Can Alpha Arbutin Be Used at the Same Time with Hydroquinone?

I suppose you could use them together but why would you. Arbutin is a swarmy, sweet first cousin of hydroquinone. This is my way of saying that Arbutin is glycosylated hydroquinone....hydroquinone with a glucose (sugar) molecule attached. It in fact turns into hydroquinonie as it is broken down. LIke hydroquinone it supresses pigment prodcution by inhibiting the tyrosinase enzyme.
Scientific proponents of arbutin claim that by breaking down into hydroquinone, and working slower, there is less irritation and fewer side effects.
While it is milder than hydroquinone (I did mention the cousin with a better disposition), I am not sure if it is as effective. Concentration would also be important here same as Hydroquinoine 4% works better than hydroquinone 2%.
Many times you might see that a skin care company has used bearberry extract. This usually contains arbutin. Personally, when I make a recommendation ingredient, I like the pure stuff. I am never sure whether the other ingredients might interfere with absorbtion or interact in a non-beneficial way.
In sum, while these two compounds are compatible, I am not sure why you want want two ingredients that are so similar in nature.
Good question and I hope this explanation helps.