Diethylpropion Vs. Phentermine: Drug Comparison

Diethylpropion is a drug used as an appetite suppressant for short-term weight loss in patients with obesity. It works by stimulating the central nervous system, increasing heart rate, and decreasing appetite, and helping with weight reduction when used alongside diet and exercise. Its FDA-approved indication is for short-term use (a few weeks) in the management of obesity in patients who have not responded to appropriate weight reducing regimen (diet and/or exercise) alone. Diethylpropion is available in immediate-release tablets and controlled-release tablets. Common side effects include dry mouth, insomnia, increased heart rate, and nervousness, and it carries a risk of dependence and abuse as a Schedule IV controlled substance. It should be used cautiously with other stimulants and in individuals with cardiovascular issues.

Phentermine is the active ingredient in brand-name medications including Adipex-P^®. The information below is about brand name Adipex-P. According to the FDA, “Generic medicines use the same active ingredients as brand-name medicines and work the same way, so they have the same risks and benefits as the brand-name medicines.”

Adipex-P (phentermine hydrochloride) is a prescription medication used as a short-term adjunct to weight loss in patients with obesity. It works as an appetite suppressant by stimulating the central nervous system, which increases heart rate and blood pressure while reducing hunger. Adipex-P is typically prescribed alongside a reduced-calorie diet and exercise regimen to enhance weight loss efforts. Common side effects include increased heart rate, dry mouth, insomnia, and nervousness. It is important to note that Adipex-P is intended for short-term use due to the potential for dependence and other adverse effects​.

Sympathomimetic amine

Sympathomimetic amine anorectic

Diethylpropion is indicated:

• In the management of exogenous obesity as a short-term adjunct (a few weeks) in a regimen of weight reduction based on caloric restriction in patients with an initial body mass index (BMI) of 30 kg/m² or higher and who have not responded to appropriate weight reducing regimen (diet and/or exercise) alone

Adipex-P (phentermine hydrochloride) is indicated:

• As a short-term adjunct (a few weeks) in a regimen of weight reduction based on exercise, behavioral modification and caloric restriction in the management of exogenous obesity for patients with an initial body mass index greater than or equal to 30 kg/m², or greater than or equal to 27 kg/m² in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia)

• Typically taken orally three times daily

• Comes in 25 mg tablets

• Typically taken orally once daily

• Comes in 37.5 mg tablets

Adverse reactions have been reported in the following systems:

• Cardiovascular

• Central nervous system

• Gastrointestinal

• Allergic

• Endocrine

• Hematopoietic system

• Other

Adverse events have been reported in the following systems:

• Cardiovascular

• Central nervous system

• Gastrointestinal

• Allergic

• Endocrine

• Pulmonary hypertension, advanced arteriosclerosis, hyperthyroidism, known hypersensitivity or idiosyncrasy to the sympathomimetic amines, glaucoma, severe hypertension

• Agitated states

• Patients with a history of drug abuse

• Use in combination with other anorectic agents is contraindicated

• During or within 14 days following the administration of monoamine oxidase inhibitors

• Drug interactions: MAO inhibitors, other anorectic agents, diabetes drugs

• History of cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, congestive heart failure, uncontrolled hypertension)

• During or within 14 days following the administration of monoamine oxidase inhibitors

• Hyperthyroidism

• Glaucoma

• Agitated states

• History of drug abuse

• Pregnancy

• Nursing

• Known hypersensitivity, or idiosyncrasy to the sympathomimetic amines

• Drug interactions: Monoamine oxidase inhibitors, alcohol, insulin and oral hypoglycemics, adrenergic neuron blocking drugs

• Should not be used in combination with other anorectic agents, including prescribed drugs, over-the-counter preparations, and herbal products

• The onset or aggravation of exertional dyspnea, or unexplained symptoms of angina pectoris, syncope, or lower extremity edema suggest the possibility of occurrence of pulmonary hypertension

• Valvular heart disease associated with the use of some anorectic agents such as fenfluramine and dexfenfluramine has been reported

• Treatment should be continued only if the patient has satisfactory weight loss within the first 4 weeks of treatment

• Prolonged use of diethylpropion hydrochloride may induce dependence with withdrawal syndrome on cessation of therapy

• When central nervous system active agents are used, consideration must always be given to the possibility of adverse interactions with alcohol

• Caution is to be exercised in prescribing for patients with hypertension or with symptomatic cardiovascular disease, including arrhythmias

• Reports suggest that diethylpropion hydrochloride may increase convulsions in some epileptics

• Pregnancy: This drug should be used during pregnancy only if clearly needed

• Breastfeeding: Caution should be exercised when administered to a nursing woman

• Coadministration with other drugs for weight loss is not recommended

• Rare cases of primary pulmonary hypertension have been reported

• Rare cases of serious regurgitant cardiac valvular disease have been reported

• Tolerance to the anorectic effect usually develops within a few weeks

• Adipex-P may impair the ability of the patient to engage in potentially hazardous activities such as operating machinery or driving a motor vehicle

• Risk of abuse and dependence

• Concomitant alcohol use may result in an adverse drug reaction

• Use caution in patients with even mild high blood pressure

• A reduction in dose of insulin or oral hypoglycemic medication may be required in some patients

• Breastfeeding: Discontinue drug or nursing taking into consideration importance of drug to mother

*This information is from the diethylpropion hydrochloride label used by Chartwell RX, LLC. See the Full Prescribing Information for more complete information. Diethylpropion may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient diethylpropion.

*This information is from the label for brand name Adipex-P^®. See the Full Prescribing Information for more complete information. Phentermine, the active ingredient in Adipex-P, may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient phentermine.