A drug drug-interaction is based upon a change in the drug effect by providing a second one to the patient. This procedure is supposed to achieve a positive therapeutic result, but an adverse drug reaction may also occur.
Drug interactions happen on pharmacodynamic as well as pharmacokinetic levels. Cannabis-based medicines and cannabis per se can interact with other drugs. Cannabis-derived cannabinoids of utmost therapeutic interest are Tetrahydrocannabinol (THC) and Cannabidiol (CBD), as they do not only have a different potential for drug effects and but may also cause different pharmacodynamic interactions. Depending on the composition of the cannabis-based medicines, cannabis varies the risk for pharmakokinetic drug-drug interactions respectively. As well as the pharmacokinetics of Cannabis, THC and CBD can be influenced by other drugs (“victim”); they can perpetrate the levels of many drugs (“perpetrator”). The prescriber should be bear this in mind.