CBD may alter the effects of other medications. The altered concentration, in turn, may cause the medication to not work or increase the risk of side effects. These drug interactions are often difficult to predict, but they can cause unpleasant and sometimes serious problems. The documented effects of CBD on liver function and the enzymes that metabolize several drugs are relevant when considering whether or not CBD should be consumed with certain medications.
With the increasing use of CBD and its wide availability to the general public, it is important to examine and report on potential interactions between CBD and other therapeutic agents, as well as with addictive substances such as alcohol and tobacco. Although CBD did not affect the anticonvulsant activity of lacosamide, pharmacokinetic interactions between these two drugs cannot be excluded, since CBD increased the brain concentration of lacosamide and vice versa. CBD is known to interact with enzymes that metabolize cytochrome P450 drugs, and this affects the co-administration of CBD with other drugs that are also inhibited or metabolized by these enzymes. Similarly, when CBD was administered together with ethanol to rats, CBD was able to attenuate the alcohol-induced brain damage to the hippocampal and entorhinal cortices.
CBD acts on the same metabolites as grapefruit, so many prescription drugs that carry warning labels on grapefruit may have similar risks when taken with CBD. Despite the growing popularity of CBD as a drug for countless medical conditions, the limited availability of applicable pharmacokinetic and pharmacodynamic information highlights the need to start prescribing CBD using a “start small and go slow” approach, carefully observing the patient as desired and adverse effects. In addition to the more traditional ways of consuming cannabis, such as smoking, there is a growing interest in CBD oil, which only contains CBD and not the psychoactive component of cannabis, delta-9-tetrahydrocannabinol (THC). The interaction of these drugs with CYP3A4 leads to a slower degradation of CBD and, consequently, can lead to higher levels of CBD that are pharmaceutically active for long periods of time.
The increase in the anticonvulsant activity of AEDs was partly related to pharmacokinetic interactions with CBD because CBD increased the serum and brain concentrations of these AEDs. However, CBD inhibits CYP3A4, meaning that taking CBD and sertraline at the same time could be dangerous. A pharmacokinetic interaction between CBD and clobazam was reported, with a decrease in clobazam serum levels observed after an increase in CBD40 doses. Although the effects of CBD on alcohol consumption are not well understood, CBD is known to act as a 5-HT1A receptor agonist and the results suggest that CBD may attenuate alcohol consumption and potentially protect against certain harmful effects of alcohol, such as liver and brain damage.67.