Beyond the Ingredients
Delivery systems key to proper penetration of the skin
By Janet McCormick
Originally published in Skin Deep, May/June 2009. Copyright 2009. Associated Skin Care Professionals. All right reserved.
When considering different products, knowledgeable estheticians can evaluate efficacy by scrutinizing ingredients. But, alas, ingredients are not the whole story of a product's effectiveness. The ingredient first has to get to the targeted area of the skin, then be released to perform its magic. This path to success is performed by a delivery system, says Rolando Urcuyo, formulation chemist at Allure Cosmetics in Hayward, California, a product formulation company. "Delivery systems are essentially vessels used to transport the right chemical to the right area or location in or on the skin, at the right concentration, in the right period of time," he says. He calls these the four Rs for choosing the best delivery system. A product can have wonderful ingredients, but if the delivery system is not appropriate, it cannot perform optimally and the formulation will be a failure.
History of Delivery Systems
The history of delivery systems can be traced to warriors enhancing their appearance to look stronger, tribes wanting to differentiate themselves, Cleopatra's introduction of cosmetics, and the development of simple skin care potions to relieve dry skin. Concoctions for all of these purposes sat on the skin's surface by means of simple delivery systems.
Modern cosmetics emerged in the 1940s when oil-in-water and water-in-oil emulsions that penetrated skin were developed. Commercial interests began to formulate skin products with functional delivery systems. Skin care evolved from merely topical treatment of dry skin to penetration, more diverse treatments, and the sophisticated, results-oriented products we have now.
In the 1960s and early 1970s, product performance moved to a higher therapeutic level, meaning products actually changed the skin. With ingredients that could bring about true change, controlling the delivery of these ingredients into the skin became necessary. As these delivery systems developed, the line between cosmetics and drugs became blurred, entirely due to their efficiency and penetration potential.
The Stratum Corneum
Ingredient delivery has a major barrier to surmount--skin. The skin's principal function is to prevent penetration of anything into the body such as water or harmful substances. Skin is the barrier between our organs and the outer world and skin is very good at its job. For that reason, delivery systems must fool Mother Nature to deliver ingredients to targeted areas so they can do what they are meant to do, whether on the skin or within it.
The real barrier to skin's penetration is the outer layer of the epidermis, the dead stratum corneum (SC) layer. The epidermis consists of keratinocytes, arranged in layers, which begin at the stratum basale and move through the epidermis to become a layer of dead cells at the surface. This layer, the SC, forms an excellent barrier to elements in the environment. Because keratinocytes of the SC are cornified, they are also called corneocytes and are filled with protein. The SC comprises 15-20 layers of corneocytes that every delivery system must penetrate.
An active ingredient is a substance that can provide beneficial properties like softness to the skin. These are generally listed on the label as ingredients responsible for the primary purpose of the product, such as exfoliation or moisturizing. The delivery system either places active ingredients onto the SC protective barrier or escorts them, so to speak, past that barrier. The ingredients are then transported to the target area. There are two means of penetration: the transfollicular route through the sweat gland ducts and pores of the hair follicles and the transepidermal route or intercellular pathway through the intercellular lipids in the SC. The principal pathway for skin penetration is the transepidermal route.
Penetration Mechanics
Penetration depth is different for every ingredient and its purpose and delivery systems are designed according to their functional need. For example, sunscreens are designed to stay on the surface or remain within the SC. Antiacne ingredients are designed to penetrate follicles. Antiaging products are designed to penetrate the epidermis, and for some, to stimulate the dermal matrix. Antioxidants are delivered to all layers of the skin. But none of these wonderful ingredients will perform properly on their own. Those designed to move past the surface of the skin require penetration of the SC, to be deposited by the delivery system in the functional level of epidermis or dermis.
The importance of a delivery system is obvious when discussing peptides, short chains of amino acids that offer various skin care benefits and signal a body's cells to perform specific functions. They are flexible in their potential uses and have wide applications in performance. Since their first application to skin care, peptide use has exploded in skin care formulations. But why did it take so long for their application in skin care? There has been no effective delivery system for peptides into the skin until now. Skin care peptide chemistry is defining a new category in skin care and new performance peptides are regularly being introduced.
Key Properties
There are key properties in an excellent delivery system.
-Controlled release at a target location.
-Improved efficacy through good penetration and encapsulation.
-Improved penetration of active ingredients into the skin.
-Nontoxicity.
-Separation of incompatible ingredients through encapsulation, as with hydrophobic (not readily absorbing water) and hydrophilic (readily absorbing water) active ingredients. This provides multiple benefits to performance.
