DDr. Total nonscents is a superb product! Highly recommend. Though I worry that Sephora might not be carrying it any more(??)
That said, you can get the same kind of effect, perhaps even a bit more rapid results using two products that target your concerns.
Because of routine exfoliation with a razor, you'll want to take a gentle approach or risk sensitivity and irritation, something like Ole Henricksen's Enlighten serum would be perfect! It's a very lightweight serum for evening out skintone no matter what the underlying cause (or area affected). It's got comparable clinical results to a hydroquinone (considered the gold standard for breaking up areas of dark pigmentation) product, but Enlighten is a more natural product that blends several botanical ingredients to lighten you up in no time!
A very important note: given that deodorants and antiperspirants are going to use a hearty base of wax, dimethicone or other impermiabale barrier, you'll need to put the serum on straight out of the shower when your skin has dried, or the serum has no chance of getting through to your skin.
As far as D/Os and A/Ps go, La Vanilla makes a nice one that helps to keep skin calm and happy, especially while trying to treat pigmentation that would be helpful, L'Occitaine makes a lovely roll-on that 's waxy buildup-freehas a nice fresh, crisp scent from a blend of essential oils that neutralize odors--this might be your best option at least while lightening the area, as there will be less wax or dimeth buildup to work through.
I recommend the Dermadoctor Total Nonscents. Its an antiperspirant and gradually lightens the under arm area. If the problem still is an issue for you, I suggest contacting your Dermatologist. I hope that this helps!
I don't know if Sephora carries it anymore or not but DermaDoctor has a brightening deoderant meant to fade underarm discoloration. You can read about it here http://www.sephora.com/total-nonscents-P73514 but it doesn't give you the option to choose between the regular or brightening (site glitch perhaps?)