As Cannabis Use Increases, Pharmacists Must Be Prepared to Counsel Patients


As more states have legalized cannabis use—both medicinal and recreational—Sera said pharmacists’ roles in counseling will become even more important.

In an interview with Pharmacy Times, Leah Sera, PharmD, MA, associate professor at the University of Maryland School of Pharmacy, discussed her presentation at the 2024 American Pharmacists Association (APhA) Annual Meeting and Exposition. As more states have legalized cannabis use—both medicinal and recreational—Sera said pharmacists’ roles in counseling will become even more important.

Q: Have you seen growth in the use of cannabis in recent years?

Leah Sera, PharmD, MA: Oh, definitely. It has increased and states that have legalized cannabis for recreational use have seen increase in cannabis use. And, you know, every state is different. From a federal standpoint, cannabis is still Schedule I, so it's still illegal. However, since the mid ‘90s, states had been making their own laws and the laws differ from state to state. Some states have recreational or, you know, you might hear them called “adult use” cannabis laws that allow adults typically over the age of 21 to purchase and use cannabis products. Some states have only medical cannabis legalized. Some states have sort of limited cannabis programs where only products that have very low amounts of THC or CBD are allowed. And there are still a couple of states, although not many, that have no cannabis program at all. But there have been a number of studies done showing that when recreational or adult use is legalized, then use does increase among those adults who are now legally able to purchase. But some good news is that it doesn't seem that those laws increase child or teen use, which is obviously something that is of great importance for us to monitor as cannabis becomes legal in more and more states.

Q: How is it possible that cannabis is federally Schedule I, and thus illegal, but legal in many states?

Leah Sera, PharmD, MA: Yeah, that's such a great question and such a complicated question. There's a lot of a lot of history there. But, you know, cannabis was placed on Schedule I when the Controlled Substances Act was passed, along with a number of other drugs. And Schedule I indicates that a drug has a high potential for abuse. But really, the critically important part of being Schedule I compared to Schedule II is that a drug has no accepted medical use. And that's why you can have drugs like, you know, like many of the opioids and even cocaine is a Schedule II drug because even though there is a high potential for abuse, as we know, those drugs have accepted medical uses.

There have been a number of arguments related to cannabis for why it shouldn't be Schedule I. First, the abuse liability is far lower than drugs that are Schedule II. But also, you know, the biggest point of contention is the accepted medical use. And there have actually been, I think, 4 citizen petitions since the ‘70s to try and get the DEA to remove cannabis from Schedule I. All of them have been unsuccessful, and because these had been unsuccessful, the states started taking matters into their own hands, starting with California in 1996, which legalized cannabis for medical use only at that time. And that was sort of the beginning and then other states started to legalize cannabis for medical use, and then for adult use, to the to the point where the majority of states and also some territories—Washington, DC—do have some sort of legalization of medical cannabis or cannabis-based products. And as a sort of continuation of this, because I also think it is so interesting and complex, this has been a very hot topic of conversation. And a caveat is that policy's not really my area of expertise, but I'm just so interested in it as it relates to cannabis.

Some things may be about to change. You never know for sure, but the FDA, or Department of Health and Human Services via the FDA, recently reviewed all of the evidence related to cannabis, because the president asked them to review cannabis scheduling. And so in August, HHS sent a letter and report to the DEA requesting that cannabis be moved from Schedule I to Schedule III, which is huge, because in the past HHS and DEA had been on the same page—cannabis should be Schedule I. And although there have been citizen petitions to change the schedule of cannabis or to remove cannabis from the CSA altogether, this is the first time that that another government entity has requested this. And to date, the DEA has never denied a request like this from HHS. And now what that would mean, you know, is also complicated, but the biggest impact I think that that would have…in my opinion, the biggest change is just in terms of how it could be perceived by our medical community. And so even though things may not change—you know, it would not, for instance, it wouldn't make all of the cannabis products that you can go into a dispensary and buy, that would not make them legal, you know, because products still have to be approved by the FDA—but it could really change how we as a medical community view cannabis as a potential therapeutic modality. So, it's very exciting time.

Q: What should pharmacists know about the various strains, formulations, etc. of cannabis?

Leah Sera, PharmD, MA: Yes, I think that one of the points that I would recommend that pharmacists know is that strains should be identified, or kind of classified, not by their names, which are often fun, but by their relative concentrations of cannabinoids, typically THC and CBD. And that's because knowing the brand names of those strains is just not very helpful. You know, Purple Haze in one state is not going to necessarily have the same cannabinoid profile as Purple Haze in another state. And so, there's no standardization or consistency between those. So, it's just best, when you're talking to patients about cannabis products, to talk about them in terms of their relative cannabinoid concentrations. It's much more meaningful. Another thing is that although inhalation as an administration technique is still the most popular, highly favored among users, the oral formulations and things like tinctures are much easier to dose and titrate. It's much more accurate and it avoids the potential pulmonary side effects that you would have, especially with smoking cannabis. So those are, I think, the top things that I would suggest to pharmacists.

