Summary and Key Features
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Delivery systems are intended to maximize performance and provide consumer-perceivable benefits with excellent aesthetic attributes to provide a unique feel and form. They are also intended to enhance the aesthetics of the formulation so that consumers will continue to use the product to achieve maximum benefits.
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Successful delivery systems must consider pH, solubility, compatibility, stability, and preservation.
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Emulsions are the major delivery system and can be divided into two major forms: oil-in-water and water-in-oil.
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Serums, which have become an essential part of the skin care regimen, are thin liquids that can be clear, translucent, or opaque and are usually dispensed from airless pumps or dropper bottles.
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Balms can be a subcategory of emulsion products, but they can also be anhydrous formulations designed to provide specific skin care benefits and, in some cases, to optimize the delivery of an active ingredient. Polymer encapsulation systems can fully isolate and deliver bioactive ingredients working with hydrophobic materials to isolate and selectively deliver ingredients.
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Introduction
The success of efficacious skin care antiaging formulations, sometimes referred to as cosmeceutical products, presents to the cosmetic chemist both challenges and opportunities in developing formulations that deliver consumer-perceived efficacy. These challenges and opportunities have resulted in the development of new and unique formulations that are intended to:
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Be safe and effective topical skin care products
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Address the aesthetic aspects that consumers desire (application, feel, smell, etc.), because if consumers do not like the aesthetics, they will not be inclined to use the product
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Maximize the performance of the product
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Offer the consumer options that provide enhanced aesthetic attributes that make the experience enjoyable
While the formulations are an integral part of the delivery system that are intended to maximize performance and provide consumer-perceivable benefits, the aesthetic attributes, unique feel, and unique form of the formulations are playing an increasing role in consumers’ reasons for choosing the skin care products they are using.
This chapter discusses some of the unique and different formulations that are being developed and are becoming a part of consumers’ skin care regimens.
Vehicles
The primary purpose of the vehicle is to optimize the delivery of the product’s skin care benefits to the consumer. This usually involves providing immediate or short-term benefits, as well as long-term benefits that take 30–60 days to manifest. It is also imperative that the consumer has a positive, if not a pleasurable, experience while using the product so that they continue to use it. While consumers understand that it takes some time for cosmeceutical products to provide the maximum benefits that the formulations are being asked to provide, they also expect an immediate perceived benefit while the short-term and long-term benefits being provided by the product’s bioactive materials (e.g., peptides, botanicals, and retinol) perform their function. All of this is done while ensuring that the ingredients used in the formulations are safe for use and that the formulations are adequately preserved against potential microbial contamination.
The most common and most efficacious vehicle is the emulsion. This category has seen tremendous growth and change with the increased use of different emulsion types, such as silicone-in-water emulsions, water-in-silicone emulsions, and liquid crystal emulsions. The presence of silicone and silicone polymers and elastomers has given consumers a wider choice of feel and form, along with the enhanced provision of skin care benefits.
In the past several years, serums have become an addition to consumers’ skin care regimens. Serums are frequently used as under-eye treatments and to target specific skin care issues such as acne outbursts and hyperpigmentation spots.
As of this writing, we have also seen the introduction of specialty balm products under the category of BB and CC creams, which will be discussed later in this chapter.
While there is a trend toward increased interest in the use of natural ingredients, there is still significant consumer acceptance of products using various silicones and other synthetically derived ingredients because of their benefits and aesthetics.
Another significant factor in the development process is the complex international regulations that are in place regarding the use of ingredients. These regulations must be followed if a company is looking to expand globally with its products. This area could take up a full book on its own.
Let’s review the various product forms that comprise the skin care regimen.
Emulsions
Oil-in-Water Emulsions
The use of silicone, silicone polymers, and synthetic ingredients in these types of formulations, as well as the use of nontraditional emulsifying systems (more naturally based emulsifiers, ethylene oxide [EO]– and pentylene glycol [PEG]–free emulsifiers, and liquid crystal–forming emulsifiers), has created opportunities in the oil-in-water (O/W) emulsion category to offer different aesthetics, viscosity, and emulsion forms to the consumer. The desire to use more skin-friendly emulsifiers that do not disrupt the barrier properties of the skin or emulsifying systems that work in high silicone–based formulations is changing some formulation strategies. The challenge in this area is in making sure the formulations that are developed using these new emulsifying systems are stable and meet the accepted criteria for a stable shelf life.
The choice of ingredients needs to consider the effect on performance as well as aesthetics. Fig. 2.1 shows an O/W emulsion in which the predominant components of the oil phase are a blend of silicones. This emulsion can be modified with the addition of bioactive ingredients such as antioxidants and skin-soothing ingredients. The other aspect of this formulation that is worth noting is the use of an emulsion-stabilizing system (hydroxyethyl acrylate/sodium acryloyldimethyl taurate copolymer squalane polysorbate 60) that can be added at the end or during the processing of the emulsion. This ingredient serves a dual function: it adjusts viscosity and improves emulsion stability. Care must be taken, however, because these emulsion-stabilizing systems can also affect the feel of the product.
Water-in-Oil and Water-in-Silicone Emulsions
Water-in-oil (W/O) and water-in-silicone (W/S) emulsions, sometimes referred to as inverse emulsions, are formulations in which the internal or dispersed phase is a water phase and the oil (or silicone) phase is the continuous or external phase. These emulsions are becoming more popular because of their value in delivering high SPF/UVA sunscreen formulations. Sunscreen formulations are the most valuable antiaging formulations that consumers can use. The challenge in formulating high SPF/UVA sunscreens is in delivering the UV protection benefits within the confines of the aesthetics that consumers want. The formulation from Grant Industries ( Fig. 2.2 ) demonstrates the use of emulsifier systems in a typical BB cream formulation. These systems have become increasingly useful when developing water-resistant sunscreen products and when looking to incorporate more lipophilic (oil-loving) functional materials into formulations that deliver skin care benefits such as barrier protection. The formulation from Momentive ( Fig. 2.3 ) is an example of an anhydrous glycol-in-silicone emulsion that can be used as a delivery system for cosmeceutical actives that have stability issues in water (e.g., ascorbic acid or vitamin C).
Serums
Serums generally are thin liquids that can be clear, translucent, or opaque and are usually dispensed from airless pumps or cosmetically elegant dropper bottles. There is no clear definition of what a serum must contain or look like, and unlike emulsions, which contain two or more phases, serums can be single-phase or multiphase formulations.
The initial serum formulations were developed for use in the eye area to deliver bioactive materials to treat dark circles, bags, fine lines, and wrinkles. They were usually designed to be absorbed quickly so that they could be used under makeup or facial moisturizers. Newer serums have been designed as spot treatments targeting age spots and acne outbreaks, as well as all-over facial serums to enhance the cosmeceutical benefits of bioactive ingredients (e.g., retinol, niacinamide) that are used in the serum formulations or in the facial moisturizer used in conjunction with the serums. The formulation from Grant Industries ( Fig. 2.4 ) demonstrates a serum formulation designed to provide pore refining benefits. This serum is a translucent thin emulsion.
