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The term 'cosmeceutical' has always been controversial, with the lack of a proper definition, its difference from individual cosmetic and pharmaceutical agents, the mechanism, dermatological use, and regulatory issues. This activity aims to provide a suitable definition for an ever-transforming and ever-evolving word which has a history of being measured on various yardsticks for inclusion in the healthcare delivery system in different countries. This activity will also distinguish cosmeceuticals from cosmetics and drugs, the uses of each, general regulatory aspects and highlight the role of the interprofessional team in the appropriate utilization of cosmeceuticals and on educating patients about them. Objectives: Explain the terms cosmeceutical and nutraceutical as well as the broad categories of agents included in each category. Review the regulations, indications, contraindications, and federal drug administration (FDA) approval status of cosmeceutical versus cosmetic versus pharmaceutical and the relevant regulations on the uses, and approval for dermatologic use. Describe the use of specific cosmeceuticals in the treatment and prevention of skin conditions. Summarize how incorporating an interprofessional didactic about cosmeceutical ensures up-to-date knowledge that can be shared with patients. Access free multiple choice questions on this topic.

Cosmeceuticals have undoubtedly taken over the personal care industry across the globe. Despite the prevalent confusion about its definition and scope, it would not be an exaggeration to state that almost 30% to 40% of any dermatologist's prescription count across the world consists of a cosmeceutical. The term was coined in 1984 by Dr. Albert Kligman of the University of Pennsylvania describing a hybrid category of products mid-way on the spectrum of 'cosme'tics and pharma'ceutical.'[1] A cosmeceutical is consensually accepted to exert a 'pharmaceutical therapeutic benefit' but not necessarily a 'biological therapeutic benefit.'[2] For Dr. Kligman, cosmeceutical represented “a topical preparation that is sold as a cosmetic but has performance characteristics that suggest pharmaceutical action.” He coined this term around the crucial time of Kligman's experimentation on the anti-aging effects of tretinoin. The scope of cosmeceuticals has been almost exponentially expanding, e.g., with the discovery of alpha-hydroxy acids for exfoliation and skin rejuvenation, different formulations of topical vitamin C, and an overflowing basket of antioxidants, amongst others. The aptness of the term 'cosmeceutical' gained more ground as it represented a new breed of cosmetic products, which provided effects beyond simple cosmetic enhancement but fell short of qualifying for a drug or pharmaceutical. DEFINITIONS & CONTROVERSIES

Cosmeceuticals have undoubtedly taken over the personal care industry across the globe. Despite the prevalent confusion about its definition and scope, it would not be an exaggeration to state that almost 30% to 40% of any dermatologist's prescription count across the world consists of a cosmeceutical. The term was coined in 1984 by Dr. Albert Kligman of the University of Pennsylvania describing a hybrid category of products mid-way on the spectrum of 'cosme'tics and pharma'ceutical.'[1] A cosmeceutical is consensually accepted to exert a 'pharmaceutical therapeutic benefit' but not necessarily a 'biological therapeutic benefit.'[2] For Dr. Kligman, cosmeceutical represented “a topical preparation that is sold as a cosmetic but has performance characteristics that suggest pharmaceutical action.” He coined this term around the crucial time of Kligman's experimentation on the anti-aging effects of tretinoin. The scope of cosmeceuticals has been almost exponentially expanding, e.g., with the discovery of alpha-hydroxy acids for exfoliation and skin rejuvenation, different formulations of topical vitamin C, and an overflowing basket of antioxidants, amongst others. The aptness of the term 'cosmeceutical' gained more ground as it represented a new breed of cosmetic products, which provided effects beyond simple cosmetic enhancement but fell short of qualifying for a drug or pharmaceutical. DEFINITIONS & CONTROVERSIES The most practical definition of this term may be - a cosmetic product that is purported to have therapeutic action capable of affecting the skin positively beyond the time of its application. Although the term cosmeceutical is steeped in dermatology literature and dominates academic discussions, symposia, and lectures around the world, it is strangely interesting that almost four decades after coining the term, this category of skincare products is still not formally recognized by the United States Food and Drug Administration (US-FDA) or the European Union. This disparity stems from the differentiation between 'cosmetics' and 'drugs' by the Federal Food, Drug, and Cosmetic Act (FD&C Act) based on their intended use and ability to affect the structure and function of the cutis. Both in the United States and the European Union, a drug is defined as "an article intended for the use in the diagnosis, mitigation, treatment or prevention of disease or intended to affect the structure or any function of the body."[3] In contrast, the FD&C Act of 1938 defines cosmetics as "articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractiveness, or altering the appearance" without affecting structure or function.[3] In India, a well-defined Drugs and Cosmetics Act (1940) operates the regulations of cosmetics under the authority of the Central Drugs Standard Control Organization (CDSCO). But CDSCO also recognizes drugs and cosmetics, not cosmeceutical. In a nutshell, it is unfortunate that despite the ubiquitous presence, sale, marketing, and prescription by dermatologists, to date, there is no international consensus. These impact of this deficiency in regulatory nomenclature has far-reaching consequences concerning the essentials of product labeling [prescription or over the counter (OTC)], the stringency of testing protocol, and approval for sale and distribution. In the U.S., for example, in contrast to strict laws for drugs, there is no requirement for manufacturers to demonstrate either safety or efficacy before marketing a product that would otherwise qualify as a cosmeceutical, as is the case for drugs.  The Japanese authorities identify that many skincare products qualify as neither pure drugs nor pure cosmetics in the traditional sense, but a mix of the two, and call them ‘quasi-drugs.’ They permit cosmetics to contain pharmacologically active ingredients, provided that the medicinal effects are mild and the products'safety has been demonstrated. The legal jargon or lack thereof has left a lot of room for ambiguities and ad hoc interpretations resulting in skewed treatment of certain products by different regulatory authorities. The following example exemplifies the ambiguity; the following agents are regulated as drugs in the U.S., and as cosmetics in Europe: antiperspirants, anti-dandruff shampoos, and sunscreens.

