Description

Simple

A medication used temporarily to promote weight loss along with other methods, such as exercise and diet changes.

Clinical

A sympathomimetic anorectic agent used as a short-term adjunct therapy that is included in a regimen of weight reduction in cases of exogenous obesity.

Overview

Phentermine is a sympathomimetic amine anorectic agent and it was introduced in 1959 as part of an anti-obesity combination drug.[1, 2] It is chemically related to amphetamine and it is commonly referred to as an atypical amphetamine.[4] Phentermine has not been reported an addictive potential which allows this agent to be classified under the Schedule IV drugs (low abuse potential).[3]

Phentermine was FDA approved for short-term weight management in 1959 and it became widely used in 1960. This initial product, formed by the combination of phentermine with [fenf... Read more

Pharmacology

Indication

Phentermine is indicated, alone or in combination with topiramate, as a short-term adjunct, not pass a few weeks, in a regimen of weight reduction based on exercise, behavioral modifications and caloric restriction in the management of exogenous obesity for patients with an initial body mass index (... Read more

Pharmacodynamic

It is reported that the main mechanism of action of phentermine is the generation of appetite suppression, maybe due to the increase in leptin, but it is considered that other mechanisms should be involved.[ Read more

Mechanism of action

Phentermine is an indirect-acting sympathomimetic agent that acts by releasing noradrenaline from the presynaptic vesicles in the lateral hypothalamus. This increase in noradrenaline concentration in the synaptic cleft results in the stimulation of beta2-adrenergic receptors.[ Read more

Absorption

Phentermine shows a dose-dependent pharmacokinetic profile. After oral administration of a dose of 15 mg, the maximal concentration was achieved after 6 hours and its bioavailability was not affected by the consumption of high-fat meals.[ 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.[11]

Clearance

The reported clearance when administered orally is 8.79 L/h as observed in pharmacokinetic population studies.[13]

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 found as the unchanged drug.[ Read more

Toxicity

The reported LD50 after oral administration of phentermine in rats is reported to be of 151 mg/kg.[12] Reports of acute overdose include restlessness, tremors, hyperreflexia, rapid respiration, confusion, assaultiveness, halluc... 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 with or without food. The absorption is unaffected by food.