Cannabidiol (cbd) - Femara (Letrozole) Interaction
Herbal: Cannabidiol (cbd)
Drug: Letrozole
Brand names:
Femara
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Jul 22, 2023
Interaction Details
Letrozole is classified as belonging to the following category: Cytochrome P450 2C19 (Cyp2C19) Inhibitors
Theoretically, CYP2C19 inhibitors might increase cannabidiol levels.
Cannabidiol is a substrate of CYP2C19 enzymes. Theoretically, drugs that inhibit CYP2C19 enzymes might increase levels of cannabidiol, increasing its effects and adverse effects.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Epidiolex (cannabidiol) prescribing information. Greenwich Biosciences, Inc., Carlsbad, CA, 2019. Available at: https://www.epidiolex.com/sites/default/files/EPIDIOLEX_Full_Prescribing_Information.pdf (accessed 5/9/2019)
Interaction Details
Letrozole is classified as belonging to the following category: Cytochrome P450 3A4 (Cyp3A4) Substrates
Cannabidiol might increase levels of drugs that are metabolized by CYP3A4.
In vitro and animal research shows that cannabidiol inhibits CYP3A4. In human studies and case reports, cannabidiol has been associated with an increase in plasma levels of the CYP3A4 substrates zonisamide, tacrolimus, everolimus, citalopram, and methadone.
Interaction Rating
Likelihood of Occurrence
PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
References
- Yamaori S, Ebisawa J, Okushima Y, et al. Potent inhibition of human cytochrome P450 3A isoforms by cannabidiol: role of phenolic hydroxyl groups in the resorcinol moiety. Life Sci 2011;88(15-16):730-6.
- Harvey DJ. Absorption, distribution, and biotransformation of the cannabinoids. Marijuana and Medicine. 1999;91-103.
- Bornheim LM, Everhart ET, Li J, Correia MA. Characterization of cannabidiol-mediated cytochrome P450 inactivation. Biochem Pharmacol 1993;45(6):1323-31.
- Gaston TE, Bebin EM, Cutter GR, Liu Y, Szaflarski JP; UAB CBD Program. Interactions between cannabidiol and commonly used antiepileptic drugs. Epilepsia. 2017 Sep;58(9):1586-92.
- Leino AD, Emoto C, Fukuda T, Privitera M, Vinks AA, Alloway RR. Evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus. Am J Transplant. 2019;19(10):2944-2948.
- Wiemer-Kruel A, Stiller B, Bast T. Cannabidiol Interacts Significantly with Everolimus-Report of a Patient with Tuberous Sclerosis Complex. Neuropediatrics. 2019.
- Madden K, Tanco K, Bruera E. Clinically Significant Drug-Drug Interaction Between Methadone and Cannabidiol. Pediatrics. 2020;e20193256.
- Anderson LL, Doohan PT, Oldfield L, et al. Citalopram and Cannabidiol: In Vitro and In Vivo Evidence of Pharmacokinetic Interactions Relevant to the Treatment of Anxiety Disorders in Young People. J Clin Psychopharmacol. 2021.
- Nasrin S, Watson CJW, Perez-Paramo YX, Lazarus P. Cannabinoid Metabolites as Inhibitors of Major Hepatic CYP450 Enzymes, with Implications for Cannabis-Drug Interactions. Drug Metab Dispos 2021;49(12):1070-1080.
Letrozole Overview
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Letrozole is used treat early breast cancer in women who have experienced menopause (change of life; end of monthly menstrual periods) and who have had other treatments, such as radiation or surgery to remove the tumor. It is also used to treat early breast cancer in women who have experienced menopause and who have already been treated with a medication called tamoxifen (Nolvadex) for 5 years. Letrozole is also used in women who have experienced menopause as a first treatment of breast cancer that has spread within the breast or to other areas of the body or in women whose breast cancer has worsened while they were taking tamoxifen. Letrozole is in a class of medications called nonsteroidal aromatase inhibitors. It works by decreasing the amount of estrogen produced by the body. This can slow or stop the growth of some types of breast cancer cells that need estrogen to grow.
Cannabidiol (cbd) - More Interactions
Cannabidiol (cbd) interacts with 1004 drugs
Interaction Rating Key
These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.
Major | The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur. |
Moderate | Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur. |
Minor | Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction. |
Unknown | No interactions have been reported or no interaction data is currently available. |
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Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Drug descriptions are provided by MedlinePlus.