Phentermine HCl (Commercial)

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Phentermine is a prescription medication used as an appetite suppressant to aid in weight loss for individuals with obesity or weight-related medical conditions. It is typically used short-term in combination with diet, exercise, and behavioral changes to enhance weight reduction.

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ACTIVE INGREDIENTS
Phentermine Hydrochloride
HOW TO USE
Weight management
Take 37.5 mg orally once daily before breakfast or 1 to 2 hours after breakfast; some patients may require 18.75 mg once daily or a divided dose of 18.75 mg twice daily based on patient-specific factors.
DISCLAIMER
This compounded medication is only available when the commercially available product is unavailable or when a prescriber determines that there is a clinically significant difference for the patient.

Medicine Information

Potential Benefits

Helps reduce appetite
Decreases caloric intake
Enhances adherence to dietary changes

Treament Protocol

Legal

Storage Instructions

Warnings

Use in Specific Populations

Avoid use during pregnancy.
Avoid use in nursing mothers.
Not recommended for pediatric patients. Safety and effectiveness have not been established because pediatric obesity is chronic and requires long-term treatment approaches.
Use in geriatrics is generally not recommended. If therapy is initiated, it is recommended to start at the lowest dose and to monitor renal, hepatic, and cardiac function prior to starting.
Use caution when administering phentermine to patients with renal impairment (eGFR 15 to 29 mL/min/1.73m²), limit dose to 15mg daily. Avoid use in patients with eGFR less than 15mL/min/1.73m².

Precautions

May cause insomnia, agitation, and restlessness.
May cause sudden increases in heart rate and blood pressure; caution in patients with cardiovascular disease.
May worsen anxiety or agitation.
Potential for dependency as a stimulant.
Avoid or use with caution in patients with history of seizures.
Use with caution in patients with diabetes mellitus as some diabetic medications may need to be adjusted.
Tolerance usually develops within a few weeks. Discontinue use when tolerance develops and do not increase recommended dosing in an attempt to combat tolerance.

Manufacturer Info

How It Works

Phentermine is a sympathomimetic amine with pharmacologic activity comparable to that of amphetamines. Its anorectic effect is primarily attributed to central nervous system stimulation, notably the activation of the hypothalamic pathways leading to increased release of norepinephrine which may help reduce hunger thus lowering caloric intake.

F.A.Q

How long can I take phentermine?

Phentermine is usually prescribed for short-term use (generally 3–12 weeks), but some doctors may extend use in certain cases with careful monitoring.

How quickly will I lose weight on phentermine?

Weight loss can vary. However many patients can expect to begin losing weight within the first week or two with proper diet and exercise.

Can I drink coffee or take other stimulants while taking phentermine?

It’s important to use caution when combining phentermine with other stimulants like caffeine, pre-workout supplements, energy drinks, or decongestants. Doing so may intensify side effects such as increased heart rate, anxiety, or nervousness. To avoid these issues, it’s best to limit or avoid additional stimulant intake while taking phentermine.

Do I need a special diet or exercise plan while on Phentermine?

Phentermine should be used alongside a balanced, reduced-calorie diet that emphasizes nutrient-dense foods and supports long-term lifestyle modifications. For best results, phentermine should be part of a comprehensive weight loss plan that includes regular exercise and a focus on building sustainable, healthy habits.

References

Adipex-P (phentermine) [prescribing information]. Parsippany, NJ: Teva Pharmaceuticals USA Inc; March 2024.

Lexicomp Online. (n.d.). Phentermine: Drug Information. Retrieved from https://online.lexi.com/lco/action/doc/retrieve/docid/patch_f/7481

Allison DB, Gadde KM, Garvey WT, Peterson CA, Schwiers ML, Najarian T, Tam PY, Troupin B, Day WW. Controlled-release phentermine/topiramate in severely obese adults: a randomized controlled trial (EQUIP). Obesity (Silver Spring). 2012 Feb;20(2):330-42. doi: 10.1038/oby.2011.330. Epub 2011 Nov 3. PMID: 22051941; PMCID: PMC3270297.

Son JW, Kim S. Comprehensive Review of Current and Upcoming Anti-Obesity Drugs. Diabetes Metab J. 2020 Dec;44(6):802-818. doi: 10.4093/ dmj.2020.0258. Epub 2020 Dec 23. PMID: 33389955; PMCID: PMC7801751.

Kulak-Bejda A, Bejda G, Waszkiewicz N. Safety and efficacy of naltrexone for weight loss in adult patients - a systematic review. Arch Med Sci.2020 Sep 10;17(4):940-953. doi: 10.5114/aoms.2020.96908. PMID: 34336024; PMCID: PMC8314402.

Kučić N, Rački V, Šverko R, Vidović T, Grahovac I, Mršić-Pelčić J. Immunometabolic Modulatory Role of Naltrexone in BV-2 Microglia Cells. Int J Mol Sci. 2021 Aug 5;22(16):8429. doi: 10.3390/ijms22168429. PMID: 34445130; PMCID: PMC8395119.