formula is C6H602. 

Each gram of 4% cream contains 40 mg of hydroquinone USP in a vanishing-cream base of purified water USP, stearic acid NF, propylene glycol USP, polyoxyl 40 stearate NF, polyoxyethylene (25) propylene glycol stearate, glycerol monostearate, light mineral oil NF, squalane NF, propylparaben NF, and sodium metabisulfite NF. 

Each gram of 4% gel contains 40 mg hydroquinone USP, 50 mg padimate O USP, and 30 mg dioxybenzone USP in a hydro-alcoholic base of alcohol USP, purified water USP, propylene glycol USP, entprol, carbomer 940, edetate disodium USP, and sodium metabisulfite NF. 

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