The most practical definition of this term may be - a cosmetic product that is purported to have therapeutic action capable of affecting the skin positively beyond the time of its application. Although the term cosmeceutical is steeped in dermatology literature and dominates academic discussions, symposia, and lectures around the world, it is strangely interesting that almost four decades after coining the term, this category of skincare products is still not formally recognized by the United States Food and Drug Administration (US-FDA) or the European Union. This disparity stems from the differentiation between 'cosmetics' and 'drugs' by the Federal Food, Drug, and Cosmetic Act (FD&C Act) based on their intended use and ability to affect the structure and function of the cutis. Both in the United States and the European Union, a drug is defined as "an article intended for the use in the diagnosis, mitigation, treatment or prevention of disease or intended to affect the structure or any function of the body."[3] In contrast, the FD&C Act of 1938 defines cosmetics as "articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractiveness, or altering the appearance" without affecting structure or function.[3] In India, a well-defined Drugs and Cosmetics Act (1940) operates the regulations of cosmetics under the authority of the Central Drugs Standard Control Organization (CDSCO). But CDSCO also recognizes drugs and cosmetics, not cosmeceutical. In a nutshell, it is unfortunate that despite the ubiquitous presence, sale, marketing, and prescription by dermatologists, to date, there is no international consensus. These impact of this deficiency in regulatory nomenclature has far-reaching consequences concerning the essentials of product labeling [prescription or over the counter (OTC)], the stringency of testing protocol, and approval for sale and distribution. In the U.S., for example, in contrast to strict laws for drugs, there is no requirement for manufacturers to demonstrate either safety or efficacy before marketing a product that would otherwise qualify as a cosmeceutical, as is the case for drugs.  The Japanese authorities identify that many skincare products qualify as neither pure drugs nor pure cosmetics in the traditional sense, but a mix of the two, and call them ‘quasi-drugs.’ They permit cosmetics to contain pharmacologically active ingredients, provided that the medicinal effects are mild and the products'safety has been demonstrated. The legal jargon or lack thereof has left a lot of room for ambiguities and ad hoc interpretations resulting in skewed treatment of certain products by different regulatory authorities. The following example exemplifies the ambiguity; the following agents are regulated as drugs in the U.S., and as cosmetics in Europe: antiperspirants, anti-dandruff shampoos, and sunscreens. Currently, cosmeceuticals are a segregated subclass within the domain of a cosmetic or drug. In Europe and Japan, cosmeceuticals are a subclass of cosmetics; however, in the US, cosmeceuticals can only be considered as a subclass of drugs.

