Cannabis products can interfere with many common medications through liver enzyme interactions
THC, CBD, and CBN inhibit multiple drug-metabolizing enzymes, meaning cannabis products could alter the effectiveness or toxicity of many commonly prescribed medications.
Quick Facts
What This Study Found
CYP2C9, CYP1A1/2, and CYP1B1 are likely inhibited by all three major cannabinoids (THC, CBD, CBN). CYP2D6, CYP2C19, CYP2B6, and CYP2J2 are inhibited by THC and CBD. CYP3A4/5/7 is potentially inhibited by CBD alone. Clinical evidence supports CBD inhibition of CYP2C19 and various cannabis products inhibiting CYP2C9.
Key Numbers
THC, CBD, and CBN all inhibit CYP2C9, CYP1A1/2, CYP1B1. THC and CBD inhibit CYP2D6, CYP2C19, CYP2B6, CYP2J2. CBD inhibits CYP3A4/5/7, UGT1A9, and potentially CES1. Cannabis smoking induces CYP1A2.
How They Did This
Systematic literature search of Google Scholar and PubMed through March 2019 for in vitro and clinical studies of cannabis drug interaction potential. In vitro inhibition parameters were compared to physiologically achievable cannabinoid concentrations.
Why This Research Matters
As medical cannabis and CBD products proliferate, patients often take them alongside prescription medications. This review identifies specific enzyme pathways at risk, helping clinicians anticipate dangerous interactions.
The Bigger Picture
The explosion of CBD products means millions of people are unknowingly combining cannabinoids with medications metabolized by the same enzymes. Warfarin (CYP2C9), clopidogrel (CYP2C19), and many psychiatric drugs (CYP2D6) could all be affected.
What This Study Doesn't Tell Us
Many findings are based on in vitro data that may not reflect real-world clinical significance. Clinical drug interaction studies with cannabis are still limited. Most in vivo data involves smoked cannabis or CBD specifically.
Questions This Raises
- ?At what doses do cannabis-drug interactions become clinically significant?
- ?Should patients on blood thinners avoid cannabis entirely?
- ?Do different consumption methods change the interaction profile?
Trust & Context
- Key Stat:
- THC, CBD, and CBN all inhibit CYP2C9, CYP1A1/2, and CYP1B1
- Evidence Grade:
- Moderate: systematic review combining in vitro and limited clinical data, providing comprehensive but partly theoretical interaction profiles.
- Study Age:
- Published in 2019.
- Original Title:
- The Potential for Pharmacokinetic Interactions Between Cannabis Products and Conventional Medications.
- Published In:
- Journal of clinical psychopharmacology, 39(5), 462-471 (2019)
- Authors:
- Qian, Yuli(2), Gurley, Bill J(2), Markowitz, John S(2)
- Database ID:
- RTHC-02243
Evidence Hierarchy
Analyzes all available research on a topic using a structured method.
What do these levels mean? →Frequently Asked Questions
Which medications are most at risk?
Medications metabolized primarily by CYP2C19 (e.g., clopidogrel, some antidepressants), CYP2C9 (e.g., warfarin), and CYP1A2 (e.g., theophylline, some antipsychotics) are at highest theoretical risk of altered levels when combined with cannabis.
Does this apply to CBD products sold in stores?
Potentially, yes. CBD inhibits several of the same enzymes as THC. Anyone taking prescription medications alongside CBD products may be at risk for altered drug levels.
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Cite This Study
https://rethinkthc.com/research/RTHC-02243APA
Qian, Yuli; Gurley, Bill J; Markowitz, John S. (2019). The Potential for Pharmacokinetic Interactions Between Cannabis Products and Conventional Medications.. Journal of clinical psychopharmacology, 39(5), 462-471. https://doi.org/10.1097/JCP.0000000000001089
MLA
Qian, Yuli, et al. "The Potential for Pharmacokinetic Interactions Between Cannabis Products and Conventional Medications.." Journal of clinical psychopharmacology, 2019. https://doi.org/10.1097/JCP.0000000000001089
RethinkTHC
RethinkTHC Research Database. "The Potential for Pharmacokinetic Interactions Between Canna..." RTHC-02243. Retrieved from https://rethinkthc.com/research/qian-2019-the-potential-for-pharmacokinetic
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.