Is CBD (Cannabidiol) Absorbed Through The Skin?
The pharmacist discusses whether or not topical CBD (cannabidiol) preparations are absorbed through the skin.
I am a kidney transplant patient with a fused back and a lot of back pain. I know I can not take CBD (cannabidiol) by mouth but can I use the topical cream or lotion? Thanks for the help.
Cannabidiol (CBD) is one of the many components of marijuana.
While delta-9-tetrahydrocannabinol (THC) is likely more well-known, CBD makes up nearly 40% of marijuana extracts (although this will vary by strain) and is considered to be 'non-psychoactive' in that it does not produce a 'high' or euphoria.
CBD is available is a variety of dosage forms, both over the counter (OTC) and through licensed dispensaries. Below are some of the most commonly utilized dosage forms:
- Topical creams or gels
Topical CBD products are widely available, but we don't fully understand its pharmacokinetic profile in terms of absorption through the skin and distribution of the drug in our body once applied. Additionally, there could be significant variability between CBD products.
We have a much better idea of how much CBD is absorbed when ingested orally versus transdermally (i.e. through the skin), and oral CBD is less than 20% absorbed.
The vast majority of studies that investigate the properties of topical CBD have only been done in animals (mostly mice) and there have been very few human studies.
In the studies done in humans, most include only a few subjects so further investigation is clearly needed to answer questions like how much of CBD is actually absorbed when applied topically.
Overall, based on the data available, topical CBD is not well absorbed through the skin but should at least have positive local effects (including antibacterial and anti-inflammatory effects).
Nevertheless, there are several topical CBD products being researched and developed that are utilizing 'absorption enhancers', designed to increase skin permeability and overall absorption.
The absorption of topical CBD products is discussed in more detail in the following sections.
Why Don't We Have More Data On Topical CBD Absorption?
Topical CBD products have simply not been as well studied as other dosage forms have, which is why we don't know much about their absorption.
This is partly due to the fact there are no FDA-approved prescription products intended to be applied to the skin and they aren't widely utilized in medical cannabis clinics.
We have far more data on the following dosage forms of CBD:
- Oromucosal Drops/Spray (A brand name product, Sativex, is available in Canada and contains both THC and CBD)
- Solid oral (e.g. capsules)
- Liquid solutions (an FDA approved product, Epidiolex, contains CBD and is indicated for the treatment of rare forms of seizure disorder)
Inhaling CBD yields the highest absorption rates, followed by oromucosal delivery (i.e. under the tongue or inside the cheeks) and then by oral dosage forms, which have poor absorption due to extensive metabolism in the liver.
CBD applied directly to the skin is thought to have minimal systemic (i.e. into the bloodstream) absorption without the use of absorption enhancers.
Topical CBD Benefits
Even though CBD products that are intended to be applied topically won't absorb very well into the bloodstream, several studies have shown that they can have significant local effects (in both human and animal studies), including:
- Wound healing
While more studies are needed, most available evidence is for the pain-relieving and anti-inflammatory effects when it comes to the topical application of CBD.
Numerous studies show that it demonstrates 'anti-nociceptive' (i.e. pain-reducing) activity and can 'down-regulate' pain signaling in the brain and spinal cord.
Additionally, it decreases the activity of several inflammatory mediators, such as:
- Tumor necrosis factor (TNF)-alpha
- Interleukin (IL)-1
- Interferon (IFN)-gamma
Enhanced Topical CBD Absorption
As mentioned previously, CBD, without the aid of an appropriate absorption enhancer, is not well-absorbed through the skin into systemic circulation.
Nevertheless, there are countless products and 'absorption enhancers' being researched that could change that, further increasing the potential use and effectiveness of topical CBD.
Topical CBD Absorption Enhances
One study, published in the European Journal of Pain, made a 'hydroalcoholic' gel preparation by dissolving CBD in ethanol, which was then mixed with several other components, including a polymer known as Carbopol 980.
This hydroalcoholic gel preparation showed significant systemic absorption (as measured by blood plasma levels) in rats, and produced a clinically significant anti-arthritic effect.
Other studies have produced similar CBD gels that contain high concentrations of ethanol mixed with phospholipids (these preparations are known as ethosomes). These CBD-ethosome complexes increased skin permeability and overall systemic absorption.
There are even pharmaceutical companies researching effective transdermal delivery systems for CBD.
One such company, Zynerba Pharmaceuticals, is developing a topical CBD product intended to treat a variety of medical conditions, including epilepsy and osteoarthritis.
The gel is proprietary and still under development, so we don't know the exact components, but it is described the following way on the company website:
ZYN002 is the first and only pharmaceutically-produced CBD, a non-euphoric cannabinoid, formulated as a patent-protected permeation-enhanced gel for transdermal delivery through the skin and into the circulatory system.
There is a lot of promise moving forward with topical CBD products, whether or not they are intended only for local effects (i.e. to the site that the CBD is being applied) or systemic absorption.
If you have been advised not to take oral CBD products, you should certainly speak with your doctor before using topical CBD products.
Although most don't have significant systemic absorption, there haven't been any studies to determine whether or not they may interfere with any drugs that you may be taking.
They likely won't pose any significant problems, but as mentioned, it is important to discuss use with your doctor first so you can receive appropriate advice for your specific medical situation and be monitored accordingly.
Answer SummaryUnless your topical CBD product has been specifically formulated for transdermal absorption, it won't penetrate the skin well or produce measured levels in the blood. It will likely only have local effects. However, several CBD products are in development that contain 'absorption enhancers', which increase skin permeability and can produce significant systemic absorption.
- Elsevier ClinicalKey: Cannabidiol Monograph
- A preliminary controlled study to determine whether whole-plant cannabis extracts can improve intractable neurogenic symptoms. PubMed
- Human skin permeation of Delta8-tetrahydrocannabinol, cannabidiol and cannabinol. PubMed
- A Systematic Review on the Pharmacokinetics of Cannabidiol in Humans PubMed
- Transdermal cannabidiol reduces inflammation and pain-related behaviours in a rat model of arthritis. PubMed
- Cannabidiol bioavailability after nasal and transdermal application: effect of permeation enhancers. PubMed
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