The most practical definition of this term may be - a cosmetic product that is purported to have therapeutic action capable of affecting the skin positively beyond the time of its application. Although the term cosmeceutical is steeped in dermatology literature and dominates academic discussions, symposia, and lectures around the world, it is strangely interesting that almost four decades after coining the term, this category of skincare products is still not formally recognized by the United States Food and Drug Administration (US-FDA) or the European Union. This disparity stems from the differentiation between 'cosmetics' and 'drugs' by the Federal Food, Drug, and Cosmetic Act (FD&C Act) based on their intended use and ability to affect the structure and function of the cutis. Both in the United States and the European Union, a drug is defined as "an article intended for the use in the diagnosis, mitigation, treatment or prevention of disease or intended to affect the structure or any function of the body."[3] In contrast, the FD&C Act of 1938 defines cosmetics as "articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractiveness, or altering the appearance" without affecting structure or function.[3] In India, a well-defined Drugs and Cosmetics Act (1940) operates the regulations of cosmetics under the authority of the Central Drugs Standard Control Organization (CDSCO). But CDSCO also recognizes drugs and cosmetics, not cosmeceutical. In a nutshell, it is unfortunate that despite the ubiquitous presence, sale, marketing, and prescription by dermatologists, to date, there is no international consensus. These impact of this deficiency in regulatory nomenclature has far-reaching consequences concerning the essentials of product labeling [prescription or over the counter (OTC)], the stringency of testing protocol, and approval for sale and distribution. In the U.S., for example, in contrast to strict laws for drugs, there is no requirement for manufacturers to demonstrate either safety or efficacy before marketing a product that would otherwise qualify as a cosmeceutical, as is the case for drugs.  The Japanese authorities identify that many skincare products qualify as neither pure drugs nor pure cosmetics in the traditional sense, but a mix of the two, and call them ‘quasi-drugs.’ They permit cosmetics to contain pharmacologically active ingredients, provided that the medicinal effects are mild and the products'safety has been demonstrated. The legal jargon or lack thereof has left a lot of room for ambiguities and ad hoc interpretations resulting in skewed treatment of certain products by different regulatory authorities. The following example exemplifies the ambiguity; the following agents are regulated as drugs in the U.S., and as cosmetics in Europe: antiperspirants, anti-dandruff shampoos, and sunscreens. Currently, cosmeceuticals are a segregated subclass within the domain of a cosmetic or drug. In Europe and Japan, cosmeceuticals are a subclass of cosmetics; however, in the US, cosmeceuticals can only be considered as a subclass of drugs. REGULATION & LICENSING OF COSMECEUTICALS

The most practical definition of this term may be - a cosmetic product that is purported to have therapeutic action capable of affecting the skin positively beyond the time of its application. Although the term cosmeceutical is steeped in dermatology literature and dominates academic discussions, symposia, and lectures around the world, it is strangely interesting that almost four decades after coining the term, this category of skincare products is still not formally recognized by the United States Food and Drug Administration (US-FDA) or the European Union. This disparity stems from the differentiation between 'cosmetics' and 'drugs' by the Federal Food, Drug, and Cosmetic Act (FD&C Act) based on their intended use and ability to affect the structure and function of the cutis. Both in the United States and the European Union, a drug is defined as "an article intended for the use in the diagnosis, mitigation, treatment or prevention of disease or intended to affect the structure or any function of the body."[3] In contrast, the FD&C Act of 1938 defines cosmetics as "articles intended to be rubbed, poured, sprinkled, or sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractiveness, or altering the appearance" without affecting structure or function.[3] In India, a well-defined Drugs and Cosmetics Act (1940) operates the regulations of cosmetics under the authority of the Central Drugs Standard Control Organization (CDSCO). But CDSCO also recognizes drugs and cosmetics, not cosmeceutical. In a nutshell, it is unfortunate that despite the ubiquitous presence, sale, marketing, and prescription by dermatologists, to date, there is no international consensus. These impact of this deficiency in regulatory nomenclature has far-reaching consequences concerning the essentials of product labeling [prescription or over the counter (OTC)], the stringency of testing protocol, and approval for sale and distribution. In the U.S., for example, in contrast to strict laws for drugs, there is no requirement for manufacturers to demonstrate either safety or efficacy before marketing a product that would otherwise qualify as a cosmeceutical, as is the case for drugs.  The Japanese authorities identify that many skincare products qualify as neither pure drugs nor pure cosmetics in the traditional sense, but a mix of the two, and call them ‘quasi-drugs.’ They permit cosmetics to contain pharmacologically active ingredients, provided that the medicinal effects are mild and the products'safety has been demonstrated. The legal jargon or lack thereof has left a lot of room for ambiguities and ad hoc interpretations resulting in skewed treatment of certain products by different regulatory authorities. The following example exemplifies the ambiguity; the following agents are regulated as drugs in the U.S., and as cosmetics in Europe: antiperspirants, anti-dandruff shampoos, and sunscreens. Currently, cosmeceuticals are a segregated subclass within the domain of a cosmetic or drug. In Europe and Japan, cosmeceuticals are a subclass of cosmetics; however, in the US, cosmeceuticals can only be considered as a subclass of drugs. REGULATION & LICENSING OF COSMECEUTICALS Ideally, the registration protocol for a cosmeceutical should not be as complicated as for drugs. Of course, as per Good Clinical Practices [GCP], clinical studies with adequate power should be essential to demonstrate the intended activity of the cosmeceutical for treatment of the particular minor skin disorder or 'condition,' and there must be an assurance that safety requirements are optimal and that there are no expected side effects.[4] In the United States, this implies that a subclass of drugs (cosmeceuticals) are registered similarly as over-the-counter products.[5] The legendary legal controversy on the regulatory labeling of topical minoxidil for male pattern baldness resulted in the assertion that the pharmaceutical activity of a product, rather than the condition it is intended to modify (normal vs. diseased skin), determines whether it is a cosmetic or a drug.[3]

