Is it safe to prescribe Strattera (atomoxetine) for Attention Deficit Hyperactivity Disorder (ADHD), Remeron (mirtazapine) for appetite, sleep, and depression, and Buspar (buspirone) for anxiety to a patient taking cannabis?

Safety of Prescribing Strattera, Remeron, and Buspar to a Patient Taking Cannabis

Prescribing Strattera (atomoxetine) for ADHD, Remeron (mirtazapine) for appetite/sleep/depression, and Buspar (buspirone) for anxiety is generally safe for a patient taking cannabis, but requires careful monitoring for potential drug interactions and side effects.

Cannabis Interactions with Psychiatric Medications

Strattera (Atomoxetine) and Cannabis

• Atomoxetine is a selective norepinephrine reuptake inhibitor used for ADHD that works through inhibition of presynaptic norepinephrine reuptake in the prefrontal cortex 1
• Limited evidence exists regarding direct interactions between atomoxetine and cannabis
• One pilot study found that atomoxetine had limited utility in treating cannabis dependence and was associated with significant gastrointestinal adverse events in cannabis users 2
• No specific contraindications exist for concurrent use, but monitoring is essential

Remeron (Mirtazapine) and Cannabis

• Mirtazapine is often used for depression, sleep disturbances, and appetite stimulation
• No direct contraindications exist for concurrent use with cannabis
• Both substances may cause sedation, so patients should be warned about potential additive effects
• Mirtazapine's appetite-stimulating effects may complement cannabis use for patients needing weight gain

Buspar (Buspirone) and Cannabis

• Buspirone is recommended for anxiety with a starting dose of 15 mg daily and target dose of 20-30 mg daily 3
• A Cochrane review found buspirone was probably of little value in the treatment of cannabis dependence 4
• No significant adverse interactions have been reported between buspirone and cannabis

Potential Concerns and Monitoring

Cardiovascular Effects

• Cannabis may cause increased heart rate and blood pressure
• Atomoxetine is associated with statistically (but not clinically) significant increases in heart rate and blood pressure 1
• Monitor vital signs regularly, especially during the initial treatment period

Cognitive Effects

• THC in cannabis may acutely impair cognitive function 5
• Atomoxetine aims to improve cognitive function in ADHD
• These opposing effects should be discussed with the patient
• Consider evaluating cognitive function periodically

Gastrointestinal Effects

• High incidence (77%) of gastrointestinal adverse events (nausea, vomiting, dyspepsia, loose stools) was reported when atomoxetine was given to cannabis-dependent individuals 2
• Monitor for GI symptoms and adjust dosing if necessary

Risk of Cannabinoid Hyperemesis Syndrome

• Long-term cannabis use (>4 times per week for over a year) may lead to cannabinoid hyperemesis syndrome, characterized by cyclical vomiting episodes 6
• If the patient develops unexplained recurrent vomiting, consider this diagnosis
• Treatment focuses on cannabis cessation 6

Dosing and Administration Recommendations

Strattera (Atomoxetine)

• Start at the lowest effective dose and titrate slowly
• Monitor for gastrointestinal side effects, which may be more common in cannabis users
• Consider CYP2D6 metabolism status if available, as poor metabolizers have greater exposure to atomoxetine 1

Remeron (Mirtazapine)

• Start with low doses, especially if the patient is using cannabis in the evening (due to potential additive sedation)
• Take in the evening to maximize sleep benefits and minimize daytime sedation
• Monitor weight and appetite changes

Buspar (Buspirone)

• Start at 15 mg daily and titrate to 20-30 mg daily as recommended 3
• Divide doses to minimize side effects
• Monitor for dizziness, nausea, headache, and nervousness

Patient Education and Follow-up

• Advise the patient about potential additive sedative effects, especially with evening cannabis use
• Warn against driving while using cannabis, as cannabis users have twice the risk of motor vehicle accidents 6
• Schedule more frequent follow-ups initially to monitor for adverse effects
• Discuss the importance of consistent cannabis use patterns during medication adjustment periods
• Consider using standardized assessments at 4 and 8 weeks to evaluate treatment response 3

Conclusion

While there are no absolute contraindications to prescribing this medication combination to a cannabis user, close monitoring is essential, particularly for gastrointestinal effects with atomoxetine, sedation with mirtazapine, and overall treatment efficacy. The benefits of treating the patient's ADHD, depression/sleep/appetite issues, and anxiety likely outweigh the potential risks of drug interactions with cannabis.