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 unprescribed amphetamines, I recommend having a direct, non-judgmental conversation to understand the situation. Begin by saying, "I noticed your urine test showed amphetamines that I haven't prescribed. I'd like to discuss this to ensure we're providing you with the best care possible." Ask if they're taking medications prescribed by another provider, such as Adderall (mixed amphetamine salts), Vyvanse (lisdexamfetamine), or Dexedrine (dextroamphetamine), as these would explain the result. Be aware that certain medications like bupropion, ranitidine, or over-the-counter decongestants containing pseudoephedrine can cause false positives, as noted in a study on drug testing in children and adolescents 1. If recreational use is acknowledged, assess frequency, amount, and reasons for use without expressing judgment.

Key Considerations

• Discuss health risks including cardiovascular effects, dependency, and drug interactions, as individuals with stroke and known recreational drug use that may increase the risk of stroke, such as cocaine and amphetamines, should be counseled to discontinue use if not prescribed for medical indications 1.
• Consider the potential for false positives and the importance of knowing an individual's complete medical history, including prescribed medications, to interpret drug test results accurately 1.
• Document the conversation thoroughly in their medical record, including their explanation and your recommendations.

Approach to Care

The approach should maintain the therapeutic relationship while addressing potential health concerns and ensuring appropriate medical care. This is in line with recommendations for managing patients with substance use disorders, emphasizing the importance of a non-judgmental and supportive approach 1.

Recommendations

A direct and non-judgmental conversation is crucial in understanding the situation and providing the best care possible. This approach is supported by the most recent and highest quality studies on the management of substance use disorders, including those related to amphetamine addiction 1.

From the FDA Drug Label

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 determine if the result is accurate 2.

From the Research

Approaching the Patient

When discussing a positive urine tox screen for amphetamines with a patient, it's essential to consider the possibility of false-positive results. Several medications and substances can cause false-positive amphetamine screens, including:

• Bupropion, a commonly prescribed antidepressant and smoking cessation aid 3
• Atomoxetine, used to treat attention deficit hyperactivity disorder (ADHD) 4
• Imatinib, a medication used to treat certain types of cancer 5
• Other psychiatric and non-psychiatric drugs, such as labetalol, fenofibrate, and metformin 6

Key Points to Discuss

• The patient's medical history and current medications to identify potential causes of the false-positive result
• The limitations of immunoassay urine drug screens and the importance of confirmatory testing using mass spectrometry (MS) 6
• The possibility of cross-reactivity with other substances, which can lead to false-positive results 4, 5
• The need for further testing or evaluation to determine the cause of the positive screen

Considerations for Patient Communication

• Approach the conversation with empathy and an open mind, avoiding assumptions or accusations
• Explain the possibility of false-positive results and the factors that can contribute to them
• Discuss the next steps for evaluation and testing to determine the cause of the positive screen
• Emphasize the importance of accurate diagnosis and treatment, and the need for collaboration between the patient and healthcare provider to achieve this goal 3, 6