-Stabilization of active ingredients that helps prevent their oxidation and discoloration of the finished product and offers longer shelf life and decreased loss of actives over time.
There are a number of systems available.
Emulsions are droplet-sized semisolid liquids that can aid ingredients in penetrating the top layers of skin, they were the first delivery systems, are widely used, and continue to grow in sophistication.
Liposomes are microscopic spherical vesicles (microcapsules) that form when phospholipids are hydrated. The resulting vesicles can hold ordinarily immiscible (non-mixable) materials, allowing for their controlled release to a target area. This permits timed release and high absorption of the ingredient.
Nanotechnology involves nanometer-sized particles of ingredients, about 100,000 times smaller than the width of a human hair, which penetrate the skin's layers more deeply. This technology penetrates so well it has sparked controversy as to just how deeply the particles go. Investigations are underway, cosmetic scientists do not want active ingredients to penetrate all the way through skin into systemic circulation.
There are many delivery systems but there is no one-size-fits-all. One delivery system that works in a formulation will not work in the next, one that works well for a given ingredient won't work for another. "Skin care ingredients must be paired with delivery systems to reach the desired site of action without (their) being inactivated or too concentrated," Urcuyo says.
The Unseen Factor
The trend to delivering even more efficient and sophisticated delivery systems is ongoing and will expand as newer and more results-oriented ingredients demand better and more targeted delivery. These systems pave the way for other innovations, including high-tech ingredients that trigger desirable cellular action, such as slowing signs of aging. With the marriage of new antiaging ingredients and emerging and sophisticated delivery systems, skin care will continue to advance toward the fountain of youth.
As estheticians, it is important we recognize that ingredients, their pH, their percentage of active ingredients, and other efficacy properties we have been taught are valuable to know. But another factor in product success is the delivery system, that mysterious mechanical mode of effectiveness we cannot see on the label. This unseen factor in skin care product formulation can only be tested when product is applied to the skin. If the delivery system works, those wonderful ingredients are being effectively carried into the skin. And that is what it is all about.
Janet McCormick is an esthetician, manicurist, and former salon owner and spa director. She holds a master's degree in allied health management, as well as a Comite International D'Esthetique Et De Cosmetologie (CIDESCO) diploma. She has written more than 300 articles and is owner of Spa Techniques Consulting. She can be reached at 863-273-9134 or janmccormk@aol.com.
When considering different products, knowledgeable estheticians can evaluate efficacy by scrutinizing ingredients. But, alas, ingredients are not the whole story of a product's effectiveness. The ingredient first has to get to the targeted area of the skin, then be released to perform its magic. This path to success is performed by a delivery system, says Rolando Urcuyo, formulation chemist at Allure Cosmetics in Hayward, California, a product formulation company. "Delivery systems are essentially vessels used to transport the right chemical to the right area or location in or on the skin, at the right concentration, in the right period of time," he says. He calls these the four Rs for choosing the best delivery system. A product can have wonderful ingredients, but if the delivery system is not appropriate, it cannot perform optimally and the formulation will be a failure.
History of Delivery Systems
The history of delivery systems can be traced to warriors enhancing their appearance to look stronger, tribes wanting to differentiate themselves, Cleopatra's introduction of cosmetics, and the development of simple skin care potions to relieve dry skin. Concoctions for all of these purposes sat on the skin's surface by means of simple delivery systems.
Modern cosmetics emerged in the 1940s when oil-in-water and water-in-oil emulsions that penetrated skin were developed. Commercial interests began to formulate skin products with functional delivery systems. Skin care evolved from merely topical treatment of dry skin to penetration, more diverse treatments, and the sophisticated, results-oriented products we have now.
In the 1960s and early 1970s, product performance moved to a higher therapeutic level, meaning products actually changed the skin. With ingredients that could bring about true change, controlling the delivery of these ingredients into the skin became necessary. As these delivery systems developed, the line between cosmetics and drugs became blurred, entirely due to their efficiency and penetration potential.
The Stratum Corneum
Ingredient delivery has a major barrier to surmount--skin. The skin's principal function is to prevent penetration of anything into the body such as water or harmful substances. Skin is the barrier between our organs and the outer world and skin is very good at its job. For that reason, delivery systems must fool Mother Nature to deliver ingredients to targeted areas so they can do what they are meant to do, whether on the skin or within it.
