Cosmeceutical Formulation Considerations

Introduction

The success of efficacious skin care ‘antiaging’ formulations, commonly referred to as ‘cosmeceutical’ products, presents the cosmetic chemist tremendous 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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  address the aesthetic aspects that consumers desire (application, feel, smell, etc.)

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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 systems that are intended to maximize performance and provide consumer-perceivable benefits, the aesthetic attributes, unique feel and unique forms, are an increasing factor that consumers are using as a reason to choose their skin care products.

This chapter discusses some of the unique and different formulations that are being developed and are becoming a part of the skin care regimens.

Vehicles

The primary purpose of the vehicle is to optimize the delivery of ‘cosmeceutical’ benefits to the consumer. These usually involve 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 products so they continue to use them. It is the continuous use of ‘cosmeceutical’ products that are essential to getting the maximum benefits that are to be provided. All this is done while insuring that the formulations are safe for use as well as effectively preserved against potential microbial contamination.

The most common, and still the 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, liquid crystal emulsions, etc. The presence of silicone and silicone polymers and elastomers has allowed the consumers a wider choice of feels and forms to choose from when selecting the skin care products.

In the past several years we have seen an increased use of a category of products called ‘serums’. They have become an addition to the skin care regimen and provide targeted specific treatment elements.

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 lot of publicity about the increased use of ‘natural’ ingredients, consumers have decided, by their purchasing choices, that formulations using various silicones are the products of choice for aesthetics.

Another significant factor in the development process is the complex international regulations that are in place regarding the use of ingredients that must be followed if a company is looking to expand the global availability of their 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 increased use of silicone and silicone polymers in these types of formulations, as well as the use of nontraditional emulsifying systems (more ‘naturally’ based emulsifiers, EO- and pentylene glycol (PEG)-free emulsifiers and liquid crystal forming emulsifiers) has opened up the opportunities in the oil-in-water (O/W) emulsion category to offer different feels and 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 are changing some formulation strategies. The challenge in this area is making sure that the formulations that are developed using these new emulsifying systems are stable formulations and meet the accepted criteria for shelf life.

The choice of ingredients needs to consider the effect on performance as well as aesthetics. Figure 2.1 is 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 – antioxidants and skin-soothing ingredients. The other aspect of this formulation that is worth noting is the use of an emulsion-stabilizing system that can be added at the end. This ingredient serves a dual function – adjusting viscosity and improving 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. While still much less popular than O/W emulsions, recent advances in silicone-based emulsifier systems have caused an increase use of these types of formulation. The formulation from Grant Industries ( Fig. 2.2 ) demonstrates the use of these newer emulsifier systems in a typical ‘BB’ cream formulation. They 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’ emulsion that can be used as a delivery system for cosmeceutical ‘actives’ that have stability issues in water (i.e. ascorbic acid – vitamin C).

Serums

Serums are generally thin liquids that can be clear, translucent or opaque and are generally 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 quick absorbing so they can be used under makeup or facial moisturizers. Newer serums have been designed as spot treatments for ‘age spots’, ‘acne outbreaks’ as well as all-over facial serums to enhance the cosmeceutical benefits of bioactive ingredients that are used both in the serum formulations or 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.