Phendimetrazine Vs. Phentermine: Drug Comparison

Phendimetrazine is a drug used as an appetite suppressant for short-term treatment of obesity. It works by stimulating the central nervous system (CNS), increasing heart rate and blood pressure, and reducing appetite, helping individuals to consume fewer calories. Its FDA-approved indication is for short-term use in conjunction with a reduced-calorie diet in adults with overweight or obesity. Phendimetrazine is available in both immediate-release tablets and extended-release capsules. Common side effects include increased heart rate, dry mouth, insomnia, and nervousness. It has a potential for abuse and dependence, especially in individuals with a history of substance abuse.

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

Phendimetrazine 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 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) 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 once daily

• Comes in 105 mg tablets

• Typically taken orally once daily

• Comes in 37.5 mg tablets

Adverse reactions include:

• Primary pulmonary hypertension

• Valvular heart disease

• Effect on the ability to engage in potentially hazardous tasks

• Withdrawal effects following prolonged high dosage administration

Adverse reactions have also been reported in the following systems:

• Cardiovascular

• Central nervous system

• Gastrointestinal

• Genitourinary

Adverse events have been reported in the following systems:

• Cardiovascular

• Central nervous system

• Gastrointestinal

• Allergic

• Endocrine

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

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

• Hyperthyroidism

• Glaucoma

• Agitated states

• History of drug abuse

• Pregnancy

• Nursing

• Use in combination with other anorectic agents or CNS stimulants

• Known hypersensitivity or idiosyncratic reactions to sympathomimetics

• Drug interactions: MAO inhibitors, alcohol, insulin and oral hypoglycemic medications, adrenergic neuron blocking 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

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

• In a case-control epidemiological study, the use of anorectic agents, including phendimetrazine tartrate, was associated with an increased risk of developing pulmonary hypertension, a rare, but often fatal disorder

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

• Phendimetrazine tartrate is not recommended for patients who used any anorectic agents within the prior year

• Caution is to be exercised in prescribing phendimetrazine tartrate for patients with even mild hypertension

• Insulin or oral hypoglycemic medication requirements in diabetes mellitus may be altered in association with the use of phendimetrazine and the concomitant dietary regimen

• Phendimetrazine may decrease the hypotensive effect of guanethidine

• The least amount feasible should be prescribed or dispensed at one time in order to minimize the possibility of overdosage

• Studies with phendimetrazine tartrate sustained release have not been performed to evaluate carcinogenic potential, mutagenic potential or effects on fertility

• Pregnancy: If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus

• Breastfeeding: Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother

• 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 phendimetrazine tartrate label used by Acertis Pharmaceuticals, LLC. See the Full Prescribing Information for more complete information. Phendimetrazine may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient phendimetrazine.

*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.