AND PERSONAL CARE

Author

Dr. Nripen S. Sharma PhD, Salvona LLC

Bryan Grossman, and Sam Shefer PhD

ABSTRACT

The cosmetic and personal care global markets continue to offer opportunity for the invention and discovery of unique functional ingredients. When formulated into consumer products, the final brand must offer enhanced functionality for reasonable cost. Newly discovered or invented functional ingredients are often expensive, and sensitive to degradation as a result of bodily contact and the environment. Thus, there is a strong need to enhance functional ingredient performance through ingredient protection and protection of efficacy.

Smart encapsulation of such functional ingredients is one way to achieve these goals. The development of optimal delivery systems can produce delivery of the ingredient where it needs to be; when it needs to be there; and released from the protective design at a rate that both minimizes irritation and conserves ingredient concentration. By this means, the protected ingredient can be thoughtfully targeted and delivered at the optimal efficacy. Such delivery systems are “Smart Solutions” and they provide these benefits at an affordable cost. This chapter discusses in detail the need for “encapsulation” of functional ingredients. This discussion is followed by a description of current commercial delivery systems, principles of action, and issues solved. The chapter ends with a focus on unsolved issues and an intriguing number of questions that need answering in order for the delivery-system field to continue to expand in a cogent manner.

While the number and types of delivery systems have proliferated over the last decade, we have chosen to focus on three main types of delivery systems that continue to show promise as measured by their use in commercial cosmetic, personal care, and pharmaceutical products.

These include:

1. 1. Powder technologies, representing encapsulation of actives within microspheres. Examples chosen for this discussion include delivery systems with trade names that include, but not are limited to: Polypore™, Polytrap™, Macrobead™, Tagravit™ microspheres, microencapsulated fragrances, and MultiSalTM
   
2. 2. Lipid-based encapsulation systems, consisting of liposomes, solid lipid nanoparticles (SLN), SalSphereTM
   
3. 3. Sugar-based cyclodextrin technology

We discuss the need for advanced delivery systems for cosmetic and personal care active ingredients and their utility in novel formulations with enhanced performance. We also present specific cases of performance for dermatological applications and provide a comparison of the different technologies.

The chapter concludes with the technological challenges of delivery systems in the major areas of cosmetics and personal care: oral care, hair care, skin care, and perfumery applications. These challenges pave the way for future development of novel products.

Keywords: particulate delivery systems, topical application, microspheres, sub-micron spheres, liposomes, cyclodextrins, solid lipid nanoparticles, microencapsulation, functional ingredient compatibility, and skin-friendly formulations.

TABLE OF CONTENTS

8.1.1  Background and Motivation

8.1.2  Classification of Delivery Systems

a.  Powder Technologies

b.  Improving Performance – MultiSal

c.  Gel- based encapsulation systems

d.  Porous polymeric systems

8.1.3  Lipid-B based Encapsulation Systems

a.  Liposomes

b.  Solid Lipid Nanoparticles

c.  Lipid-based sub-micron technology – SalSphere

8.1.4  Sugar-Bbased Technologies

a.  Cyclodextrins

8.1.5  Other Delivery Systems

a.  HydroSal™ Technology

b.  Cellesence

c.  Fermenich

d.  Thermarome

e.  Givaudan

f.  Evoglass

1.  Retinol

2.  Menthol

3.  Resveratrol

4.  Benzoyl Peroxide

5.  Salicylic Acid

6.  Fragrances

8.1.6  Technical Challenges in Delivery Systems

References

8.1.1 BACKGROUND AND MOTIVATION

The world personal care industry is a multi-billion-dollar industry, with American global sales at about $38 billion dollars annually as per estimates in 2011 (Global Cosmetic Industry Magazine, June 2012). While the utility of single functional ingredients is well known, there has recently been an eager interest in both the cosmeceutical and nutraceutical combination of multiple ingredients for incorporation into finished products to achieve varied benefits. This trend also includes providing an aesthetic feel for formulations. Complementing dermatological with cosmetic technologies, skin care scientists and cosmetic formulators are challenged to design prototypes with the right concentration of actives and stability features. These challenges also include: programmed-release kinetics of different actives, penetration profiles, and clinical efficacy. For this reason, there are a number of delivery systems available that can provide solutions for the major issues associated with formulation and consumer efficacy of products.

A successful cosmetic delivery system is based on the identification of a ­suitable methodology to formulate with active ingredients and provide enhanced stability, consumer appeal, efficacy, market impact, and performance. While numerous delivery systems have emerged over the past decade,1 the most commonly known delivery system is that of oil-in-water emulsions. More recently, complex emulsion delivery systems have evolved. These include: microemulsions, Pickering emulsions,2 multiple emulsions, lamellar gels, and water-oil-water emulsions.