The real barrier to skin's penetration is the outer layer of the epidermis, the dead stratum corneum (SC) layer. The epidermis consists of keratinocytes, arranged in layers, which begin at the stratum basale and move through the epidermis to become a layer of dead cells at the surface. This layer, the SC, forms an excellent barrier to elements in the environment. Because keratinocytes of the SC are cornified, they are also called corneocytes and are filled with protein. The SC comprises 15-20 layers of corneocytes that every delivery system must penetrate.
An active ingredient is a substance that can provide beneficial properties like softness to the skin. These are generally listed on the label as ingredients responsible for the primary purpose of the product, such as exfoliation or moisturizing. The delivery system either places active ingredients onto the SC protective barrier or escorts them, so to speak, past that barrier. The ingredients are then transported to the target area. There are two means of penetration: the transfollicular route through the sweat gland ducts and pores of the hair follicles and the transepidermal route or intercellular pathway through the intercellular lipids in the SC. The principal pathway for skin penetration is the transepidermal route.
Penetration Mechanics
Penetration depth is different for every ingredient and its purpose and delivery systems are designed according to their functional need. For example, sunscreens are designed to stay on the surface or remain within the SC. Antiacne ingredients are designed to penetrate follicles. Antiaging products are designed to penetrate the epidermis, and for some, to stimulate the dermal matrix. Antioxidants are delivered to all layers of the skin. But none of these wonderful ingredients will perform properly on their own. Those designed to move past the surface of the skin require penetration of the SC, to be deposited by the delivery system in the functional level of epidermis or dermis.
The importance of a delivery system is obvious when discussing peptides, short chains of amino acids that offer various skin care benefits and signal a body's cells to perform specific functions. They are flexible in their potential uses and have wide applications in performance. Since their first application to skin care, peptide use has exploded in skin care formulations. But why did it take so long for their application in skin care? There has been no effective delivery system for peptides into the skin until now. Skin care peptide chemistry is defining a new category in skin care and new performance peptides are regularly being introduced.
Key Properties
There are key properties in an excellent delivery system.
-Controlled release at a target location.
-Improved efficacy through good penetration and encapsulation.
-Improved penetration of active ingredients into the skin.
-Nontoxicity.
-Separation of incompatible ingredients through encapsulation, as with hydrophobic (not readily absorbing water) and hydrophilic (readily absorbing water) active ingredients. This provides multiple benefits to performance.
-Stabilization of active ingredients that helps prevent their oxidation and discoloration of the finished product and offers longer shelf life and decreased loss of actives over time.
There are a number of systems available.
Emulsions are droplet-sized semisolid liquids that can aid ingredients in penetrating the top layers of skin, they were the first delivery systems, are widely used, and continue to grow in sophistication.
Liposomes are microscopic spherical vesicles (microcapsules) that form when phospholipids are hydrated. The resulting vesicles can hold ordinarily immiscible (non-mixable) materials, allowing for their controlled release to a target area. This permits timed release and high absorption of the ingredient.
Nanotechnology involves nanometer-sized particles of ingredients, about 100,000 times smaller than the width of a human hair, which penetrate the skin's layers more deeply. This technology penetrates so well it has sparked controversy as to just how deeply the particles go. Investigations are underway, cosmetic scientists do not want active ingredients to penetrate all the way through skin into systemic circulation.
There are many delivery systems but there is no one-size-fits-all. One delivery system that works in a formulation will not work in the next, one that works well for a given ingredient won't work for another. "Skin care ingredients must be paired with delivery systems to reach the desired site of action without (their) being inactivated or too concentrated," Urcuyo says.
The Unseen Factor
The trend to delivering even more efficient and sophisticated delivery systems is ongoing and will expand as newer and more results-oriented ingredients demand better and more targeted delivery. These systems pave the way for other innovations, including high-tech ingredients that trigger desirable cellular action, such as slowing signs of aging. With the marriage of new antiaging ingredients and emerging and sophisticated delivery systems, skin care will continue to advance toward the fountain of youth.
As estheticians, it is important we recognize that ingredients, their pH, their percentage of active ingredients, and other efficacy properties we have been taught are valuable to know. But another factor in product success is the delivery system, that mysterious mechanical mode of effectiveness we cannot see on the label. This unseen factor in skin care product formulation can only be tested when product is applied to the skin. If the delivery system works, those wonderful ingredients are being effectively carried into the skin. And that is what it is all about.
Janet McCormick is an esthetician, manicurist, and former salon owner and spa director. She holds a master's degree in allied health management, as well as a Comite International D'Esthetique Et De Cosmetologie (CIDESCO) diploma. She has written more than 300 articles and is owner of Spa Techniques Consulting. She can be reached at 863-273-9134 or janmccormk@aol.com.