Ideally, the registration protocol for a cosmeceutical should not be as complicated as for drugs. Of course, as per Good Clinical Practices [GCP], clinical studies with adequate power should be essential to demonstrate the intended activity of the cosmeceutical for treatment of the particular minor skin disorder or 'condition,' and there must be an assurance that safety requirements are optimal and that there are no expected side effects.[4] In the United States, this implies that a subclass of drugs (cosmeceuticals) are registered similarly as over-the-counter products.[5] The legendary legal controversy on the regulatory labeling of topical minoxidil for male pattern baldness resulted in the assertion that the pharmaceutical activity of a product, rather than the condition it is intended to modify (normal vs. diseased skin), determines whether it is a cosmetic or a drug.[3] CONCENTRATION OF ACTIVE INGREDIENT & LABELLING The issue becomes more convoluted when the basis of the drug vs. cosmetics differentiation centers on the concentration of the active ingredient. At the moment, sunscreen-containing products are classified as cosmetics, provided the sun protection factor (SPF) is below 4,[6] while high SPF sunscreens still have approval for sale over the counter (OTC). Interestingly, a recent proposal by FDA entails classifying any sunscreen that specifies SPF as a drug.[7]  Similarly, while the FDA regards lactic acid at 12% as a drug, the same ingredient in lower concentrations is permitted in cosmetics. Regrettably, regulations appear to completely ignore the effect of vehicles, stabilizers, and other excipients. WORKING DEFINITION For this activity, backed by a plethora of literature on the issue, a cosmeceutical may be characterized as: The product has pharmaceutical activity and is usable on normal or near-normal skin. The product should possess a defined benefit for minor skin disorders (cosmetic indication). The product possesses a very low-risk profile. WHAT'S A NUTRACEUTICAL?

For this activity, backed by a plethora of literature on the issue, a cosmeceutical may be characterized as: The product has pharmaceutical activity and is usable on normal or near-normal skin. The product should possess a defined benefit for minor skin disorders (cosmetic indication). The product possesses a very low-risk profile. WHAT'S A NUTRACEUTICAL? The term “nutraceutical” was coined in 1989 by Stephen De Felice from “nutrition” and “pharmaceutical.”[8] Another definition by Health Canada states, “a product prepared from foods, but sold in the form of pills, or powder (potions) or other medicinal forms, not usually associated with foods.”[9] Nutraceuticals may be sourced from natural herbs, food industry, dietary supplements market, and the pharmaceutical industry, and now trending towards genetically engineered “designer” foods as well. Although nutraceuticals cover most of the therapeutic areas such as anti-arthritic, digestive problems, prophylaxis, and treatment for cancers, lipid and sugar control, osteoporosis, blood pressure, and depression among others, in context of skin, one can grossly regard a nutraceutical an orally consumed product with cosmeceutical benefits. COSMECEUTICALS INDICATIONS [10] [11] Anti-aging in general Treatment of photomelanosis and photo tanning Treatment of pigmentation-related disorders like melasma or freckles Rhytide reduction Anti-inflammatory Fat loss Hair growth Hair fall prevention Maintenance of skin tone and clarity of complexion

