Recreational and medical cannabis is now regulated and legalized in Canada and in some US states. Nevertheless, we have to keep in mind that THC-predominant cannabis remains a psychoactive substance that impacts your body in many ways. These effects can amplify or counteract your body’s response to some medications.
Before we delve into specific drug interactions involving cannabis, let’s define drug interactions.
There are two types of drug interactions:
1)Attacker vs Victim: attacker drug increases or decreases the amount of victim drug.
Interactions for which one drug or substance (attacker) changes the amount of another drug circulating in your body (victim). When the amount of the victim drug is reduced, its effect on your body can also be reduced. However, when the amount of the victim drug is increased, its effect on your system is too.
This type of interaction can happen at different moments from when the drug gets ingested to when it gets eliminated. There are 4 stages to a drug’s journey in your body:
- When taken orally, a drug has to be absorbed in a specific place in your gastrointestinal (GI) tract (stomach, intestines, etc.) in order to reach your bloodstream. However, one drug can affect the absorption of another drug. This type of interaction can happen in many ways.
- For example, a drug can change the pH of the stomach (acidity level). This pH change can prevent another drug from dissolving and crossing the stomach tissue
- Here’s another example. Two oral drugs that are taken together can bind together in your GI tract and form an insoluble and unabsorbable complex. This mechanism is called chelation.
- When it’s in the bloodstream, a drug has to be transported to its activity site (where it will produce its effect -> ex. brain, heart, kidney, etc.)
- Some drugs can interfere with the distribution or transportation of other drugs.
- Once in your body, many drugs have to be metabolized into active forms in order to produce their effect. Others get metabolized into inactive forms that don’t produce any effect. This transformation mainly takes place in the liver and is produced by specific enzymes.
- Some drugs can upregulate or downregulate these enzymes and therefore alter another drug’s activation or inactivation.
- Most drugs get eliminated from your body through your kidneys.
- Through different mechanisms, one drug can increase or decrease the renal elimination of another drug.
2) Effect battle: one drug’s effect on your body modifies your response to another drug
- In this situation, there is no change in the amount of the drug circulating in your body. It’s rather a change in the effect the drug has on your body. Two drugs that create opposite effects can lessen each other’s effects.
- This type of drug interaction doesn’t involve the mechanisms of absorption, distribution, metabolism, or elimination.
- These interactions occur at the activity site of the drugs (where the drugs produce their effect – ex. brain, kidney, heart, etc.)
- Example of effect battle interaction provided in Youtube video above at 1:04
Now you have all the right information to understand the interactions between cannabis and other medications.
Watch the Youtube video above from 2:05 to learn the most common drug interactions involving cannabis.
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- Drug interactions involving cannabis: Information for Health Care Professionals: Cannabis (p.27-28 and p. 150-151)
- Mechanisms behind drug interactions (in general):https://link.springer.com/chapter/10.1007/978-1-61779-213-7_2