Phentermine Vs. Wellbutrin: Drug Comparison

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​.

Wellbutrin SR^® (bupropion sustained-release) is an antidepressant that works by inhibiting the reuptake of norepinephrine and dopamine in the brain, which helps improve mood and reduce symptoms of depression. Its FDA-approved indication includes the treatment of major depressive disorder (MDD). Off-label uses may include treating anxiety and attention-deficit hyperactivity disorder (ADHD). Wellbutrin SR is available in sustained-release tablet form. Common side effects include insomnia, dry mouth, constipation, and headache, and it has a boxed warning for an increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults.

Sympathomimetic amine anorectic

Aminoketone antidepressant

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)

Wellbutrin SR (bupropion hydrochloride) is indicated:

• For the treatment of major depressive disorder (MDD)

• Typically taken orally once daily

• Comes in 37.5 mg tablets

• Typically taken orally twice daily

• Comes in 100 mg, 150 mg, and 200 mg tablets

Adverse events have been reported in the following systems:

• Cardiovascular

• Central nervous system

• Gastrointestinal

• Allergic

• Endocrine

Most common adverse reactions (incidence ≥5% and ≥2% more than placebo rate) are:

• Headache

• Dry mouth

• Nausea

• Insomnia

• Dizziness

• Inflammation of the throat

• Constipation

• Agitation

• Anxiety

• Abdominal pain

• Ringing in the ears

• Tremor

• Fluttering heartbeat

• Muscle pain

• Sweating

• Rash

• Anorexia

• 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

• Seizure disorder

• Current or prior diagnosis of bulimia or anorexia nervosa

• Abrupt discontinuation of alcohol, benzodiazepines, barbiturates, antiepileptic drugs

• Monoamine oxidase inhibitors (MAOIs)

• Known hypersensitivity to bupropion or other ingredients of Wellbutrin SR.

• Drug interactions: CYP2B6 inducers, drugs metabolized by CYP2D6, digoxin, drugs that lower seizure threshold, dopaminergic drugs (levodopa and amantadine), MAOIs

• Drug-laboratory test interactions: Wellbutrin SR can cause false-positive urine test results for amphetamines

• 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

• Neuropsychiatric adverse events during smoking cessation

• Seizure risk

• High blood pressure

• Activation of mania/hypomania

• Psychosis and other neuropsychiatric reactions

• Angle-closure glaucoma

WARNING: SUICIDAL THOUGHTS AND BEHAVIORS

Increased risk of suicidal thinking and behavior in children, adolescents and young adults taking antidepressants.

Monitor for worsening and emergence of suicidal thoughts and behaviors.

*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.

*This information is from the label for brand name Wellbutrin SR^®. See the Full Prescribing Information for more complete information. Bupropion, the active ingredient in Wellbutrin XL, may also be the active ingredient in other medications, and this information may not be accurate for all medications that include the active ingredient bupropion.