Q: There are many discussed benefits of cannabis use, but which are real and how do you parse that out?

Leah Sera, PharmD, MA: You know, again, it’s actually probably good that we were talking about the kind of current regulatory landscape of cannabis and how things might change because in this long report that HHS sent to the DEA, they identified a few, what they would consider accepted medical uses for cannabis and cannabis-based products. And those are for the treatment of pain—a lot of the studies have been done related to neuropathic pain—nausea and vomiting, and anorexia that's related to a medical condition like HIV/AIDS. Those are the 3 that that they concluded that there was enough evidence to show that there was an accepted medical use for these conditions. And then also, we know that the FDA approved CBD oil in 2018 for the treatment of severe seizure conditions that primarily occur in children. For everything else, you know, it's a question mark still. Studies maybe either have conflicting results or they have positive results, or they're very small or they don't have rigorous methodology. That's another reason why I'm hopeful that removing cannabis from Schedule I will encourage and make possible more research into some of these areas. You know, I think a lot of people believe that either cannabis isn't good for anything, or cannabis is good for everything. We know that with drugs, it's somewhere in the middle. There are benefits, there are risks, not everybody should use it, but maybe for some people and for some conditions, it is going to be beneficial. And for that we need more research.

Q: What are some potential drug–drug interactions with cannabis that pharmacists should know about?

Leah Sera, PharmD, MA: The first one is more of a pharmacodynamic interaction. Cannabis can make people feel sleepy, and so it can act synergistically with any other drugs that also have that sort of sedating effect, so alcohol, opioids. That is a big one and maybe obvious, but I wanted to point it out anyway. As you said, there are lots of potential kind of hypothetical effects. Cannabis is metabolized and effects that cytochrome P450 system, so there's a lot of hypothetical drug–drug interactions. So, I think it's important that pharmacists are aware of that metabolic pathway for cannabinoids, at least for THC and CBD, and probably others as well, in terms of what we know from case reports and from the medical literature. There have been a number of case reports related to increased [international normalized ratio] and bleeding episodes in patients using either THC or CBD, and so that's probably again due to an interaction related to the cytochrome P450 system. But that's one that I think is really important for pharmacists to know about.

Q: What are potential drug­–disease interactions pharmacists should be aware of?

Leah Sera, PharmD, MA: There's been a lot of a number of new studies lately published about the cardiovascular risks associated with cannabis, particularly smoking cannabis. We do know that THC can increase heart rate, it can increase blood pressure, it can increase platelet activation. And smoking cannabis has many of the same negative effects as smoking cigarettes from a cardiovascular standpoint, so cannabis and THC in particular, and certainly smoking, should be avoided in patients who have a history of severe unstable cardiovascular disease. And THC, especially, again, should also be avoided in patients who have a history of substance use disorder or cannabis use disorder. And finally, whole plant formulations, as opposed to things like extracts, should be avoided in patients who are immunocompromised because the plants themselves may have things like fungal spores that can be very dangerous to a patient who is immunocompromised.

Q: How can pharmacists effectively counsel patients with questions about cannabis use?

Leah Sera, PharmD, MA: In my opinion, pharmacists should be able to provide information on contraindications, precautions, adverse effects, and drug interactions, just like they would for any other therapeutic agent. Pharmacists should feel comfortable performing a DUR for medical cannabis, just as they would for any other medication, including things like whether or not the therapy is appropriate, if there are contraindications, and the potential for abuse in a particular patient. And then most importantly, I think that pharmacists should examine their own level of knowledge about cannabis and their own beliefs about people who use or who are looking for information on cannabis. Reducing the stigma surrounding discussions related to cannabis makes it easier for people to ask us questions about it, and that's what we want as pharmacists. We want patients to feel comfortable coming to us, the most accessible members of the health care team, with their questions about cannabis.

Q: Are there any other actions pharmacists should take with regard to cannabis?

Leah Sera, PharmD, MA: Yeah, I mentioned that the states all create their own laws about regulating cannabis and that includes the role of pharmacists in dispensing cannabis. So, I think pharmacists should become familiar with the laws in the states where they practice. And I also encourage pharmacists to stay current with the medical evidence that exists now related to the benefits and risks of using cannabis. If the DEA does agree to reschedule cannabis from Schedule I to Schedule III, then we may be seeing a lot more questions about it from both patients and from other health care providers. So, it's a good time to kind of bone up on your cannabis knowledge.

Q: Is there anything you’d like to add?

Leah Sera, PharmD, MA: Yeah, if you're interested in learning more about this topic, please come to my education session which is Friday, March 22 [at APhA]. And you can also learn more about our graduate studies and medical cannabis program at the University of Maryland School of Pharmacy by going to

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