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What’s Important?

  1. Cleanser and moisturizer choices affect the efficacy of skincare regimens.

  2. Product efficacy is affected by what products are used before and after application.

  3. Incidence of side effects is influenced by the skincare routine order.

What’s New?

  1. Hyaluronic acid and fatty acids affect penetration of other ingredients.

  2. There are three paths of penetration into the skin.

  3. Identifying how much of each type of skincare product to use.

What’s Coming?

  1. Liposomes and other penetration enhancers are constantly being developed.

  2. Software that can be used to generate science-based skincare regimens.

There are several factors to consider when designing a skincare routine for your patients. The goal is to achieve the greatest efficacy with the lowest level of side effects. The best skincare routines will not work if patients do not follow advice; therefore, it is critical to design a regimen that suits the patient’s lifestyle and budget. Chapter 33 (Choosing Skincare Products) discusses how to choose which skincare products to retail in your practice and Chapter 34 (Skincare Retail in a Medical Setting) explains how best to retail them in your practice. This chapter will discuss what should be considered when designing a skincare routine for your patients.

Topical products should be applied in a particular order to maximize efficacy. This is necessary because cosmeceutical ingredients interact with each other thereby affecting stability, activity, solubility, and penetration. Environmental influences such as temperature, water type, presence of pollution, skin pH, humidity, and the microbiome will influence the efficacy of skincare products. Such chemical phenomena should be considered when developing the order of products for a skincare regimen. Some ingredients are more likely to interact with other ingredients, such as benzoyl peroxide, retinoids, hydroxy acids, hydroquinone, vitamin C, and peptides. The most important issue to keep in mind when designing a skincare regimen is how much of the cosmeceutical ingredient will penetrate the skin without inactivating other important active components. The trick is to design the skincare regimen properly to maximize stability and penetration.


Most of the information we have on getting topical ingredients into the dermis is in the drug delivery literature. Topically applied cosmeceutical ingredients and drugs can penetrate the skin in three ways:

  1. Transcellular route1: involves entering the skin by directly passing through the lamellar lipid layers and the cell membranes and moving across the hydrophilic keratin-enriched cytoplasm of stratum corneum (SC) keratinocytes. In this route, substances must cross both lipophilic and hydrophilic structures.2

  2. Intracellular or paracellular route: involves passing between the intercellular spaces between keratinocytes.

  3. Appendageal route: hydrophilic compounds and macromolecules may pass through the hair follicle and/or sweat gland to enter the dermis. This route is affected by anatomical location because of regional diversity in the number of hair follicles.3

Penetration of ingredients into the skin is based on multiple ...

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