What to say to a patient with a positive urine toxicology (tox) screen for amphetamines not prescribed by the current physician?

From the Guidelines

When addressing a patient with a positive urine toxicology for amphetamines not prescribed by you, approach the conversation with a non-judgmental, direct manner, and consider referral to addiction specialists if needed, as evidenced by the efficacy of contingency management and community reinforcement approach in treating amphetamine addiction 1.

Key Considerations

• Begin by saying, "I'd like to discuss your recent urine test results, which showed positive for amphetamines that I haven't prescribed for you."
• Ask open-ended questions about their medication use, such as "Can you tell me about any medications you're taking that I might not be aware of?"
• Remember that false positives can occur with certain medications like bupropion, ranitidine, or over-the-counter cold medications containing pseudoephedrine.
• If the patient acknowledges non-prescribed amphetamine use, assess for substance use disorder using screening tools and discuss health risks associated with non-prescribed stimulant use, including cardiovascular effects, psychiatric symptoms, and potential for dependence.

Treatment Options

• Contingency management (CM) has shown efficacy in treating amphetamine addiction, with a number needed to treat (NNT) of 5.2 for abstinence at 12 weeks of treatment 1.
• Community reinforcement approach (CRA) has also shown promise, particularly when combined with CM, with an NNT of 2.1 for abstinence at 12 weeks of treatment 1.
• Referral to addiction specialists may be necessary, as they can provide guidance on the most effective treatment approaches and support the patient's recovery.

Documentation and Follow-up

• Clearly document the conversation, including the patient's explanation and your recommendations.
• Follow up with the patient to monitor their progress and adjust the treatment plan as needed.
• Consider the potential benefits of reducing punishment and adopting positive reinforcement for people with substance use disorders, as suggested by recent experimental data 1.

From the FDA Drug Label

1. 7 Drug-Laboratory Test Interactions False-positive urine immunoassay screening tests for amphetamines have been reported in patients taking bupropion. This is due to lack of specificity of some screening tests. False-positive test results may result even following discontinuation of bupropion therapy Confirmatory tests, such as gas chromatography/mass spectrometry, will distinguish bupropion from amphetamines.

You can say to the patient: Your urine test shows a positive result for amphetamines, but this could be a false positive due to the bupropion you are taking. It is recommended to conduct confirmatory tests, such as gas chromatography/mass spectrometry, to distinguish between bupropion and amphetamines 2.

From the Research

Approaching a Patient with a Positive Urine Tox Screen for Amphetamines

When a patient tests positive for amphetamines on a urine tox screen and the medication was not prescribed by you, it's essential to consider several factors before making any conclusions.

• False-Positive Results: There are instances where certain medications can lead to false-positive results for amphetamines on urine drug screens. For example, atomoxetine, a medication used to treat Attention Deficit Hyperactivity Disorder (ADHD), has been reported to cause false-positive results for amphetamines in urine tests 3. Similarly, imatinib, a drug used in the treatment of certain cancers, has also been implicated in false-positive amphetamine results 4.
• Medication Interference: Various commonly prescribed medications can interfere with urine drug screens, leading to false-positive results. A study identified several classes of medications, including antihistamines, antidepressants, and antipsychotics, that can cause false-positive results for different substances, including amphetamines 5.
• Confirmation Testing: Given the potential for false-positive results, it's crucial to confirm any positive urine tox screen with a more specific test, such as gas chromatography-mass spectrometry (GC-MS), before taking any action 3, 5, 4.
• Patient History and Denial of Use: If a patient denies any illicit drug use and has a history of taking medications that could potentially cause false-positive results, this should be taken into consideration. The patient's denial, combined with the potential for false positives, warrants further investigation rather than immediate judgment 3, 4.
• Safety Profiles of Prescribed Medications: Understanding the safety profiles of medications like methylphenidate, atomoxetine, and amphetamine is also important. These medications, used in the treatment of ADHD, have their own set of potential side effects and risks, as highlighted in a pharmacovigilance analysis 6.

Next Steps

• Confirmatory Testing: Order a confirmatory test, such as GC-MS, to verify the presence of amphetamines.
• Review Medication List: Review the patient's current medication list to identify any potential causes of false-positive results.
• Patient Interview: Conduct a thorough interview with the patient to understand their medication adherence, any recent changes in medications, and to reaffirm their denial of illicit drug use.
• Collaboration with Other Healthcare Providers: If necessary, collaborate with other healthcare providers who may have prescribed medications that could interfere with urine drug screens.