Cannabinoid Medicine Routes of Administration

By: Sarah Schwefel, Research Analyst and Content Writer, GCRC

There are multiple routes of administration when it comes to cannabis and hemp. We can take it orally, topically, oramucosally, and also by route of inhalation. As a consumer it is important we understand the pharmacokinetic properties of our plant medicine. In particular, knowledge of cannabis and metabolism is clinically important to understand the onset and duration of each method.

The absorbance of cannabinoids can be influenced by many factors such as drug lipophilicity, tissue differences, and bioavailability, which itself can be influenced by the individual route of administration.  Some opt for yet another route of administration via the suppository – this has one of the highest rates of absorption out of all but is the least used.

Oral administration by the way of edibles or tinctures most commonly, are extremely popular among consumers. Both THC and CBD are highly lipophilic and have poor bioavailability, estimated to be around 6%. This is because orally ingested cannabis or hemp have an extensive first pass metabolism. This a phenomenon of drug metabolism where the concentration of a drug, specifically orally administered drugs, is greatly reduced before it reaches the systemic circulation.

Because of this, it then results in lower peak plasma concentrations. Orally ingested cannabis has the longest onset of effect being anywhere from 60-180 minutes, however is favored among many patients due to its lasting effects of 6 to 8 hours depending on the individual. Though edibles can lead to undesired effects due to its delayed onset and high THC content in many on the market today.

On the other hand vaping and smoking cannabis both avoid the first pass metabolism. Smoked and vaped cannabis has similar pharmacokinetics, and both have a rapid onset of 5-10 minutes, which achieves rapid delivery of the cannabinoids from the lungs to brain. Peak plasma concentrations of both CBD and THC occur within 3-10 minutes after inhalation. The bioavailability of smoked THC and CBD varies, with reported rates between 8%-35%, with the effects lasting 2-4 hours on average.

Transdermal application also bypasses the first pass metabolism, as inhalation does, however absorption through this route is hindered by the intrinsic hydrophobicity of cannabinoid components. The can lead to poor drug diffusion across the aqueous skin layer. The onset of action and duration are variable and dependent on the quality of formulation.

Sativex is an oral mucosal spray containing a fixed ratio of equal CBD and THC that has been extracted by the cannabis sativa plant. It is approved by the EMA to treat moderate to severe spasticity in Multiple Sclerosis patients who have not responded adequately to other antispascity medications. Oramucosal forms of cannabinoids are rapidly absorbed through the oral mucosal and reduces the first pass metabolism, which in turn results in higher plasma drug concentrations.

When choosing our plant medicine it is important to consider these factors. Personally I smoke, vape, use edibles, tinctures, and topicals to get as many methods of absorption into my endocannabinoid system through out the day. As a chronic pain patient this allows my endocannabinoid system to absorb in multiple ways, while having various lasting effects.

My orally ingested plant medicine is great for pain management through out the day, while smoking and topicals I consider my breakthrough pain solution. When using cannabis and hemp for medicine it is important to always document your products. Write down the product details, time of onset, effects felt, and also any undesired effects felt. This allows us, as patients, to find what works best for us, and to rule out the options that do not.

It's a pleasure to have our Research Analyst Sarah write a GCRC content – it's both an editorial and an educational article that many will learn from.

 –Mike Robinson, Founder – Global Cannabinoid Research Center  / GCRC Publications Read The (HUG) Hemp Users Guide Contact Mike today about opportunities with GCRC