INDICATION/CLASSIFICATION OF COSMECEUTICALS There is no single/accepted classification of cosmeceuticals. Broadly, they fall into categories based on their chief etiological indication, i.e., the condition for which a person would use them, or based on their source or biochemical structure. COSMECEUTICAL CATEGORIES AS PER THEIR CHIEF INDICATION BASED ON ETIOLOGY OF THE TARGET CONDITION: 1) Skin lightening or depigmenting 2) Sunscreens 3) Moisturizing agents 4) Anti-wrinkle/aging 5) Scar-reducing 6) Antioxidants 7) Hair strengthening 8) Specific disorder-related, e.g., acne, rosacea, melasma 9) Miscellaneous The following list enumerates a large number of commonly used and prescribed cosmeceuticals and nutraceuticals.[12] The full list is too exhaustive and beyond the scope of this activity. Alpha-lipoic acid, oral Coenzyme Q10, oral Vitamin B-complex, oral Vitamin C, oral and topical Vitamin E, topical and oral Hydroquinone, topical Alpha and beta hydroxy acids, topical Polyunsaturated fatty acids, oral Peptides, topical Retinoids, oral Retinaldehyde, topical Retinal esters, topical Retinol, topical Comfrey, topical Feverfew, topical Jojoba oil, topical Licorice topical Pune bark extract and topical Rose, topical Turmeric, topical and oral Milk thistle, topical Lavender, topical Grapeseed, oral Green tea, oral Lycopene, oral Pomegranate: oral Arbutin: topical Kojic acid: topical Soya: oral and topical Aloe vera, topical and oral Chamomile: oral Caffeine: oral and topical Polypodium leucotomos, oral Glutathione, oral, parenteral, topical Phytosterols, oral and topical Proanthocyanidin, oral Panthenol, topical Ceramides, topical Zinc, topical and oral Licorice plant [glycyrrhiza] - glabridin Tyrowhite, topical Ellagic acid, topical Sunscreen ingredients Idebenone Resveratrol Hyaluronic acid Glucosamine Azelaic acid Niacinamide Allium cepa Allantoin Marine protein supplements (MPS)

THE EXPANDING GLOBAL COSMECEUTICAL MARKET & TRENDS The desire to look good, younger, toned, and healthy has caught on across the global population in a big way. According to Euromonitor International, the 2015 global retail sales of natural products-based cosmeceuticals were US$2.98 billion, with this segment showing a 4% compound annual growth rate (CAGR) during the previous five years. According to the study conducted by Indian Cosmetic Sector Analysis, the cosmetic market is around INR 356 billion. The  Indian beauty and cosmetic market have been showing a consistent growth between 15 to 20% per annum. Women remain the top consumers, although the use of cosmeceuticals by men is steadily increasing. Two major factors have contributed to the rising trend in this market - media exposure with attractive and catchy advertising by manufacturing companies, and the corporate dressing culture, which was commonplace in the west, but now evolving quickly in the Asia-Pacific region as well. Lastly, the improved buying capacity of consumers also has a substantial contribution to this phenomenon. Concomitant with the growth, there has also been a surge of development and employment of novel and innovative technologies for producing safer and more effective cosmeceuticals. Nanotechnology, penetration enhancers, stabilizers, and special excipients are increasing in use.[13]  Leading companies are developing formulations that can be conveniently tested on 3D bioprinted live human tissue, obviating the need for time- and cost-consuming elaborate animal and human trials.[14]

The evaluation of the biological characteristics of the active ingredients in cosmeceuticals, especially for organic sources like marine extracts, depends on the selection of an appropriate EXTRACTION process.[21]  The quality of the end product depends majorly on a properly conceived and executed extraction technique. Of course, other factors that are of vital importance in determining the end product include various physicochemical properties of the source material, the type, and concentration of the extracting solvent, the ambient pH, temperature, and pressure conditions of the extraction methodology amongst others. The extraction techniques divide into conventional or classical, and the novel or modern approaches. CONVENTIONAL EXTRACTION METHODS [21]: (1) Hydro-distillation (2) Soxhlet extraction (3) Maceration (4) Percolation (5) Infusion (6) Decoction (7) Hot continuous extraction Of the above, Soxhlet extraction has been the conventional methodology, especially for plant/marine-derived sources. However, the need for pre-digestion by acids with consequent time consumption is a major limiting factor. Other limitations of the above-mentioned conventional extraction techniques include the requirement of high purity solvents, low extraction yield, decomposition of thermolabile ingredients, and long extraction periods.  The novel non-conventional (modern) extraction techniques were developed to overcome some/most of these limitations. Further, since modern technologies comply with the U.S. Environmental Protection Agency (EPA) standards, they are considered eco-friendly or 'green.'   A detailed discussion of each of the modern technologies and evaluation methodologies for individual cosmeceuticals is beyond the scope of this CME chapter. Thus interested readers are advised to refer to comprehensive articles authored on this subject.[21][22] MODERN EXTRACTION METHODS [21]: (1) Superficial-fluid extraction (SFE) (2) Pressurized-liquid extraction (PLE) (3) Enzyme-assisted extraction (EAE) (4) Microwave-assisted  extraction (MAE) EVALUATION OF COSMECEUTICALS The father of 'cosmeceuticals,' Dr. Albert Kligman, suggested three crucial questions to be answered to ascertain the claimed physiological/biological/therapeutic effect of a cosmeceutical product [23][24]:

