Navigating Cannabis in Pharmacy Practice: State Legislation and Contraindications for Patient Use

Although not federally legal, cannabis has been more broadly adopted and accepted for recreational and medical use in the United States due to numerous states legalizing the drug, bringing with this shift a need for pharmacists to become more educated about cannabis from a drug information perspective, explained Leah Sera, PharmD, MA, associate professor, University of Maryland School of Pharmacy, during a presentation at the American Pharmacists Association 2024 Annual Meeting & Exposition in Orlando, Florida. Additionally, Sera explained that pharmacists should learn about the legalities of cannabis use in the state where they practice, as legalization or lack thereof can differ from state to state significantly.¹

“Like opioids, cannabis has been around for thousands of years, and we’ve been using it as a medicine for a long time. Cannabis was introduced to the world of Western medicine in the 19th century by an Irish physician working in India, and it was actually included in the [US Pharmacopeia [USP] starting in 1851,” Sera said in the session. “At some point in our past, we thought cannabis was medicine. However, in the early decades of the 20th century, concern about recreational cannabis obscured the medical and industrial uses of cannabis and it was essentially prohibited in 1937 and removed from the USP in 1942.”¹

In 1996, California became the first state to legalize medical cannabis. Following California’s legalization, there was a snowball effect across the country that led to other states decriminalizing or legalizing cannabis use in some way.¹ As of November 2023, 38 states, 3 territories, and the District of Columbia (DC) allow the medical use of cannabis, and 24 states, 2 territories, and DC have either decriminalized or legalized cannabis for recreational use.²

“However, it remains, at least today, classified federally as a schedule 1 drug,” Sera said. “But there was some real movement in August of 2023, when the Department of Health and Human Services sent a recommendation to the DEA to move cannabis from schedule 1 to schedule 3.”¹

Because of the growing acceptance and adoption of cannabis as medicine, patients may ask pharmacists questions about cannabis use for either medical or recreational purposes. Sera noted that of key concern for pharmacists is whether cannabis use is safe for that patient, as there are contraindications for its use for certain patients.¹

“In terms of cardiovascular disease, there have been some observational studies that show that cannabis may be a risk factor for the development of heart failure and a risk factor for stroke,” Sera said. “There is [also] some evidence of a statistical association between cannabis and triggering a myocardial infarction.”¹

However, Sera noted that a lot of the studies that have shown cannabis may be a risk for cardiovascular disease have been conducted with patients who use cannabis recreationally and smoke the drug, so these data may not be applicable to patients who solely use cannabis for medical purposes. Sera explained further that people who use cannabis for recreational vs medical use likely use the drug a bit differently.¹

Sera explained further that people who use cannabis for recreational vs medical use likely use the drug a bit differently. Image Credit: © roxxyphotos - stock.adobe.com

“We don't know if the risk is the same [for recreational and medical use], but there is the potential for cardiovascular toxicity,” Sera said. “Patients who have unstable cardiovascular disease should be advised to avoid THC products or, if they're not willing to stop completely, to use the lowest possible dose of THC. Patients with severe respiratory disease should not use inhaled cannabis formulations. There is definitely evidence that links smoking cannabis to worsening respiratory systems, and that shouldn't be too much of a surprise.”¹

However, Sera noted there is no evidence that links cannabis smoking to chronic obstructive pulmonary disease, although the majority of the studies that evaluated this potential link were confounded by tobacco use. Notably, use of THC can worsen pre-existing psychosis or bipolar disorder, and it may precipitate the onset of psychosis in patients who are genetically at risk.¹

“This risk seems to be higher the younger an individual starts using cannabis. But again, a lot of these data come from recreational use, so it can be hard to sort of parse out what is the risk for someone who's using cannabis medically vs recreationally,” Sera said during the session. “We just really need more data.”¹

Patients who are pregnant or breastfeeding should not use cannabis, Sera noted. There is preclinical evidence that suggests exposure to cannabinoids is associated with short and long-term harms to developing offspring.¹

