Phentermine

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Phentermine

Clinical data
Trade names	Ionamin, Suprenza, others
Other names	α-methyl-amphetamine α,α-dimethylphenethylamine
AHFS/Drugs.com	Monograph
MedlinePlus	a682187
Pregnancy category	AU: B3
Dependence liability	Physical: not typical Psychological: Moderate[1]
Addiction liability	Low[2]
Routes of administration	By mouth
Drug class	Appetite suppressant[3]
ATC code	A08AA01 (WHO)
Legal status
Legal status	AU: S4 (Prescription only) BR: Class B2 (Anorectic drugs)[4] CA: Schedule IV DE: Prescription only (Anlage III for higher doses) NZ: Class C US: Schedule IV
Pharmacokinetic data
Bioavailability	High (almost complete)[5]
Protein binding	Approximately 96.3%
Metabolism	Liver[5]
Elimination half-life	25 hours, urinary pH-dependent[5]
Excretion	Kidney (62–85% unchanged)[5]
Identifiers
IUPAC name 2-methyl-1-phenylpropan-2-amine
CAS Number	122-09-8 Y
PubChem CID	4771
IUPHAR/BPS	7269
DrugBank	DB00191 Y
ChemSpider	4607 Y
UNII	C045TQL4WP
KEGG	D05458 Y
ChEBI	CHEBI:8080 Y
ChEMBL	ChEMBL1574 Y
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 Y Key:DHHVAGZRUROJKS-UHFFFAOYSA-N Y
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Phentermine (phenyl-tertiary-butyl amine), sold under the brand name Ionamin among others, is a medication used together with diet and exercise to treat obesity.^[3] It is taken by mouth for up to a few weeks at a time, after which the benefits subside.^[3] It is also available as the combination phentermine/topiramate.^[6]

Common side effects include a fast heart beat, high blood pressure, trouble sleeping, dizziness, and restlessness.^[3] Serious side effects may include abuse, but do not include pulmonary hypertension or valvular heart disease, as the latter were caused by the fenfluramine component of the fen-phen drug combination.^[3] Use is not recommended during pregnancy or breastfeeding,^[7] or with SSRIs or MAO inhibitors.^[3] It works mainly as an appetite suppressant, likely as a result of being a CNS stimulant.^[3] Chemically, phentermine is a substituted amphetamine.^[8]

Phentermine was approved for medical use in the United States in 1959.^[3] It is available as a generic medication.^[3] In 2022, it was the 149th most commonly prescribed medication in the United States, with more than 3 million prescriptions.^[9][10] 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^[11] of fenfluramine which caused increased levels of circulating serotonin which stimulated serotonin receptors on heart valves and thus causing valve insufficiency and leading to primary pulmonary hypertension (PPH). According to the NIH (National Institutes of Health) there is no evidence that phentermine causes PPH.^{[citation needed]}