When getting to the marijuana dispensary the patient will be faced with different methods of ingestion and she/he should be familiar with terms such as bioavailability and onset of action. I will try to make it simple and please allow me some leniency when it comes to terminology. Bioavailability is the percentage of a drug or other substance that enters the circulation and causes its active effect. The onset of action will be the time elapsed between the ingestion or delivery of the cannabis and its onset of action.
There are different ways of delivery of medical marijuana:
1. Oral as in edibles and capsules. The bioavailability is 8% and the effects last for an average of 6 hours. First pass metabolism by the liver with production of 11 OH THC which is a strong psychoactive component.
2. Vaping, the fastest route to onset of action but the effect last for 2 hours. Avoid first pass hepatic metabolism. Bioavailability of 30%.
3. Sublingual, is the second fastest route after vape, however some reflex swallowing may be present in which case the bioavailability will decrease and it will be also metabolized by the liver as it is swallowed. In general, its bioavailability is slightly superior to the oral preparations.
4. Bucal of oromucosal: place the oil between gum and cheek and by doing so you avoid swallowing and bioavailability will be improved.
5. Rectal: the bioavailability is twice of oral ingestion, however a clear rectum is needed and the suppository should be THC hemisuccinate which is not always available.
6. Transdermal, works better for CBD than THC and avoids first pass metabolism, however there are no studies about this method of delivery and cannabinoids are hydrophobic so is not known how well will be absorbed. Nano-emulgel will be a way of increasing absorption for
transdermal preparations.
So, an easy way to remember vaporizing is 4 times more effective than oral ingestion but its duration of action is shorter: 2 hours vs 6 of the oral dose.
If you vape, divide the daily dose in 8 doses and vape every 2 hours. If you take oral preparations take them every 6 hours.
Hope it will help and keep us posted of your progress.
Walk in Beauty!
By Fernando Fandino-Sende, MD
