The path of cannabis legalization in Canada has paved the way for its more common use both recreationally and medicinally. However, like any other substance, cannabis doesn't exist in a vacuum. Its interaction with other medications can lead to a variety of unexpected and sometimes dangerous consequences.
Interactions Elevating Cannabinoid Levels:
Medications such as ketoconazole, macrolides, and verapamil can potentially double the concentrations of THC and cannabidiol, the active cannabinoids in marijuana. This augmentation can lead to enhanced psychoactive effects and adverse reactions like the elevation of somnolence (a state of drowsiness) and transaminase (fatty liver disease).
Effects on Other Drug Levels:
Cannabidiol can significantly affect the levels of other drugs in the body. For instance, it can triple the active metabolite levels of clobazam. Moreover, combining marijuana with warfarin has been reported to cause very high international normalized ratio levels, leading to an increased risk of bleeding.
Specific Drug Interactions:
- Tacrolimus: When mixed with CBD, the serum concentrations of tacrolimus, a medication used post-transplant to prevent organ rejection, can increase threefold.
- Ketoconazole: This antifungal medication can double THC and CBD levels, intensifying marijuana's psychoactive effects.
- Rifampin: An antibiotic that can decrease THC concentrations by 20% and CBD levels by 60%, potentially affecting marijuana's efficacy in treating seizures.
Additive Effects:
Combining marijuana with sympathomimetics or central nervous system depressants like alcohol and opioids can lead to additive effects. These combinations could result in symptoms like tachycardia, hypertension, drowsiness, and confusion.
Potential Serious Interactions:
Drugs like warfarin, clobazam, and certain central nervous system depressants and sympathomimetics have been flagged for potentially serious interactions with marijuana. These could lead to increased risks of bleeding, benzodiazepine toxicity, and other additive effects respectively.
General Metabolic Interactions:
Marijuana can interfere with drug metabolism, posing additive effects or altering the levels or clearance of other drugs. It's vital for both patients and healthcare providers to be cognizant of these potential interactions and consider alternative medications when necessary.
Advice Moving Forward:
With the growing acceptance and use of cannabis, it's imperative for individuals, especially those on other medications, to consult with healthcare professionals before combining cannabis with other drugs. Given the recent uptick in the consumption of cannabis in some jurisdictions, clinicians could strive to provide alternative medications that do not interact with marijuana when possible, and patients should be advised about the possible increased cannabinoid effects with certain drug combinations.
The landscape of cannabis use and its intersection with other medications is still a developing field. Continued research, patient education, and open communication between patients and healthcare providers are crucial in navigating this complex terrain safely.
The interactions between cannabis and pharmaceuticals are multifaceted and can significantly impact an individual's health and well-being. As we continue to explore the benefits and risks associated with cannabis use, ensuring a thorough understanding of its interactions with other substances is indispensable for fostering a safer environment for all.
This post should be interpreted as commentary, not medical advice. If you have questions related to any adverse interactions cannabis may have when combined with prescription drugs, please speak to your doctor. As a general rule, avoid simultaneously using cannabis while also taking prescription drugs.
