10 Ways Medicine Interacts with Marijuana

There is always a lot of buzz surrounding the potential benefits of medical marijuana. Most recently, emerging research suggests that it may be a safer yet helpfully potent substitute for opioids to treat pain. But just as research demonstrates the possible benefits of using marijuana for treatment, questions remain about how cannabis might interact with prescribed or over-the-counter medications a person may also be taking.

A big challenge is imposed with understanding how marijuana interacts with other products – either prescribed or over the counter – because there are tight restrictions on how the Drug Enforcement Administration schedules marijuana. So even while many people may use marijuana, tight federal regulations limit researchers' ability to study cannabis as approved medications are typically studied, including evaluating whether it can safely be taken with medications.

Despite all the medical benefits of cannabis, there are many drugs that it cannot replace. Blood pressure medication, blood thinners, anxiolytics, seizure medications, and chemotherapeutics are common medications that have not demonstrated adverse side effects in conjunction with medical marijuana.

Did you know most cannabis-drug interactions can be traced back to liver metabolism? The liver has necessary enzymes called Cytochrome P450 (CYP450) that metabolize most drugs that we take. Cannabinoids like THC and CBD are also metabolized by these enzymes. Other medications can alter the effectiveness of CYP450 enzymes; in the case of cannabis, this can cause your other medicines to get metabolized more slowly. As a result, your prescription medication will remain in your system longer and at higher levels than intended, which can sometimes cause unwanted side effects.

Cannabis also has possible interactions with medications unrelated to liver metabolism. For example, some case studies have shown that cannabis combined with SSRI antidepressant medications like Zoloft and Prozac can potentially induce hypomania (elevated moods, racing thoughts, decreased sleep, grandiose ideas, and talkativeness). It is also crucial to pay attention to the route of administration/ingestion.

The health of your liver is an example of a factor that can determine whether the current dose of cannabis you use is safe with your other medications. Always speak with your primary care doctor before trying medical cannabis.

Furthermore, everyone's cells have different concentrations of the CB1 and CB2 receptors that cannabinoids activate. Some people also have variations in their CYP450 enzymes, which make them less effective at metabolizing cannabinoids, making even low doses of cannabis have more potent effects on them.

If you notice that cannabis is affecting your medications and causing severe side effects, it is recommended that you cease cannabis use and notify your medication prescriber as soon as possible in case doses need to be adjusted; according to Mayo Clinic, Marijuana may affect people's blood-sugar levels; indeed, some studies have found that marijuana users are less resistant to the effects of insulin, the hormone that helps blood sugar get inside cells.

This could mean that their systems can better control their blood sugar levels. They also recommended that people who take marijuana with drugs for diabetes should be monitored closely, and adjustments to their medications may be necessary.

What research is out there, an example of medicine that could interact dangerously with marijuana is benzodiazepines. Like Valium, Xanax, or Klonopin, a class of drugs primarily used to treat anxiety, can be prescribed for other things as well, i.e., managing insomnia.

However, CBD in marijuana can inhibit an enzyme the liver uses to metabolize medicine like benzodiazepines so that levels of the medication in the body go up. It can increase the blood levels of those benzodiazepines and cause more sedation, potentially leading to problems like overdosing on the medication.

THC/CBD can slow down the metabolization of cholesterol medications like Lipitor, too. Researchers state that is important because some people have bad reactions to cholesterol medicines like pain in their muscles, potentially making those reactions worse.

Conversely, marijuana use may reduce the effectiveness of other medications, including antidepressants like Cymbalta or duloxetine.

For example, one study reported that just in clinical practice, patients that smoke a lot of marijuana and that are on something like Cymbalta need higher doses to get a good effect. That could be because marijuana is speeding up the metabolism of that antidepressant.

Here are a few more fun facts relating to medical cannabis and prescription drugs:

1.Warfarin

THC and CBD increase warfarin levels.

2.Alcohol

Alcohol may increase THC levels.

3.Theophylline

Smoked cannabis can decrease theophylline levels.

4.Indinavir or Nelfinavir

Smoked cannabis had no effect.

5.Docetaxel or Irinotecan

Cannabis-infused products (like tea) had no effect

6.Clobazam

In children treated with CBD for epilepsy, CBD increased clobazam levels

7.Tacrolimus

CBD increases tacrolimus serum concentrations threefold. It does not affect THC levels.

8.Ketoconazole

Can double THC and CBD levels.

9.Rifampin

Decreases THC concentration by twenty percent and CBD by sixty percent.

10.Fluoxetine

No interactions between THC. Further research is needed on CBD

Considering more permissivechanges in the political andcultural climate surroundingmarijuana use, physiciansshould keep an eye out forinteractions betweenmarijuana and prescriptiondrugs—especially in theelderly and those withchronic health conditions.Furthermore, they should askabout marijuana use as adetailed history and physicalexamination.