(2) Pressurized-liquid extraction (PLE) (3) Enzyme-assisted extraction (EAE) (4) Microwave-assisted  extraction (MAE) EVALUATION OF COSMECEUTICALS The father of 'cosmeceuticals,' Dr. Albert Kligman, suggested three crucial questions to be answered to ascertain the claimed physiological/biological/therapeutic effect of a cosmeceutical product [23][24]: Is the active ingredient able to penetrate the stratum corneum (SC) and be deliverable in sufficient concentrations to its intended skin target over a time course consistent with its mechanism of action? Does the active ingredient possess a known specific biochemical mechanism of action in the target cell or tissue in human skin? Are there published, double-blind, peer-reviewed, placebo-controlled, statistically significant, clinical trials to substantiate the efficacy claims? PENETRATION ACROSS STRATUM CORNEUM(SC): Penetration of ingredients across the SC, a robust barrier to prevent transepidermal water loss (TEWL), is the first hurdle to be overcome. Proteins, peptides, sugars, and nucleic acids with molecular weights >1000kDa and highly charged molecules find it difficult to penetrate an intact SC. The penetrating behavior of an active ingredient can undergo evaluation: (1) in vitro (2) ex vivo, and (3) in vivo Basic Principle - The published human stratum corneum permeability coefficient (Kp, often expressed as log Kp) has been used for ages by investigators to develop models to predict skin permeability.[25] The most commonly used device for in vitro diffusion and for determining penetration through skin consists of the Franz-type diffusion cell or its modifications.[25] For in vitro studies, this barrier can consist of an artificial skin construct (ASC). Ex vivo studies employ either animal skin, human cadaver skin, or bovine udder skin (BUS) as the barrier.[26]

Basic Principle - The published human stratum corneum permeability coefficient (Kp, often expressed as log Kp) has been used for ages by investigators to develop models to predict skin permeability.[25] The most commonly used device for in vitro diffusion and for determining penetration through skin consists of the Franz-type diffusion cell or its modifications.[25] For in vitro studies, this barrier can consist of an artificial skin construct (ASC). Ex vivo studies employ either animal skin, human cadaver skin, or bovine udder skin (BUS) as the barrier.[26] For human in vivo penetration studies, tape stripping, or advanced spectroscopic methods, e.g., ATR (attenuated total reflection) spectroscopy is an option. A more advanced in vivo technique is microdialysis.[27] Some newer approaches include - principal components analysis (PCA), probabilistic analyses, fuzzy modeling, artificial neural network (ANN) modeling, and biopartitioning micellar chromatography, amongst others.[25] The development of newer carrier systems and techniques with nanoparticulation, ionto- and electroporation, liposomes, etc. have not only revolutionized the approach to enhance smooth percutaneous absorption of desirable ingredients but have correspondingly lead to the development of more sophisticated evaluation techniques. BIOENGINEERING TESTS FOR DRUG TARGET IDENTIFICATION Various bioengineering techniques have been employed to determine the specific drug target within the skin. Some of these include[28][29][30][31]: (1) Evaporimetry - for measurement of cosmeceutical impact on reducing TEWL (2) Corneometry - conductivity of skin to a low electric current to evaluate skin water content (3) Profilometry - to evaluate skin texture and improvement in skin elasticity and fine wrinkles (4) Laser Doppler flowmetry - to evaluate erythema indices using the Doppler effect to measure the cutaneous blood flow (5) A-scan ultrasound imaging - to ascertain the 'skin thickening' claims of cosmeceuticals CLINICAL TRIALS FOR SUBSTANTIATION OF CLAIMS

(3) Profilometry - to evaluate skin texture and improvement in skin elasticity and fine wrinkles (4) Laser Doppler flowmetry - to evaluate erythema indices using the Doppler effect to measure the cutaneous blood flow (5) A-scan ultrasound imaging - to ascertain the 'skin thickening' claims of cosmeceuticals CLINICAL TRIALS FOR SUBSTANTIATION OF CLAIMS This is perhaps the most important aspect of evaluation, but it is not an entity in isolation, rather an amalgamation of basic, translational, and clinical trial data on a cosmeceutical. Ideally, clinical trials should prefer noninvasive instruments to measure parameters such as TEWL, corneometry, skin elasticity, colorimetry, profilometry, and other techniques to approve or disprove efficacy claims. Pre-treatment and post-treatment photography is essential but not adequate in isolation owing to pitfalls in standardized clinical photography. Further, the study design should include a large cohort as feasible, be controllable through a placebo, or another entity with well-established effects. Randomization, statistical analyses, and well-defined objective outcome measures are also criteria. The traditional way of histology to demonstrate the effects of a product is ideal but suffers from logistic issues. In contrast, dermoscopy and/or confocal microscopy are novel and validated tools for better assessment than gross photography and are preferred over histology by study subjects and/or volunteers owing to their non-invasive trait.[32]

