THC and CBD May Increase Methylphenidate Levels Through a Shared Liver Enzyme
Pharmacokinetic modeling predicted that THC from smoking cannabis could increase methylphenidate (Ritalin) blood levels by 34%, while prescription CBD doses could increase it by up to 94%, through inhibition of the CES1 liver enzyme.
Quick Facts
What This Study Found
Both THC and CBD reversibly inhibited the CES1 enzyme that metabolizes methylphenidate. Static models predicted THC from a cannabis cigarette could increase MPH exposure by 34%. Multiple daily CBD doses (10 mg/kg twice daily) could increase MPH exposure by up to 55% and peak concentration by 45%.
Key Numbers
THC unbound Ki: 0.031 mcM. CBD unbound Ki: 0.091 mcM. Static model: 34% MPH increase from smoked THC, 94% increase from prescription CBD. PBPK model: up to 55% AUC and 45% Cmax increase with multiple CBD doses. Single CBD doses showed no significant interaction.
How They Did This
In vitro inhibition studies using human liver S9 fractions to measure THC and CBD inhibition of CES1-mediated methylphenidate hydrolysis. Results were incorporated into static and physiologically-based pharmacokinetic (PBPK) models to predict clinical interaction significance.
Why This Research Matters
Many people with ADHD use cannabis, and CBD is increasingly being explored for ADHD symptoms. If cannabinoids increase methylphenidate blood levels, this could lead to unexpected side effects or altered medication efficacy in a large patient population.
The Bigger Picture
This is the first study to identify CES1 as a mechanism for cannabinoid-methylphenidate interactions. Given overlapping use of these substances (especially in adolescents and young adults), even mild pharmacokinetic interactions could have clinical relevance at the population level.
What This Study Doesn't Tell Us
Predictions are based on in vitro data and mathematical modeling, not clinical studies in humans. Actual interactions could be larger or smaller depending on individual variation, food effects, and other concurrent medications. The models assume specific cannabinoid exposure levels.
Questions This Raises
- ?Would a clinical pharmacokinetic study confirm the predicted interaction magnitudes?
- ?Should ADHD patients on methylphenidate be cautioned about cannabis use?
- ?Is CES1 inhibition also relevant for other ester-containing medications?
Trust & Context
- Key Stat:
- Predicted 34% MPH increase from THC, up to 55% from multiple CBD doses
- Evidence Grade:
- Preliminary: in vitro and modeling study that has not been confirmed in human clinical trials.
- Study Age:
- Published in 2022.
- Original Title:
- Prediction of Carboxylesterase 1-mediated In Vivo Drug Interaction between Methylphenidate and Cannabinoids using Static and Physiologically Based Pharmacokinetic Models.
- Published In:
- Drug metabolism and disposition: the biological fate of chemicals, 50(7), 968-979 (2022)
- Authors:
- Qian, Yuli(2), Markowitz, John S(2)
- Database ID:
- RTHC-04155
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Can cannabis affect ADHD medication?
This modeling study predicted that THC from cannabis smoking could increase methylphenidate blood levels by about 34%, and high-dose prescription CBD by more than 50%. These predictions have not been confirmed in human studies but suggest a potential interaction worth monitoring.
Is it safe to take CBD with Ritalin?
This study predicts a mild interaction, especially with repeated high-dose CBD. Single doses of CBD are unlikely to cause significant changes. Until human studies confirm these predictions, patients should inform their prescribers about any CBD or cannabis use.
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Cite This Study
https://rethinkthc.com/research/RTHC-04155APA
Qian, Yuli; Markowitz, John S. (2022). Prediction of Carboxylesterase 1-mediated In Vivo Drug Interaction between Methylphenidate and Cannabinoids using Static and Physiologically Based Pharmacokinetic Models.. Drug metabolism and disposition: the biological fate of chemicals, 50(7), 968-979. https://doi.org/10.1124/dmd.121.000823
MLA
Qian, Yuli, et al. "Prediction of Carboxylesterase 1-mediated In Vivo Drug Interaction between Methylphenidate and Cannabinoids using Static and Physiologically Based Pharmacokinetic Models.." Drug metabolism and disposition: the biological fate of chemicals, 2022. https://doi.org/10.1124/dmd.121.000823
RethinkTHC
RethinkTHC Research Database. "Prediction of Carboxylesterase 1-mediated In Vivo Drug Inter..." RTHC-04155. Retrieved from https://rethinkthc.com/research/qian-2022-prediction-of-carboxylesterase-1mediated
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.