Bioavailability is a method for measuring the amount of substances that reach the blood stream and represents a portion of the medicine that ultimately reaches the blood. It represents a percentage of the total dose administered. The higher the percentage, the higher the amount of a drug that enters the bloodstream. For example, if you swallow a medicinal tablet, 60% of the medicine might end up in your feces without ever having entered your blood stream. This means that the bioavailability cannot be higher than 40%; 100% is achieved only when the medication is administered intravenously (directly injected into the bloodstream).
Different routes of administration
will lead to different bioavailability. This can be very different per product, but in general, this is the rule:
1. Vaporized products
have a higher bioavailability than smoked products
2. have a higher bioavailability than orally administered products.
Ingesting oral cannabis products during a (high-fat) meal generally results in a higher bioavailability than when taking them on an empty stomach. This is also the case for other medications. For example, take into consideration the drug Nilotinib. It is used to treat a type of blood cancer called chronic myeloid leukemia (CML). The drug is strongly advised to be taken without food. Intake with food can result in overdose related effects, as Nilotinib has cardiovascular side effects, such as high blood pressure or an irregular heartbeat.1
Healthcare professionals need to consider this important factor when determining a patient’s treatment.
- Geissler, J. (2018). Food effect on Nilotinib: Presentation of the NIFO Study at ASH.