Cosmaceuticals have been used in a variety of therapeutic indications like[33][34]: 1) Skin lightening or depigmenting 2) Sunscreens 3) Moisturization 4) Anti-wrinkle/aging effects 5) Scar-reduction 6) Antioxidants 7) Hair strengthening, hair fall arrest, hair growth stimulation, textural hair improvement 8) Treatment of specific disorders, e.g., acne, rosacea, melasma 9) Miscellaneous uses

Atopic dermatitis Contact dermatitis Drug eruption Erythema infectiosum Erythema multiforme Folliculitis Guttate psoriasis Insect bites Keratosis pilaris Nummular eczema Tinea corporis Urticaria

Although there is a relative lack of patient studies and trials (primarily stemming from the definition-related issues of regulatory authorities), attempts are being actively pursued to draft well-designed and controlled trials to compare the safety and efficacy of various cosmeceuticals and their constituents for specific indications.[35]

It is not possible to prognosticate in general, the outcome of a particular skin issue amenable to improvement with cosmeceuticals. Every skin has different reactivity, response patterns, and a tendency to develop adverse effects to both pharmaceutical topicals as well as cosmeceuticals. The prognosis after recommended use of cosmeceutical(s) for melasma, e.g., would depend upon the: (1) Disease characteristics - Depth of melasma, the activity of melanocytes, factors (like hormonal pills) that may antagonize the effect of cosmeceuticals (2) Patient factors - Skin sensitivity and tolerance to the cosmeceutical, compliance, and adherence to treatment, concomitant meticulous use of sun protection, affordability to maintain the long-term effect, etc. (3) Cosmeceutical factors - quality, cutaneous bioequivalence of brands, cost, effect, tolerance, the possibility of long-term adverse effects, etc. Thus, the use of cosmeceuticals requires careful individualization in each patient based on all the above factors. Aids like dermoscopy may aid in the preferential selection of a particular cosmeceutical based on the findings, e.g., melasma showing brown pigmented structures may be amenable to short term use of moderate-strength cosmeceuticals, while stronger treatment may be necessary for deep melasma.[44] A de novo melasma with prominent vascular changes may improve more with tranexamic acid-based preparations instead of hydroquinone.

Although complications can be severe like anaphylactic shock, burns, PIH, or milder and transient like irritant dermatitis, contact allergic dermatitis etc.,  by and large the short-term complications with most of the cosmeceuticals are rare, provided they are used in moderation and as per the prescribing physician's advice with essential precautions followed by the patients.

1) The patient must be informed that these are not drugs per se, and these cosmeceuticals are not a substitute for pharmaceutical-grade dermatological topicals. As a corollary, the time taken for improvement may be more. 2) A very common issue that has become daunting for a practicing dermatologist is that the patient seeking improvement in his/her skin texture/tone/pigmentation/hair loss etc. often approaches the dermatologist enquiring about branded cosmeceuticals that they have been using in the past. The dermatologist should make an attempt to verify the contents of the creams, lotions, and other products being used by the patient, and allow or stop their use depending on the patient's condition, tolerance, and the impact of them being in addition to the planned topicals to be prescribed. A cost factor assumes importance here since the majority of cosmeceuticals are not inexpensive. Thus the treating dermatologist should prescribe cost-effective topicals and have a duration in mind for which it should/can be used. The cosmeceutical may have to be changed depending on the improvement or lack thereof, and if any concomitant drugs (like oral isotretinoin) or physical procedures (peels/laser toning) are planned. 3) There is another facet to the cost-related aspect of cosmeceuticals - Patients often insist on continuing to use 'expensive' skin-care products 'gifted' or 'bought' by them It is prudent to explain to the patient that in your opinion, what will help and what may not. 4) Similarly, often, patients ascribe a new problem, e.g., acneiform eruption to the prescribed cosmeceutical. If the clinician is convinced that this cannot be the result of the prescribed topical, counsel, and observe. If the issue persists or worsens, it is advisable to stop all applications and consider doing a patch test. In patients with known sensitive skin, always advise any new topical to be first tested as a patch over a small area of the face or away from the face for 2 to 3 days, and if tolerated, then only go ahead with the therapy. Short contact therapy has been found very useful in certain situations, especially with topical retinoids and AHA-based lotions. The patient with sensitive skin should be advised to start with short duration exposure (5 to 15 min) followed by rinse off and generous use of a moisturizer.

