Another study investigating even higher doses of CBD also observed no cognitive or psychomotor impairments . This is particularly relevant for medical cannabis users, who commonly use CBD in the daytime to control symptoms. In line with a safety-focused approach, we recommend initiating cannabis when the patient is not performing safety sensitive activities until the absence of impairment has been established, as is done with many other pharmacotherapies. Generally, it is believed cannabis can be safely used with the majority of medications . A common concern is the concomitant use with CNS depressants leading to potential pharmacodynamic interactions. While importantly there are few formal drug-drug interactions, additive pharmacodynamic effects could lead to sedative or cognitively impairing adverse events. Clinicians should screen for recreational, prescription, and over-the-counter medications. Common depressants such as alcohol, opioids, antipsychotics, benzodiazepines, tricyclic antidepressants,vertical grow rack or antiepileptics may worsen sedation & cognitive impairment when coingested with cannabis .
Cannabis is metabolized in the liver by CYP 450 isoenzymes. THC is predominantly oxidized by CYP2C9, CYP2C19, and CYP3A4. CBD is predominantly metabolized by CYP2C19 and CYP3A4. As such, CYP inhibitors or inducers may alter serum levels of these cannabinoids via pharmacokinetic drug interactions. Notably, CBD is a potent CYP 3A4 inhibitor and risks interacting with some medications in the following table Currently known cannabinoid drug interactions are summarized in Table 2. It should be noted that although cannabis could theoretically impact drugs metabolized by the CYP enzyme family, in many cases, the relevance of cell or animal experimental findings has not yet been established in humans . Clinical trials involving Nabiximols have the most robust data surrounding clinical drug interactions and found most to be not clinically significant. Instead, pharmacodynamic interactions are more common with compounded sedation being seen with a number of drugs. However, more safety and drug interaction studies are needed. If a patient is at high risk, using high doses of cannabinoids, or is using a medication with a known or potential drug interaction careful monitoring should be implemented .
Each route of administration has different pharmacokinetic properties, and thus different onset and duration of action.The two most common medical cannabis routes of administration are inhalation and oral . Oral oil is preferred in most patients as it eliminates respiratory risk and allows for accurate dosing. Inhalation can be used, however, there is an increased risk for respiratory harm, especially in those with pre-existing respiratory conditions. If inhalation is deemed necessary, dried cannabis vaporization is recommended. Concentrates should be avoided due to the potential for contaminants, difficulties in accurate dosing, and the potential for health harms such as EVALI. Other dosage forms are available but there is insufficient safety evidence to make recommendations at this time. Regulatory protocols within a region and the source patients are obtaining their cannabis from dictates the risk of exposure to product contaminants. For example, in the legal Canadian market, cannabis grow racks producers must pass strict federal government mandated regulations with standardized testing for contaminants. In unregulated markets, there is a much greater risk that products may contain harmful matter.
Extraction processes to form concentrated cannabis products can involve solvents, which may leave toxic residues for consumption.High-quality cannabis products, free of contaminants and toxins, and from a regulated source, which has been tested according to regulatory requirements, are preferred for all patients . Clinicians in collaboration with their patients should consider product safety risks of concentrated products if they are being used in treatment . THC is the primary psychoactive component of cannabis. The majority of adverse events related to cannabis are THC-dose dependent. By contrast, CBD has a greatly reduced adverse event profile of cannabis use. Patient circumstance should be carefully considered when choosing an appropriate strain, as each strain could lead to a difference in response . In particular, there is a safety risk of high THC products in specific groups such as the elderly, under 25, history of mental health, heart conditions, other conditions where there may be sensitivities with THC with symptoms that may compound the effects of THC, and those in safety sensitive occupations .