What is the difference between "biotin" and "d-biotin".

[Perricone]

What is the difference between "biotin" and "d-biotin". When look for a Biotin supplement, I see both.

[pliny_2001]

It should refer to the structure formed by the particular chemical bonds in a biotin molecule. Assuming that biotin's a molecule, of course, and not just a marketing name -- if it is (marketing), then d, or dl-, or d-alpha, or any other structure note will just be more marketing words.