phentermine (Adipex-P, Lomaira)

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

  • Medical and Pharmacy Editor: Charles Patrick Davis, MD, PhD
    Charles Patrick Davis, MD, PhD

    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

Is phentermine available as a generic drug?

Yes

Do I need a prescription for phentermine?

Yes. It is a schedule IV controlled substance.

Why is phentermine prescribed to patients?

  • Phentermine is combined with diet and exercise for the short-term treatment of obesity in individuals with a body mass index greater than or equal to 30 kg/m2 or greater than or equal to 27 kg/m2 with risk factors for heart disease.
  • Phentermine should not be combined with other weight loss agents.
  • The combination of phentermine and fenfluramine (FEN-PHEN) is associated with serious heart problems. Fenfluramine is no longer available in the United States.

What are the side effects of phentermine?

Side effects of phentermine include:

Central nervous system side effects include:

Phentermine, especially when combined with fenfluramine, has been associated with high pressures in the pulmonary arteries (pulmonary hypertension) and defects in heart valves, both serious complications.

Physical and psychological dependence may occur with the long-term use of phentermine. A withdrawal reaction, which includes excessive drowsiness, fatigue, tremors and depression may occur after prolonged use.

What is the dosage for phentermine?

  • The recommended dose is 15-37.5 mg once daily.
  • Adipex-P is administered about 1-2 hours after breakfast.
  • The lowest effective dose should be used and evening doses should be avoided because phentermine causes insomnia.

Which drugs or supplements interact with phentermine?

  • Phentermine is similar to amphetamine and may share some of the interactions associated with amphetamines. Combining phentermine with tricyclic antidepressants (for example, amitriptyline [Elavil, Endep]) or monoamine oxidase inhibitors or MAOIs (for example, phenelzine [Nardil], selegiline [Zelapar, Emsam, and Eldepryl], tranylcypromine [Parnate]) may result in high blood pressure and other serious reactions because of elevated serotonin levels in the blood. Phentermine should not be used within 14 days after stopping a monoamine oxidase inhibitor.
  • People with diabetes being treated with phentermine may require a reduction in their dose of insulin or oral hypoglycemic drug.
  • Combining alcohol with phentermine may result in an adverse drug reaction.

Is phentermine safe to use during pregnancy or while breastfeeding?

  • Use of phentermine during pregnancy has not been adequately evaluated.
  • It is not known whether phentermine is excreted in human breast milk. Since other amphetamines are excreted in breast milk, phentermine should not be used while breastfeeding or, if used, nursing should be discontinued.

What else should I know about phentermine?

What preparations of phentermine are available?
  • Tablets: 8 and 37.5 mg.
  • Capsules: 15, 30, 37.5 mg.
How should I keep phentermine stored?

Phentermine should be stored in a tight container at room temperature, 20 C to 25 C (68 F to 77 F).

How does phentermine work?
  • The exact mechanism of action of phentermine is unknown. It probably decreases appetite by acting on centers in the brain that control appetite. Phentermine is similar to amphetamine. It stimulates the nervous system, elevates blood pressure, and increases heart rate.

Reference: FDA Prescribing Information

Summary

Phentermine (Adipex-P, Lomaira, [Discontinued brands: Fastin, Oby-Trim, Obestin-30, OnaMast, Tora, Wilpo, Obenix, Suprenza) is a drug that suppresses the appetite for weight loss. Phentermine should be combined with exercise and diet for the short term treatment of obesity. Drug interactions may occur with some tricyclic antidepressants or monoamine oxidase inhibitors. Side effects include

Treatment & Diagnosis

Medications & Supplements

Prevention & Wellness

Subscribe to MedicineNet's Weight Loss/Healthy Living Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

See more info: phentermine on RxList
Reviewed on 10/28/2016
References
Reference: FDA Prescribing Information

Health Solutions From Our Sponsors