Phentermine 375 is just a play on the name of the legal and approved weight loss drug phentermine. True phentermine is only available by prescription and should only be prescribed for short periods for the morbidly obese.
This blend of herbs, spices, and caffeine contains capsaicin which is - chili powder. It claims another ingredient is similar to ephedra - a banned weight loss drug. Another is supposed to be chemically related to an amphetamine. Another is just dehydrated caffeine. They put a bunch of scientific names on a bunch of common names to make it sound impressive or to hide the ingredients.
It is not approved by any medical, regulatory, or dietary organization. This product must be sold as a dietary supplement. Unfortunately the Dietary Supplement act of 1994 allows for the sale of the bogus weight loss pills.
Phentermine is a controlled substance and it is illegal to sell without a prescription. It is illegal to sell phentermine without a prescription.
What is interesting is the phentermine 375 web page does not name the manufacturer.