FDA SIDE EFFECTS UPDATE: Antidepressants, Stimulants May Interfere With Parkinson’s Test

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<p>Welcome to the FDA Side Effects Update. This series is designed to keep you informed about the latest safety advisories and newly documented side effects of your medications. In this installment, we’re highlighting safety updates regarding DATSCAN, a diagnostic tracer agent used in imaging procedures to help diagnose suspected <a href="https://medlineplus.gov/parkinsonsdisease.html">Parkinson’s Disease</a> (PD) and suspected <a href="https://medlineplus.gov/lewybodydementia.html">dementia with Lewy bodies</a> (DLB). We’re also highlighting safety updates for three ADHD drugs that may interfere with DATSCAN image interpretation: Adderall XR, Mydayis, and Vyvanse.</p>
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<p>This report is prepared using the most recent information posted in the<a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm"> SrLC database</a>. It highlights recent safety labeling changes. It includes only newly reported side effects and safety information; additional side effects and warnings will appear on the drug label. Not all recent changes to the SrLC database or the label may be listed here. For all changes and the complete list of warnings and side effects, please click on the drug label link.</p>
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<p>Each of the items (approval and update dates, drug names, etc.) contained in this report are obtained from the SrLC. The side effects and medication descriptions are simplified and made clearer, if needed. Sometimes, additional sources, like a medical dictionary, may be used to translate technical medical phrases. Other sources (company news, FDA press releases, etc.) may be used to learn about some label changes.</p>
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<h2 class="wp-block-heading">Updated Warning for DATSCAN Diagnostic Agent</h2>
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<h3 class="wp-block-heading">DATSCAN (ioflupane I 123 injection), for intravenous use</h3>
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<p><strong>Initial FDA Approval</strong>: 2011<br><strong>Side Effect Update Date</strong>: April 15, 2026<br><strong>Medication Description</strong>: Radioactive imaging agent used to visualize dopamine transporters, proteins found on dopamine-producing neurons in the brain. DATSCAN helps doctors diagnose adults with suspected Parkinsonian syndromes, including Parkinson's disease and Dementia with Lewy bodies. Because dopamine activity is reduced in these conditions, the scan can reveal characteristic patterns associated with these disorders.</p>
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<p>Between three and six hours after DATSCAN is administered intravenously, the brain is scanned with <a href="https://my.clevelandclinic.org/health/diagnostics/spect-scan">single-photon emission computed tomography</a> (SPECT) equipment to visualize the presence and pattern of dopamine transporters, which may help to make a diagnosis or rule out a diagnosis. For example, it can be used to distinguish <a href="https://medlineplus.gov/ency/article/000762.htm">essential tremor</a>, an involuntary shaking movement often affecting the hands, from Parkinson’s Disease.</p>
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<p><strong>Updated Side Effects/Safety Information:</strong> A new warning that the antidepressants venlafaxine (brand name, Effexor ) and desvenlafaxine (Pristiq) may affect DATSCAN brain imaging interpretation. These medications should be discontinued for at least 5 biological half-lives (approximately 5 to 11 hours, depending on the formulation) before administering DATSCAN.<br><strong>FDA Safety Announcement</strong>:<a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2217"> DATSCAN Safety Label Update</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/022454s017lbl.pdf">Revised Drug Label<br></a>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.<br><strong>Essential Extras</strong>: Additional medications listed on the DATSCAN label that may interfere with scan interpretation include amoxapine, amphetamine, armodafinil, benztropine, bupropion, buspirone, cocaine, mazindol, methamphetamine, methylphenidate, modafinil, norephedrine, phentermine, selegiline, sertraline, citalopram, paroxetine, venlafaxine, and desvenlafaxine.</p>
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<p>The DATSCAN is not a stand-alone diagnostic test; it is meant to be used alongside a clinician's evaluation. Other laboratory tests sometimes used to help with diagnosis include blood tests and MRI procedures.</p>
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<h2 class="wp-block-heading">Updated Drug Interaction Warnings for ADHD Drugs</h2>
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<h3 class="wp-block-heading">Adderall XR 10 (mixed salts of a single-entity amphetamine product) extended-release tablets</h3>
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<p><strong>Initial FDA Approval:</strong> 2001<br><strong>Side Effect Update Date</strong>: April 23, 2026<br><strong>Medication Description</strong>: Treats Attention Deficit Hyperactivity Disorder (ADHD) in adults and pediatric patients 6 years and older. <br><strong>Updated Side Effects/Safety Information</strong>: A new warning that Adderall XR can interfere with dopamine transporter visualization test results (DATSCAN), a test used to help diagnose conditions like Parkinson’s disease (PD) or dementia with Lewy bodies (DLB). Since Adderall XR affects dopamine transporters in the brain, taking it with DATSCAN can potentially lead to a false-positive diagnosis. Patients are advised to withhold the medication prior to the laboratory test.<br><strong>FDA Safety Announcement:</strong><a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=733"> Adderall XR FDA Safety Label Change</a> and<a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/021303s040,021977s052,208510s009,022063s007lbl.pdf"> Revised Drug Label<br></a>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.</p>
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<h3 class="wp-block-heading">Mydayis (mixed salts of a single-entity amphetamine product) extended-release capsules</h3>
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<p><strong>Initial FDA Approval</strong>: 2001<br><strong>Medication Description</strong>: Treats Attention Deficit Hyperactivity Disorder (ADHD) in patients 13 years and older. <br><strong>Updated Side Effects/Safety Information</strong>: A new warning that Mydayis can interfere with dopamine transporter visualization test results (DATSCAN), a test used to help diagnose conditions like Parkinson’s disease (PD) or dementia with Lewy bodies (DLB). Since Mydayis affects dopamine transporters in the brain, taking it with DATSCAN can potentially lead to a false-positive diagnosis. Patients are advised to withhold the medication prior to the laboratory test.<br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=2080">Mydayis Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/021303s040,021977s052,208510s009,022063s007lbl.pdf">Revised Drug Label</a><br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.</p>
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<h3 class="wp-block-heading">Vyvanse (lisdexamfetamine dimesylate) capsules and chewable tablets</h3>
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<p><strong>Initial FDA Approval</strong>: capsules: 2007, chewable tablets: 2017<br><strong>Side Effect Update Date</strong>: April 23, 2026<br><strong>Medication Description</strong>: Treats Attention Deficit Hyperactivity Disorder (ADHD) in adults and pediatric patients 6 years and older; treats moderate to severe binge eating disorder in adults. <br><strong>Updated Side Effects/Safety Information</strong>: A new warning that Vyvanse can interfere with dopamine transporter visualization test results (DATSCAN), a test used to help diagnose conditions like Parkinson’s disease (PD) or dementia with Lewy bodies (DLB). Since Vyvanse affects dopamine transporters in the brain, taking it with DATSCAN can potentially lead to a false-positive diagnosis. Patients are advised to withhold the medication prior to the laboratory test.<br><strong>FDA Safety Announcement</strong>: <a href="https://www.accessdata.fda.gov/scripts/cder/safetylabelingchanges/index.cfm?event=searchdetail.page&DrugNameID=472">Vyvanse FDA Safety Label Change</a> and <a href="https://www.accessdata.fda.gov/drugsatfda_docs/label/2026/021303s040,021977s052,208510s009,022063s007lbl.pdf">Revised Drug Label</a><br>The revised drug label contains a complete list of FDA-approved indications, side effects, warnings, and more.</p>
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