Phendimetrazine functions as a prodrug to phenmetrazine, and approximately 30% of any given oral dose is converted into it. Phendimetrazine can essentially be thought of as an extended release and less abusable version of phenmetrazine. Phenmetrazine (and therefore phendimetrazine as well) acts as a norepinephrine-dopamine releasing agent (NDRA).^[2]

Its structure incorporates the backbone of methamphetamine, a potent CNS stimulant. Whilst adding an N-methyl group to the structure of amphetamine significantly increases its potency and bioavailability, in the case of phendimetrazine the added methyl group results in the compound becoming virtually inactive, at least until the methyl group is removed by the body's metabolism. This results in a steady, continued activation of the drug in the body, both lowering abuse potential and allowing for once-daily administration. However, the abuse potential is significantly high that it is only rarely prescribed today.

Phendimetrazine is as potent as amphetamine and is a Schedule III drug under the Convention on Psychotropic Substances. In the United States, phendimetrazine is a Schedule III controlled substance under the Uniform Controlled Substances Act of 1970.

According to the "List of psychotropic substances under international control", phendimetrazine is a Schedule IV controlled substance.^[3] Phendimetrazine is listed as a Schedule III substance under the U.S. Controlled Substance Act in the 2007 Drug Identification Bible, pg 615 and under Section 11056(b)(6) California Health and Safety Code.