Why is Wellbutpring (buproparmine) contraindicated with phentermine?

From the Guidelines

Wellbutrin (bupropion) is contraindicated with phentermine due to the increased risk of adverse cardiovascular effects, as both medications can raise blood pressure and heart rate, potentially leading to serious complications, as noted in the AGA clinical practice guideline on pharmacological interventions for adults with obesity 1. The primary concern with combining these medications is the potential for excessive sympathetic stimulation, which can lead to increased heart rate, blood pressure elevations, and other cardiovascular complications. Phentermine, a sympathomimetic amine, works by stimulating the central nervous system to suppress appetite, while bupropion, an antidepressant, can also increase sympathetic activity, particularly at higher doses. When used together, they may cause additive or synergistic effects, leading to increased cardiovascular risk. Some key points to consider when evaluating the safety of combining these medications include:

• The potential for increased blood pressure and heart rate, which can be problematic for patients with pre-existing cardiovascular disease or those at high risk for cardiovascular complications 1.
• The lack of high-quality data on the safety and efficacy of long-term use of phentermine, particularly in combination with other medications that may increase cardiovascular risk 1.
• The importance of careful patient selection, monitoring, and documentation when using phentermine, particularly in off-label fashion or in combination with other medications 1. Given the potential risks and limited data on the safety and efficacy of combining Wellbutrin and phentermine, it is generally recommended to avoid using these medications together, and instead consider alternative weight management strategies or sequential therapy options. If you're currently taking one of these medications and considering the other, it's essential to consult with your healthcare provider to discuss the potential risks and benefits and determine the best course of treatment for your individual needs.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Overview of Phentermine and Bupropion Interaction

• Phentermine is an amphetamine derivative with appetite-suppressing properties, used for short-term management of obesity 2.
• Bupropion is an antidepressant that can be used in combination with naltrexone for weight loss 3, 4.

Potential Drug-Drug Interactions

• The combination of phentermine and bupropion may increase the risk of adverse drug reactions, such as seizures, due to their synergistic effects on the central nervous system 4.
• There is limited research on the specific interaction between phentermine and bupropion, but studies suggest that combining these medications may increase the risk of adverse events, such as anxiety, depression, and insomnia 5, 4.

Contraindications and Warnings

• The use of phentermine with other medications that increase the risk of seizures, such as bupropion, is contraindicated due to the potential for increased risk of seizures 4.
• Patients taking phentermine and bupropion concurrently should be closely monitored for signs of adverse reactions, such as changes in mood, behavior, or cognitive function 5, 4.

Clinical Implications

• Healthcare providers should exercise caution when prescribing phentermine and bupropion together, and carefully weigh the potential benefits against the risks of adverse reactions 2, 4.
• Patients should be informed of the potential risks and benefits of combining these medications and should be closely monitored for signs of adverse reactions 5, 4.