Phentermine


Description

Phentermine is a sympathomimetic amine anorectic agent and it was introduced in 1959 as part of an anti-obesity combination drug.[1,

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Pharmacology

Indication

Phentermine is indicated, alone or in combination with topiramate, as a short-term adjunct, not pass... Read more

Pharmacodynamic

It is reported that the main mechanism of action of phentermine is the generation of appetite suppre... Read more

Mechanism of action

Phentermine is an indirect-acting sympathomimetic agent that acts by releasing noradrenaline from th... Read more

Absorption

Phentermine shows a dose-dependent pharmacokinetic profile. After oral administration of a dose of 1... Read more

Protein binding

The protein binding of phentermine is determined to be of 17.5%.[ Read more

Volume of distribution

The reported volume of distribution for phentermine is reported to be of 5 L/kg.[ Read more

Clearance

The reported clearance when administered orally is 8.79 L/h as observed in pharmacokinetic populatio... Read more

Half life

The mean terminal half-life of phentermine is reported to be of approximately 20 hours.[ Read more

Route of elimination

Phentermine is excreted mainly in the urine from which about 70-80% of the administered dose can be... Read more

Toxicity

The reported LD50 after oral administration of phentermine in rats is reported to be of 151 mg/kg.[ Read more


Adverse Effects

Effect Regions Age Groups Incidences Evidence Type
Constipation US
  • Kind: experimental
    • Percent: 15.1
  • Kind: placebo
    • Percent: 6.1
  • Clinical Trial
    Paraesthesia US
  • Kind: experimental
    • Percent: 13.7
  • Kind: placebo
    • Percent: 1.9
  • Clinical Trial
    Dry Mouth US
  • Kind: experimental
    • Percent: 13.5
  • Kind: placebo
    • Percent: 2.8
  • Clinical Trial
    Upper Respiratory Tract Infection US
  • Kind: experimental
    • Percent: 12.2
  • Kind: placebo
    • Percent: 12.8
  • Clinical Trial
    Nasopharyngitis US
  • Kind: experimental
    • Percent: 10.6
  • Kind: placebo
    • Percent: 8
  • Clinical Trial
    Headache US
  • Kind: experimental
    • Percent: 7
  • Kind: placebo
    • Percent: 9.3
  • Clinical Trial
    Dysgeusia US
  • Kind: experimental
    • Percent: 7.4
  • Kind: placebo
    • Percent: 1.1
  • Clinical Trial
    Dizziness US
  • Kind: experimental
    • Percent: 7.2
  • Kind: placebo
    • Percent: 3.4
  • Clinical Trial
    Sinusitis US
  • Kind: experimental
    • Percent: 6.8
  • Kind: placebo
    • Percent: 6.3
  • Clinical Trial
    Insomnia US
  • Kind: experimental
    • Percent: 5.8
  • Kind: placebo
    • Percent: 4.7
  • Clinical Trial
    Back Pain US
  • Kind: experimental
    • Percent: 5.6
  • Kind: placebo
    • Percent: 5.1
  • Clinical Trial
    Urinary Tract Infection(UTI) US
  • Kind: experimental
    • Percent: 5.2
  • Kind: placebo
    • Percent: 3.6
  • Clinical Trial
    Influenza US
  • Kind: experimental
    • Percent: 4.6
  • Kind: placebo
    • Percent: 4.4
  • Clinical Trial
    Bronchitis US
  • Kind: experimental
    • Percent: 4.4
  • Kind: placebo
    • Percent: 4.2
  • Clinical Trial
    Fatigue US
  • Kind: experimental
    • Percent: 4.4
  • Kind: placebo
    • Percent: 4.3
  • Clinical Trial
    Nausea US
  • Kind: experimental
    • Percent: 3.6
  • Kind: placebo
    • Percent: 4.4
  • Clinical Trial
    Vision blurred US
  • Kind: experimental
    • Percent: 4
  • Kind: placebo
    • Percent: 3.5
  • Clinical Trial
    Cough US
  • Kind: experimental
    • Percent: 3.8
  • Kind: placebo
    • Percent: 3.5
  • Clinical Trial
    Hypoesthesia US
  • Kind: experimental
    • Percent: 3.6
  • Kind: placebo