“Observational data are always complex,” Sera said during the session. “There's a lot of potential confounders, especially when we're looking at long-term harms that may influence these associations. But the recommendation, again, is to abstain from cannabis use for women who are pregnant or breastfeeding as cannabinoids do pass into the breastmilk.”¹

For relative contraindications, there are definitely risks for younger patients, especially those who are maybe genetically susceptible to developing conditions such as schizophrenia, according to Sera. But there are also younger patients who do use cannabis medically. However, Sera noted that patients who have cannabis use disorder or substance use disorder should be advised not to use THC products or to use very low doses of THC if they are not willing to stop completely.¹

Furthermore, patients who are immunocompromised may have a higher risk of infection when exposed to contaminated cannabis, explained Sera. Since cannabis is a plant that can be grown outside, it may be contaminated with fungal spores or other microorganisms. Additionally, patients who are immunosuppressed often take medications that can put them at a higher risk for interaction with cannabinoids. Older patients also may have physiological changes that can increase the risk or the magnitude of adverse effects (AEs) from cannabis. Such older patients may also be taking medications that can interact with cannabis, requiring assessment, according to Sera. Since cannabinoids are metabolized in the liver, patients who have severe liver disease may also be at increased risk of AEs when using cannabis.¹

For patients in whom cannabis is safe, there are very little data to guide a selection of a specific strain, explained Sera.¹

“There are lots and lots of choices, mostly with kind of strange and wacky names that mean very little in regard to the components of the cannabis products,” Sera said. “Actually, there was a study done, I think in Canada, where they compared the genetics of different names of cannabis and found that often strains were more genetically similar if they had a different name than if they compared strains with the same name. So don't go by the strain name.”¹

Instead, Sera noted it is beneficial to focus on the relative concentrations of cannabinoids, such as THC vs CBD, as well as terpenoids. Together, cannabinoids and terpenoids are used to classify the cannabis chemovar or chemotype, which is a more accurate identifier of cannabis than a strain name, according to Sera.¹

Of note, Sera explained that many clinicians view the convention of naming strains as a barrier to broader acceptance of cannabis as medicine within the medical community.¹

“Many providers would be hesitant to discuss something called granddaddy purple or guerilla biscuit or something like that [as medicine]. Other clinicians may just laugh it off or shrug it off—it really depends on the patient and the provider,” Sera said. “My opinion is that if we as health care providers can get used to talking with people about their bowel movements and about their sex lives, then we can probably handle this too.”¹

Sera noted that it is also valuable for pharmacists to be aware of the current evidence base for the therapeutic benefit of cannabis. Currently, there is conclusive evidence that cannabis is beneficial in the treatment of chemotherapy-induced nausea and vomiting, as well as severe epilepsy. There is also substantial evidence available for the use of cannabis to treat chronic pain, multiple sclerosis, and spasticity.¹

However, there is moderate evidence that cannabis is therapeutically beneficial in the treatment of insomnia, and limited evidence for the treatment of anorexia/cachexia (HIV/AIDS), Tourette syndrome, anxiety, and post-traumatic stress disorder. Additionally, there is insufficient evidence that cannabis is therapeutically beneficial for all other conditions. Yet, the most common conditions people seek out cannabis for are depression, chronic pain, insomnia, and anxiety, only 2 of which have any evidence base that supports its use for those conditions.¹

Additionally, Sera noted it is valuable for pharmacists as medication experts to assess their own biases around cannabis in order to approach discussions of cannabis with patients in an unbiased, nonjudgmental manner.¹

“I think it's important that when we talk about cannabis, we do so with empathy. We don't want to stigmatize patients,” Sera said during the session. “As the most trusted and accessible members of the health care team in the community, I also think pharmacists should become familiar with laws in their own state. Because as I said, these differ in every state, including with the pharmacist’s role in actually dispensing medications.”¹

REFERENCES

1. Sera L. You’ve Got a Friend in Cannabis. American Pharmacists Association 2024 Annual Meeting & Exposition; March 22-25, 2024; Orlando, Florida.

2. National Conference of State Legislatures. State Medical Cannabis Laws. November 8, 2023. Accessed March 22, 2024. https://www.ncsl.org/health/state-medical-cannabis-laws