Phentermine

Phentermine
Clinical data
Trade names	Adipex-P, Ionamin, Suprenza, others
Other names	α,α-Dimethylphenethylamine; α,α-Dimethylphenylethylamine; α-Methylamphetamine
AHFS/Drugs.com	Monograph
MedlinePlus	a682187
Pregnancy; category	AU: B3;
Dependence; liability	Physical: Not typical; Psychological: Moderate
Addiction; liability	Low
Routes of; administration	By mouth
Drug class	Psychostimulant; Appetite suppressant; Norepinephrine–dopamine releasing agent
ATC code	A08AA01 (WHO) A08AA51 (WHO);
Legal status
Legal status	AU: S4 (Prescription only); BR: Class B2 (Anorectic drugs); CA: Schedule IV; DE: Prescription only (Anlage III for higher doses); NZ: Class C; US: Schedule IV;
Pharmacokinetic data
Bioavailability	High (almost 100%)
Protein binding	17.5%
Metabolism	Minimal (6%)
Elimination half-life	20–25 hours, urinary pH-dependent
Excretion	Urine (62–85% unchanged)
Identifiers
	IUPAC name 2-methyl-1-phenylpropan-2-amine;
CAS Number	122-09-8 ;
PubChem CID	4771;
IUPHAR/BPS	7269;
DrugBank	DB00191 ;
ChemSpider	4607 ;
UNII	C045TQL4WP;
KEGG	D05458 ;
ChEBI	CHEBI:8080 ;
ChEMBL	ChEMBL1574 ;
CompTox Dashboard (EPA)	DTXSID9023461 ;
ECHA InfoCard	100.004.112
Chemical and physical data
Formula	C10H15N
Molar mass	149.237 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES NC(Cc1ccccc1)(C)C;
	InChI InChI=1S/C10H15N/c1-10(2,11)8-9-6-4-3-5-7-9/h3-7H,8,11H2,1-2H3 ; Key:DHHVAGZRUROJKS-UHFFFAOYSA-N ;
	(verify)

Phentermine, sold under the brand name Adipex-P among others, is a medication used together with diet and exercise to treat obesity. It is available by itself or as the combination phentermine/topiramate. Phentermine is taken by mouth.

Common side effects include a fast heart beat, high blood pressure, trouble sleeping, dizziness, and restlessness. Serious side effects may include abuse, but do not include pulmonary hypertension or valvular heart disease, as the latter complications were caused by the fenfluramine component of the "fen-phen" combination. Phentermine is a norepinephrine and dopamine releasing agent (NDRA) and produces stimulant, rewarding, and appetite suppressant effects. Chemically, it is a substituted amphetamine.

Phentermine was approved for medical use in the United States in 1959. It is available as a generic medication. In 2022, it was the 149th most commonly prescribed medication in the United States, with more than 3 million prescriptions. Phentermine was withdrawn from the market in the United Kingdom in 2000, while the combination medication fen-phen, of which it was a part, was withdrawn from the market in 1997 due to side effects of fenfluramine.