    • Percent: 1.2
  • Clinical Trial
    Gastroesophageal Reflux Disorder US
  • Kind: experimental
    • Percent: 3.2
  • Kind: placebo
    • Percent: 1.3
  • Clinical Trial
    Musculoskeletal Pain US
  • Kind: experimental
    • Percent: 3
  • Kind: placebo
    • Percent: 1.2
  • Clinical Trial
    Pain in extremity US
  • Kind: experimental
    • Percent: 3
  • Kind: placebo
    • Percent: 2.8
  • Clinical Trial
    Muscle spams US
  • Kind: experimental
    • Percent: 2.8
  • Kind: placebo
    • Percent: 2.2
  • Clinical Trial
    Depression US
  • Kind: experimental
    • Percent: 2.8
  • Kind: placebo
    • Percent: 2.2
  • Clinical Trial
    Sinus Congestion US
  • Kind: experimental
    • Percent: 2.6
  • Kind: placebo
    • Percent: 2
  • Clinical Trial
    Alopecias US
  • Kind: experimental
    • Percent: 2.6
  • Kind: placebo
    • Percent: 0.7
  • Clinical Trial
    Irritability US
  • Kind: experimental
    • Percent: 2.6
  • Kind: placebo
    • Percent: 0.7
  • Clinical Trial
    Procedural Pain US
  • Kind: experimental
    • Percent: 2.4
  • Kind: placebo
    • Percent: 1.7
  • Clinical Trial
    Palpitations US
  • Kind: experimental
    • Percent: 2.4
  • Kind: placebo
    • Percent: 0.8
  • Clinical Trial
    Neck Pain US
  • Kind: experimental
    • Percent: 2.2
  • Kind: placebo
    • Percent: 1.3
  • Clinical Trial
    Gastroenteritis US
  • Kind: experimental
    • Percent: 2.2
  • Kind: placebo
    • Percent: 2.2
  • Clinical Trial
    Rash US
  • Kind: experimental
    • Percent: 2
  • Kind: placebo
    • Percent: 2.2
  • Clinical Trial
    Eye Pain US
  • Kind: experimental
    • Percent: 2.2
  • Kind: placebo
    • Percent: 1.4
  • Clinical Trial
    Dyspepsia US
  • Kind: experimental
    • Percent: 2.2
  • Kind: placebo
    • Percent: 1.7
  • Clinical Trial
    Pharyngolaryngeal pain US
  • Kind: experimental
    • Percent: 1.2
  • Kind: placebo
    • Percent: 2
  • Clinical Trial
    Disturbance in attention US
  • Kind: experimental
    • Percent: 2
  • Kind: placebo
    • Percent: 0.6
  • Clinical Trial
    Anxiety US
  • Kind: experimental
    • Percent: 1.8
  • Kind: placebo
    • Percent: 1.9
  • Clinical Trial
    Appetite decreased US
  • Kind: experimental
    • Percent: 1.8
  • Kind: placebo
    • Percent: 0.6
  • Clinical Trial
    Thirst US
  • Kind: experimental
    • Percent: 1.8
  • Kind: placebo
    • Percent: 0.7
  • Clinical Trial
    Nasal Congestion US
  • Kind: experimental
    • Percent: 1.2
  • Kind: placebo
    • Percent: 1.4
  • Clinical Trial
    Hypokalemia US
  • Kind: experimental
    • Percent: 1.4
  • Kind: placebo
    • Percent: 0.4
  • Clinical Trial
    Dry Eye US
  • Kind: experimental
    • Percent: 1.4
  • Kind: placebo
    • Percent: 0.8
  • Clinical Trial
    Dizziness US
  • Kind: experimental
    • Percent: 1.2
  • Kind: placebo
    • Percent: 0.2
  • Clinical Trial
    Paraesthesia US
  • Kind: experimental
    • Percent: 1
  • Kind: placebo
    • Percent: 0
  • Clinical Trial
    Depression US
  • Kind: experimental
    • Percent: 0.8
  • Kind: placebo
    • Percent: 0.2
  • Clinical Trial
    Irritability US
  • Kind: experimental
    • Percent: 0.8
  • Kind: placebo
    • Percent: 0.1
  • Clinical Trial
    Vision blurred US
  • Kind: experimental
    • Percent: 0.8
  • Kind: placebo
    • Percent: 0.5
  • Clinical Trial
    Headache US
  • Kind: experimental
    • Percent: 0.2
  • Kind: placebo
    • Percent: 0.6
  • Clinical Trial
    Paraesthesia oral US
  • Kind: experimental
    • Percent: 0.6
  • Kind: placebo
    • Percent: 0.3
  • Clinical Trial
    Insomnia US
  • Kind: experimental
    • Percent: 0.4
  • Kind: placebo
    • Percent: 0.4
  • Clinical Trial