In order to include features such as enhanced skin penetration and performance, complex delivery systems have evolved. These include, for example, vesicular liposomes and niosomes (non-ionic surfactant vesicles that are comprised of polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, or saccharose diester), molecular (cyclodextrins), and particulate (microcapsules and matrix particles). More recently, nanosomes (defined as modifications of liposomes comprised of very small, single bi-layer vesicles manufactured by application of ultrasonic energy to large, multilayer liposomes) and sub-micron sphere technologies such as SalSphereTM have been developed.

Cosmeceuticals have become widely used in the cosmetic, personal care, and pharmaceutical industries. Typically, ingredients employed include alpha hydroxy acids, glucans, enzymes, and antioxidants. For these systems, it is important not only how the active is delivered to the deeper skin layers, but also, the effect of the active on the release of other ingredients in the formulation.

Difficult-to-deliver actives, such as enzymes, can be successfully delivered to skin by prevention of foreseeable and immediate skin-protein-enzyme interactions and thus, loss of enzyme activity. Sustained release of such enzymes and their interaction with the skin proteins is essential for effective delivery, and the method to achieve this is via encapsulation of the enzyme in liposomes3 or nanoporous silica spheres.4 Also, dextran-conjugated enzymes can be produced. Enzymes can degrade due to surfactants as well as a result of contact with other ingredients in the formulation.

The benefits of suitable encapsulation of functional ingredients/API’s (i.e., Active Pharmaceutical Ingredients) for dermatological applications are:

Enhanced stability. The system can be utilized to isolate poorly soluble, air-oxidative active ingredients that may interact with the other ingredients. This provides long-term product shelf life. The system can protect functional ingredients for reducing oxidation/thermal degradation without compromising efficacy. ­Examples of such difficult actives include salicylic acid, resveratrol, minoxidil, menthol, methyl salicylate, fragrances, and incorporation of acids into alkaline bases.

Reduced irritation. The encapsulation system can deliver small doses of the functional ingredient to reduce irritation and other side effects on the skin. Tools and techniques to monitor irritation include skin pH and RIPT (Repeated Insult Patch Testing). Nonorganic and alcohol-free suspensions will reduce irritation and skin dryness.

Ease of formulation. The encapsulation technology can improve formulation stability by providing stable, high-dose samples in water-based suspensions that can be readily diluted in aqueous-based formulation products.

Controlled release. The technology results in a long-lasting, sustained release of functional ingredients.

Enhanced bioavailability and efficacy. The hydrophobic/lipophilic nature of certain encapsulation agents can enhance the bioavailability of various functional ingredients. Making use of the balance of oil-loving and water-loving portions of these agents can enhance/enable penetration of actives to the intended site. This approach includes, for example: hydrophilic actives (and hence difficult to permeate through the outer hydrophobic surface of the skin), as well as actives that require a deeper penetration into percutaneous fat areas (under the dermis) by solubilizing the actives in skin-penetrating solvents (with some hydrophobic character), or by means of controlling the particle size.

Tools and techniques to assess performance and compliance typically include visual stability for assessment of uniformity of a product’s physical appearance, and encapsulation efficiency by the centrifugation process. Physical characteristics are usually assessed by using microscopy, particle size analysis, rheometers, and pH meters. The level of functional ingredient can be assessed using HPLC (High Pressure Liquid Chromatography) or GC (Gas Chromatography); clinical efficacy evaluation is determined by using in vivo tests.

8.1.2 CLASSIFICATION OF DELIVERY SYSTEMS

Classification of such delivery systems is classically based on the following ­categories: powder technologies, lipid-based encapsulation systems, and sugar-based encapsulation systems.

a. Powder Technologies:

Starch-based encapsulation systems

MultiSal™ MicroSphereTM Technology

MultiSal™ is a multi-compartment encapsulation that allows the release of multiple functional ingredients at the same location. This technology incorporates the sub-micron hydrophobic spheres discussed in the previous section into a larger, water-sensitive microsphere that averages 20–30 microns in diameter.5 The outer microsphere can be constructed out of various ingredients. These include: modified starches, gums, and other natural or synthetic polymers, all of which lend an additional layer of stability to ingredients encapsulated in the sub-micron spheres that reside within (Figure 1).

