Can a 26-year-old patient taking Concerta (methylphenidate) for Attention Deficit Hyperactivity Disorder (ADHD) as needed (PRN) safely take phentermine for weight loss, given a refusal to use Glucagon-Like Peptide-1 (GLP-1) receptor agonists due to needle phobia?

From the Guidelines

I would not recommend combining phentermine with Concerta (methylphenidate) due to significant safety concerns, as both medications are stimulants that can increase heart rate and blood pressure, potentially causing dangerous cardiovascular effects when used together. For this 26-year-old patient with ADHD who wants weight loss support but refuses injectable GLP-1 medications due to needle phobia, I would suggest considering oral alternatives like naltrexone-bupropion (Contrave) or orlistat (Xenical/Alli) 1. Contrave works by affecting hunger and reward centers in the brain, while orlistat reduces fat absorption. Some key points to consider:

• Phentermine is classified as a schedule IV-controlled substance based on concerns for abuse and dependence 1
• The use of phentermine for individuals with obesity or overweight with weight-related complications is conditionally recommended due to the lack of high-quality data for the efficacy and safety of long-term monotherapy 1
• Non-pharmacological approaches should also be emphasized, including structured dietary changes, regular physical activity, behavioral therapy, and possibly working with a registered dietitian Another option is topiramate, either alone or combined with phentermine (Qsymia), but this would require discontinuing the Concerta first and discussing with his psychiatrist. The patient should understand that combining two stimulants (Concerta and phentermine) significantly increases risks of insomnia, anxiety, elevated blood pressure, and cardiac issues, making this combination inadvisable.

From the FDA Drug Label

5.1 Coadministration with Other Drug Products for Weight Loss Phentermine is indicated only as short-term (a few weeks) monotherapy for the management of exogenous obesity The safety and efficacy of combination therapy with phentermine and any other drug products for weight loss including prescribed drugs, over-the-counter preparations, and herbal products, or serotonergic agents such as selective serotonin reuptake inhibitors (e.g., fluoxetine, sertraline, fluvoxamine, paroxetine), have not been established. Therefore, coadministration of phentermine and these drug products is not recommended.

The patient is taking Concerta for ADHD, which is a stimulant medication.

• Key consideration: The safety and efficacy of combination therapy with phentermine and other stimulant medications like Concerta have not been established.
• Clinical decision: It is not recommended to coadminister phentermine with Concerta due to the lack of established safety and efficacy of this combination. 2

From the Research

Potential Interactions between Concerta and Phentermine

• The patient is taking Concerta (methylphenidate) for ADHD and wants to take phentermine for weight loss 3, 4.
• There is limited research on the specific interaction between Concerta and phentermine, but both drugs are central nervous system stimulants and may increase the risk of adverse effects such as anxiety, insomnia, and increased heart rate and blood pressure 5, 6.
• A study on the safety and effectiveness of longer-term phentermine use found that patients who used phentermine for more than 12 months experienced more weight loss without an increased risk of cardiovascular disease or death 6.

Considerations for Phentermine Use

• Phentermine is an amphetamine derivative with significant appetite-suppressing properties, but its long-term use may be associated with severe cardiovascular side effects, abuse, and dependence 5.
• A review of phentermine in the modern era of obesity pharmacotherapy suggests that it may still have a role in treatment, but there is limited rigorous research to support its efficacy and safety in long-term treatment 7.
• Clinicians may consider using phentermine long-term in selected patients, but this should be done with caution and careful monitoring of potential adverse effects 7.

Alternative Options for Weight Loss

• The patient is needle-phobic and does not want to use GLP-1 medications, which are commonly used for weight loss 6, 7.
• Other options for weight loss may include lifestyle modifications such as diet and exercise, or other medications that do not have the same potential interactions with Concerta 4, 7.
• It is essential to discuss the potential risks and benefits of different weight loss options with the patient and determine the best course of treatment based on their individual needs and medical history 5, 3, 6, 4, 7.