    Contraindications

    • Hypersensitivity:
      • true
    • Regions: US
    • Route:
      • Oral
    • Dose Form:
      • Capsule
      • Tablet
      • Tablet, orally disintegrating
    • Regions: US
    • Patient Conditions:
        • Name: Nursing
        • Drugbank Id: DBCOND0040121
    • Route:
      • Oral
    • Dose Form:
      • Capsule
      • Tablet
      • Tablet, orally disintegrating
    • Regions: US
    • Patient Conditions:
        • Name: Pregnancy
        • Drugbank Id: DBCOND0018394
    • Route:
      • Oral
    • Dose Form:
      • Capsule
      • Tablet
      • Tablet, orally disintegrating
    • Regions: US
    • Patient Conditions:
        • Name: History of drug abuse
        • Drugbank Id: DBCOND0107489
    • Route:
      • Oral
    • Dose Form:
      • Capsule
      • Tablet
      • Tablet, orally disintegrating
    • Regions: US
    • Patient Conditions:
        • Name: Agitated state
        • Drugbank Id: DBCOND0107488
    • Route:
      • Oral
    • Dose Form:
      • Capsule
      • Tablet
      • Tablet, orally disintegrating
    • Regions: US
    • Patient Conditions:
        • Name: Glaucoma
        • Drugbank Id: DBCOND0010013
    • Route:
      • Oral
    • Dose Form:
      • Capsule
      • Tablet
      • Tablet, orally disintegrating
    • Regions: US
    • Patient Conditions:
        • Name: Hyperthyroidism
        • Drugbank Id: DBCOND0009048
    • Route:
      • Oral
    • Dose Form:
      • Capsule
      • Tablet
      • Tablet, orally disintegrating
    • Regions: US
    • Patient Conditions:
        • Name: Concomitant use or 14 days after discontinuation
        • Drugbank Id: DBCOND0117358
    • With Categories:
        • Name: Monoamine Oxidase Inhibitors
        • Drugbank Id: DBCAT001004
        • Mesh Id: D008996
    • Route:
      • Oral
    • Dose Form:
      • Capsule
      • Tablet
      • Tablet, orally disintegrating
    • Regions: US
    • Patient Conditions:
        • Name: History of cardiovascular disease
        • Drugbank Id: DBCOND0102767

    Food Interactions

    • Limit caffeine intake.
    • Take without regard to meals.

