THE REAL CANNABIS TOPICAL
The skin is the great wall of our own biological kingdoms. It is the largest organ of the human body, protecting everything that is truly precious to us. Like a fortress, it is very difficult to penetrate these walls. After all, the outer layer of skin is nothing but elongated dead skin cells stacked in layers.
Penetrating the Barrier
As one study describes, "the greatest obstacle to transdermal drug delivery is the barrier property of the stratum corneum [the outer layer of skin], a 10 micrometer (µm) to 20 µm thick tissue layer composed of a structured lipid/protein matrix ." Because of this, transdermal methods of drug delivery can be very challenging to get right. Simply using coconut oil (or any other oil), which many topicals on the market today are made out of, won't cut it.
Studies show that particle size is incredibly important for transdermal transportation of topical molecules. Topicals with a particle size of 500 nanometers (nm) or more cannot penetrate the stratum corneum. Once the particle gets down to about 80 nm it is able to diffuse into the epidermis . To put this into perspective, classical emulsions prepared with coconut oil have a droplet size of 1-10 µm , that’s 1,000-10,000 nanometers! So 80 nm is an incredibly small particle size. How is it possible?
What Are Nanoemulsions?
Nanoemulsions are a relatively new form of cosmetic product and a very effective method of transdermal delivery. Some of its features are:
Easy to spread on skin with no greasy feeling
Small droplet size for increased skin penetration
A nanoemulsion is essentially a micro-carrier* which reduces the droplet size of the medium (down to 10-100 nm) to improve permeability through the skin . Due to its structure it is able to carry both hydrophilic and hydrophobic active substances through the skin. There are two methods of preparing a nanoemulsion: low- and high-energy emulsification. Low-energy emulsification methods rely on chemical energy stored in the surfactants. High-energy emulsification relies on mechanical energy produced by ultrasound. High-energy methods are widely used because it gives a better quality emulsion (uniform droplet size, low polydispersity index) .
One can discern the difference between a nanoemulsion and a classical emulsion with the naked eye by observing the translucency of the topical. Nanoemulsions, in their water phase †, will exhibit a transparent or translucent appearance if the droplet size is small enough while a classical emulsion will appear creamy white. In addition to this, nanoemulsions will have more of a fluid nature while classical emulsions will be more viscous. One study compares the penetration abilities of a nanoemulsion vs. a classical creamy emulsion. Looking at the image below, one can see that a nanoemulsion topical will make it to the epidermis and as far down as the stratum basale (the lowest layer of the epidermis). As we know, this greatly depends on the particle size of the topical .
* A micro-carrier is a medium used to improve permeability of therapeutic agents through the skin. Micro-carriers consist of ethosomes, nanoemulsions, liposomes, and polymeric nanoparticles .
† Water phase is referring to the pure state of the nanoemulsion. Our topicals are actually fairly thick and cream colored. This is due to adding thickeners and other ingredients after the water phase. This does not affect the penetrative abilities of the nanoemulsion.
Left: Distribution of a nanoemulsion-based formulation Right: a commercial cream topical prepared with a classical emulsion.
The Endocannabinoid System
So what happens once the topicals gets through that barrier? That's where the endocannabinoid system comes in. The body contains a system of receptors all throughout the body that certain chemicals (classified as ligands), produced by our body, connect to. Cannabinoid molecules, also a type of ligand, connect to these receptors. The endocannabinoid system is so important in regulating many of our bodily functions. One such function is the regulation of inflammatory responses.
There are two types of endocannabinoid receptors, CB1 and CB2 receptors, found throughout the body. “The body contains two main cannabinoid receptors: CB1, the psychoactive receptor that also mediates pain and many other functions, and CB2, a non-psychoactive receptor that mediates pain and inflammation,” says Ethan Russo, MD, a cannabinoid researcher and the former president of the International Cannabinoid Research Society (ICRS). According to a study in the Journal of Dermatological Science, CB1 and CB2 receptors are abundant in our skin’s epidermal cells and sensory nerves . When topicals are applied, cannabinoids bind to the receptors in the skin, muscle tissue and local nerves and pain relief quickly ensues. THC binds to both CB1 and CB2 receptors in the skin, says Dr. Russo.
Furthermore, because cannabinoids are naturally fat-soluble, they are unable to penetrate into the bloodstream via transdermal delivery. For THC to have a psychoactive effect, it needs to enter the bloodstream and pass the blood-brain barrier to reach the brain. This is why most topicals do not have a psychoactive effect. However, because nanoemulsion topicals are water soluble, there is a chance that this topical will have a psychotropic effect. For some, this is an added bonus. However, with our high CBD topicals there have not been any reported cases of this happening.
As demonstrated, there is some pretty promising research out there illuminating the potential of cannabis topicals to interact with cannabinoid receptors near the skin. However, it is scientifically proven that most topicals on the market today cannot penetrate the outermost layer of skin, the most impenetrable layer of our skin. This just goes to show that nanoemulsion is the preferred method of preparing a cannabis topical formulation.
Where To Find Nanoemulsion Cannabis Topicals
Checkout Discovery Garden topicals in stores throughout Washington. Visit the website at www.dgcannabis.com
Ming-Jun Tsai, Yaw-Syan Fu, Yu-Hsuan Lin, Yaw-Bin Huang, Pao-Chu Wu. The Effect of Nanoemulsion as a Carrier of Hydrophilic Compound for Transdermal Delivery.
Rui Su, Wufa Fan, Qin Yu, Xiaochun Dong, Jianping Qi, Quangang Zhu, Weili Zhao, Wei Wu, Zhongjian Chen, Ye Li, Yi Lu. Size-dependent Penetration of Nanoemulsions Into Epidermis and Hair Follicles: Implications for Transdermal Delivery and Immunization.
N. Garti & O. Arkad. Preparation of Cloudy Coconut Oil Emulsions Containing Dispersed TiO2 Using Atomizer.
Reza Aboofazeli. Nanometric-Scaled Emulsions (Nanoemulsions).
Malgorzata A. Miastkowska, Marcin Banach, Jolanta Pulit-Prociak, Elzbieta S. Sikora, Agata Glogowska, Michal Zielina. Statistical Analysis of Optimal Ultrasound Emulsification Parameters in Thistle-Oil Nanoemulsions.
Victoria Klang, Julia C. Schwarz, Claudia Valenta. Nanoemulsions in Dermal Drug Delivery.
Sonja Stander, Martin Schmelz, Dieter Metze, Thomas Luger, Roman Rukwied. Distribution of Cannabinoid Receptor 1 (CB1) and 2 (CB2) on Sensory Nerve Fibers and Adnexal Structures in Human Skin.