Figure 1: Structure and release procedure of MultiSal™ technology

The additional outer layer also provides another “compartment” in which to incorporate ingredients that can be isolated from those ingredients contained within the sub-micron spheres. This outer layer can also have a complementary effect such as an acid that will be first in the sequence of release so as to exfoliate the skin prior to other beneficial functional ingredients being released from the sub-micron spheres. MultiSal™ can be used in most anhydrous product applications and can, depending on the type of encapsulation, be used in oil-in-water emulsion systems.

One of the main benefits of the additional encapsulation layer of MultiSal™ technology is that of stability. This system can withstand temperatures of up to 160°C before breaking down. Ingredients that would be susceptible to loss during heat processing are now protected, retained, and only released on skin when triggered by moisture in the presence of rubbing. Figure 2 below shows the retention of menthol under heat stress when encapsulated in MultiSal™ vs. menthol in free form. The technology is able to protect and retain a significantly higher ­percentage of menthol, which translates to a higher aroma intensity and efficacy in a final product.

Figure 2: Enhanced stability of menthol using MultiSal™ technology

b. Improving Performance

MultiSal™ offers the benefits of two types of release: water-triggered, and ­sequential delivery of multiple ingredients. The outer shell of MultiSal™ is sensitive to moisture and will break down in the presence of the application of shearing action achieved by rubbing on the skin. Therefore, an ingredient such as menthol, discussed above, can be retained until triggered, thereby creating an “on demand” release kinetic. Because this technology is a multi-component system, there are two compartments in which ingredients can be stored. The ingredients in the outer shell will be released first, with the encased sub-micron spheres being deposited at the same time. Ingredients that are encapsulated in the sub-micron spheres will then release over an extended period and to deeper layers of skin since the submicron spheres are capable of penetrating deeper than the outermost layer, the stratum corneum. This approach provides an advantage in anti-aging formulations because multiple ingredients with various benefits can be delivered in an optimal sequence. For instance, BHA (beta-hydroxy acid) can be released first and exfoliate the skin to create a fresher and cleaner surface for the sub-micron spheres to deposit onto and release their agents. Table 1 shows Salvona’s MultiSal™ product names, the functional ingredients, and the ­applications.

Table 1: Salvona’s products comprised of microencapsulated functional ­ingredients

c. Gel-based encapsulation systems

CylaSphere™ Retinol from BASF, Germany (originally from Coletica, France) are acacia senegal plant-derived microspheres encapsulating 1% retinol. The product claims include usefulness in smoothing, lightening, and whitening applications. It is incorporated into emulsions at 1–10% loading. The composition is a blend of water, butylene glycol, glycine soja (soybean) oil, retinol, carbomer, tocopherol, acacia senegal gum, and propylene glycol alginate. Literature evidence shows higher epidermal residence time from the spheres vs. o/w emulsions containing free retinol, and the determination was made using an in vitro Franz experimental set-up for diffusion of retinol through hairless mouse skin.6 The product is present in Sothy’s Homme Age-Defying Active Care.

d. Porous polymeric systems

One company that is well known for this type of technology is Tagra, which is part of the Elfa Chemical Industries Group. Established in 1998, it is located in Tel Chay, northern Israel. Tagra specializes in developing stabilized active ingredients for the personal care and pharma industries. The approach results in claims of successful protection of more than 40 actives in cosmetics, OTC, and pharma products. The technology is based on a solvent evaporation method of encapsulation to generate particles with average particle size of 40 microns.7 The advantages of the technology are 1) overcoming ingredient and solvent incompatibilities, 2) preventing degradation, 3) retaining ingredient’s activity, 4) prolonged shelf life, and 5) masking odor, color, taste, and feel. The release-on-demand claims are 1) solvent-removing method, 2) CTFA regulations, 3) high loading, and 4) maximum efficacy. Tagravit capsules enable encapsulation of pigments, vitamins, oils, flavonoids, and pharmaceutical ingredients. Table 2-6 shows Tagra’s product names, the functional ingredients, and the applications.

Pigments

Table 2: Tagra’s products comprised of encapsulation of pigments

Vitamins

Table 3: Tagra’s products comprised of encapsulation of vitamins

Oils, essential oils, volatiles

Table 4: Tagra’s products comprised of encapsulation of oils

Related posts:

References – EMERGING STRATEGIES FOR SUSTAINABLE PACKAGING: BALANCING MATERIALS, DESIGN, AND APPEARANCE – METHODS TO ASSESS SKIN BARRIER INTEGRITY: EFFECTS OF CLEANSING PRODUCTS – SUSTAINABILITY & ECO-RESPONSIBILITY – FORMULATING COSMETICS AND PERSONAL CARE PRODUCTS – IMAGING TECHNIQUES AND ANALYSIS FOR QUANTIFICATION OF SKIN APPEARANCE

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