    Interactions

    Type in a drug name to check for interaction with Phentermine

    The metabolism of (R)-warfarin can be decreased when combined with Phentermine.
    The metabolism of (S)-Warfarin can be decreased when combined with Phentermine.
    The risk or severity of hypertension can be increased when Phentermine is combined with 1-(3-Mercapto-2-Methyl-Propionyl)-Pyrrolidine-2-Carboxylic Acid.
    The therapeutic efficacy of 1-benzylimidazole can be decreased when used in combination with Phentermine.
    The therapeutic efficacy of 2,4-thiazolidinedione can be increased when used in combination with Phentermine.
    The risk or severity of serotonin syndrome can be increased when Phentermine is combined with 2,5-Dimethoxy-4-ethylamphetamine.
    The risk or severity of serotonin syndrome can be increased when Phentermine is combined with 2,5-Dimethoxy-4-ethylthioamphetamine.
    The risk or severity of adverse effects can be increased when Phentermine is combined with 3-isobutyl-1-methyl-7H-xanthine.
    The risk or severity of adverse effects can be increased when Phentermine is combined with 3,5-diiodothyropropionic acid.
    The risk or severity of adverse effects can be increased when Phentermine is combined with 3,5-Diiodotyrosine.
    The risk or severity of serotonin syndrome can be increased when Phentermine is combined with 4-Bromo-2,5-dimethoxyamphetamine.
    The metabolism of 4-hydroxycoumarin can be decreased when combined with Phentermine.
    The risk or severity of hypertension can be increased when Phentermine is combined with 4-Methoxyamphetamine.
    The metabolism of 5-androstenedione can be decreased when combined with Phentermine.
    The risk or severity of serotonin syndrome can be increased when Phentermine is combined with 5-methoxy-N,N-dimethyltryptamine.
    The metabolism of Phentermine can be decreased when combined with 6-Deoxyerythronolide B.
    The risk or severity of adverse effects can be increased when Phentermine is combined with 6-O-benzylguanine.
    The risk or severity of adverse effects can be increased when Phentermine is combined with 7-Deazaguanine.
    The metabolism of Phentermine can be decreased when combined with 7-ethyl-10-hydroxycamptothecin.
    7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline may increase the hypertensive activities of Phentermine.

    References

    • 1 . Johnson DB, Quick J: Topiramate And Phentermine . [PubMed: 29489234]
    • 2 . Ryder JR, Kaizer A, Rudser KD, Gross A, Kelly AS, Fox CK: Effect of phentermine on weight reduction in a pediatric weight management clinic. Int J Obes (Lond). 2017 Jan;41(1):90-93. doi: 10.1038/ijo.2016.185. Epub 2016 Oct 24. [PubMed: 27773937]
    • 3 . Kiortsis DN: A review of the metabolic effects of controlled-release Phentermine/Topiramate. Hormones (Athens). 2013 Oct-Dec;12(4):507-16. [PubMed: 24457398]
    • 4 . Garvey WT: Phentermine and topiramate extended-release: a new treatment for obesity and its role in a complications-centric approach to obesity medical management. Expert Opin Drug Saf. 2013 Sep;12(5):741-56. doi: 10.1517/14740338.2013.806481. Epub 2013 Jun 6. [PubMed: 23738843]
    • 5 . Bersoux S, Byun TH, Chaliki SS, Poole KG: Pharmacotherapy for obesity: What you need to know. Cleve Clin J Med. 2017 Dec;84(12):951-958. doi: 10.3949/ccjm.84a.16094. [PubMed: 29244650]
    • 6 . Weigle DS: Pharmacological therapy of obesity: past, present, and future. J Clin Endocrinol Metab. 2003 Jun;88(6):2462-9. doi: 10.1210/jc.2003-030151. [PubMed: 12788841]
    • 7 . Adebonojo FO: Primary exogenous obesity. A conceptual classification. Clin Pediatr (Phila). 1974 Sep;13(9):715-8. doi: 10.1177/000992287401300901. [PubMed: 4415200]
    • 8 . May S. (2009). Weight-Loss Drugs. Chelsea House Publishers.
    • 9 . Barceloux D.G. (2012). Medical toxicology of drug abuse: Synthesized chemicals and psychoactive plants.. Wiley.
    • 10 . EmpowerPharmacy [Link]
    • 11 . Inchem [Link]
    • 12 . FDA reports [Link]
    • 13 . QSYMIA (phentermine/topiramate) FDA label [File]

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