4) Similarly, often, patients ascribe a new problem, e.g., acneiform eruption to the prescribed cosmeceutical. If the clinician is convinced that this cannot be the result of the prescribed topical, counsel, and observe. If the issue persists or worsens, it is advisable to stop all applications and consider doing a patch test. In patients with known sensitive skin, always advise any new topical to be first tested as a patch over a small area of the face or away from the face for 2 to 3 days, and if tolerated, then only go ahead with the therapy. Short contact therapy has been found very useful in certain situations, especially with topical retinoids and AHA-based lotions. The patient with sensitive skin should be advised to start with short duration exposure (5 to 15 min) followed by rinse off and generous use of a moisturizer. 5) Patient compliance - Checking for patient's compliance of using all the prescribed medicines is essential on each visit. Often patients apply retinoids religiously at night but forget to use the sunscreen in the day time as advised. This is a common reason for otherwise unexplainable reactions like redness, aggravated by sun exposure. 6) Undisclosed applications/parlor procedures - The clinician must determine (especially with relatively stronger agents like retinoids) that the patient is not using additional undisclosed skincare products. These agents can include astringents, toners, SA-based face-washes, or taking parlor treatments like facials, bleaching, 'cleansing' etc. since the latter may result in an unwanted complication that the patient often tends to blame on the doctor's prescribed topical instead of his/her own 'mild' skincare products.

The healthcare industry is becoming increasingly commercialized. New, untested molecules or those with a very weak level of evidence receive aggressive promotion. This industrial behavior can affect the patients (through product advertisements on TV and social media) as well as dermatologists (tall claims by medical reps). While there is no denying that cosmeceuticals constitute possibly over 40% of a specialist's prescription, the dermatologist should exercise great caution before endorsing a product. Attempt to search for the highest level of evidence published and safety-associated trials on a few patients with consent should be the approach towards a newly launched cosmeceutical. Members of the healthcare team must ask about the patient's concomitant treatment, including unrevealed home-based therapies (which often includes irritants) such as face-masks, toners, astringents, and most dreaded, steroidal creams to ensure best and safe outcome with treatment. To ensure public safety, an interprofessional team that includes a pharmacist, primary care provider, and nurse practitioner should educate patients about the benefits/harms of a cosmeceutical. Further, the cost implications of long term use for maintenance should be discussed at some point in time during the therapeutic regime. The patient should always receive information about alternative or adjuvant treatment options, whether drugs/physical procedures or injectables. Finally, patients should understand about the existence of fake, counterfeit, and bogus cosmeceuticals on the market. All members of the interprofessional team, from the family physician (including NPs and PAs), the dermatologist, the nursing staff, and the pharmacist, need to have a thorough understanding of these agents. This knowledge will permit team members to determine which agents the patient may be using (since many of them are available over the counter), and communicate with each other to ensure minimal adverse events or interactions with other cosmeceuticals or even actual medications. With each member weighing in and communicating across disciplines, the interprofessional team can better achieve optimal results. Specialty care dermatology and plastic surgery nurses educate and monitor patients, providing feedback to team members. Pharmacists check for drug-drug interactions and also provide education. [Level V]

All members of the interprofessional team, from the family physician (including NPs and PAs), the dermatologist, the nursing staff, and the pharmacist, need to have a thorough understanding of these agents. This knowledge will permit team members to determine which agents the patient may be using (since many of them are available over the counter), and communicate with each other to ensure minimal adverse events or interactions with other cosmeceuticals or even actual medications. With each member weighing in and communicating across disciplines, the interprofessional team can better achieve optimal results. Specialty care dermatology and plastic surgery nurses educate and monitor patients, providing feedback to team members. Pharmacists check for drug-drug interactions and also provide education. [Level V] The healthcare industry needs to take a proper judgment on the judicious use of these agents, which may qualify as drugs. Eventually, their efficacy must be tested. Also, their potency should be compared to other drugs before we start prescribing them as dermatologists and physicians till then, research needs to be increased, and patient education is a must. Lastly, in the current era of social media and internet serving as sources of primary-skin-care for many patients, dispelling the myths and tall claims sourced from these has become an essential duty of the dermatologist. Remember, the dermatologist is the doctor. The patient lured by the gentlemen pickpockets of social media are innocent and often amenable to transformation with proper counseling. But this requires patience on behalf of the doctor as much as the patient himself/herself.