Drug interactions and Marijuana

The Problem

Illinois is about to embark on the marijuana experiment along with many other states.  Although just a pilot program in Illinois, the fingerprint left on the public will certainly be evident.  In Illinois, the physician and the patient will each be required to subscribe to an Illinois state database that they have met requirements that include a very long list.  Some of the requirements include: 

  • pay stub
  • voter registration card
  • notarized proof of residency
  •  bank statement
  • deed/title, mortgage, rental agreement
  • proof of renters/homeowners insurance
  • letter from a physician registered in the state who completed his/her own checklist

So now that the patient has that list together, look at your medications and look at this chart below to make sure you're good to go!

Physicians and pharmacists are in school for years learning to interpret charts like the one above quickly and meaningfully.  The main predictions these clinicians must try to make is the significance of increased, decreased or blocked metabolism of one substance from another.  This does not account for genetic variabllity in these metabolizing enzymes or the clinical studies that validate the significance.  Altering or continuing therapy is based on this ability.   Both of the primary care physician and pharmacist are eliminated from the care process because the marijuana physician is not the patient's primary care provider and the worker at a marijuana dispensary is not a pharmacist.

The Argument

Patients deciding to use medical marijuana are at increased  risks of drug interactions from not having the proper monitoring or warnings from qualified medical professionals.  There is a significant risk of the drug interactions causing increased hospital visits and possible deaths in patients who are not properly monitored.  

This is so because many of the medications that marijuana interacts with include heart medications, antibiotics, blood thinners and blood pressure medications.  In addition, the starting dose for patients to begin marijuana is highly variable depending on medications the person is taking.  The biggest area of concern are those medications that will block marijuana metabolism causing overdoses of marijuana.  This can lead to confusion, decreased consciousness, vomiting, anxiety, and rapid heart rate to name a few--all very concerning for patients with a lot of health conditions. 

With there being 558 medications that interact with marijuana, this is going to be a guessing game for emergency response teams and hospital staff alike.  When regulators have spent time creating hurdles for patients and prescribers, they should have spent resources to assure public safety from drug interactions and misuse--like prescription medications.  

The Facts

  • Marijuana is known to interact with 558 different medications 
  • Marijuana, whether smoked or eaten will cause the same drug interactions
  • Most patients' primary care provider will not be prescribing marijuana
  • Dispensaries do not have the ability to educate or interpret drug interactions like a pharmacist in a licensed pharmacy could
  • Studies for safety with all 558 interactions with prescriptions drugs have not been done 

The Solution

Marijuana use is still in an experimental phase.  It should be used in extreme caution or even avoided for patients taking certain medications.  Your primary care physician and pharmacist are going to be your best resource for interactions between marijuana and your current medication list.  Not only do they have the best understanding but they also know your history the best.  Do not stop or alter your current medications in anticipation of interactions without consultation with your doctor or pharmacist.  Your pharmacist can interpret the data for you physician to help them make a decision to prevent or treat drug interactions you may have.  

About the Author

Kirk Heil is a pharmacist and former founder of Lagom pharmacy.

Kirk Heil is a pharmacist and former founder of Lagom pharmacy.