Adapalene biochemistry and the evolution of a new topical retinoid for treatment of acne

A Comprehensive Review of the Strategies to Reduce Retinoid-Induced Skin Irritation in Topical Formulation

Currently, retinoids are known for their abundant benefits to skin health, ranging from reducing signs of aging and decreasing hyperpigmentation to treating acne. However, it cannot be denied that there are various side effects associated with the use of retinoids on the skin, one of which is irritation. Several approaches can be employed to minimize the irritation caused by retinoids. This review article discusses topical retinoid formulation technology strategies to reduce skin irritation effects. The methodology used in this study is a literature review of 21 reference journals. The sources used in compiling this review are from PubMed, Scopus, ScienceDirect, and MEDLINE. The findings obtained indicate that the following methods can be used to lessen retinoid-induced irritation in topical formulations: developing drug delivery systems in the formulation, such as encapsulating retinoids, transforming retinoids into nanoparticles, forming complexes (e.g., with cyclodextrin), and binding retinoids with carriers (e.g., polymers, NLC, SLN), adding ingredients with anti-irritation activity, skin barrier improvement, and increased skin hydration to retinoid formulations (e.g., combinations of glucosamine, trehalose, ectoine, sucralfate, omega-9, and 4-t-butylcyclohexanol, addition of ethanolic bark extract of Alstonia scholaris R. Br).

Screening of Adapalene Microsponges Fabrication Parameters with Insight on the In vitro Biological Effectiveness

PURPOSE

The objective of the present study was to scrutinize the microsponges (MS) as a carrier system using Adapalene (ADA) as a model drug.

METHODS

Data modelling was implemented using Plackett-Burman design to identify the main variables affecting the formulation of ADA-MS. The adopted method of preparation for MS was quasi-emulsion solvent diffusion method. The nominated independent variables were volume of organic phase, sonication time, stirring speed, drug percent, polymer type, emulsifier concentration, and method of organic phase addition. As for the dependent variables, they included entrapment efficiency (E.E.%), production yield (P.Y.%), particle size (P.S.) and morphology. Furthermore, selected ADA loaded microsponges (ADA-MS) were in vitro assayed for their biological activities via cytotoxicity, UVA irradiation and cell viability, and antimicrobial activity.

RESULTS

The study indicated that the drug percent, polymer type and surfactant concentration have the key significant effect on E.E.% and P.Y.%, while, the drug percent, stirring speed and volume of organic phase have had a significant effect on P.S. and their morphology. Furthermore, ADA-MS had a momentous cytotoxic effect on A431 and M10 cell-lines with exceptional enrichment when the polymer Eudragit RS100 was used. Also, the ADA-MS increased the cell viability after UVA irradiation on HFB-4 cell-line by 14% to 43%, especially when using Ethyl Cellulose as a polymer. Lastly, the antimicrobial activity of ADA against Propionibacterium acnes was boosted when incorporated into MS.

CONCLUSION

The Plackett-Burman design proved its impact in discerning preparation variables affecting the quality of ADA-MS formulation, with heightening of the in vitro biological activities of ADA. Thus, MS was presumed to be an auspicious carrier system for ADA.

Trifarotene: A Novel Therapeutic Option for Acne

Acne vulgaris, or acne, is a prevailing cutaneous predicament that customarily crops up on the face, neck, and trunk in the forms of comedones, papules, pustules, and nodules. According to epidemiologic explorations, acne affects 9.4% of the global population, making it the eighth most common disease globally. Acne perturbs up to 85% of adolescents, while it is periodically misconceived as an ailment that affects teenagers only; nonetheless, it also affects myriad adults. Acne has well-documented psychosocial ramifications, including adverse effects on self-perception, mental health, and social functioning. Trifarotene is basically a novel fourth-generation locally applied retinoid approved for the first time in the regimens of both face and truncal acnes. The exclusive topical retinoid that adheres precisely to RAR-gamma, the epidermis' most frequent isoform, is trifarotene, approved in October 2019. The current review evaluates the role of trifarotene in treating acne.

Transcriptomics Analysis Indicates Trifarotene Reverses Acne-Related Gene Expression Changes

Background and Objectives: Trifarotene is a topical retinoid selective for retinoic acid receptor gamma that was recently approved for treatment of acne vulgaris. We performed a gene expression analysis to identify the molecular and cellular impact of trifarotene treatment on acne papules. Methods: In this open-label prospective study, subjects with moderate inflammatory acne of the back were treated with trifarotene 0.005% or vehicle cream on dedicated areas for 27 days, and 4 biopsies were collected from each subject (1 from skin without a visible acne lesion and three at the site of an acne papule: one baseline, one after vehicle treatment, and one after trifarotene treatment). Large scale gene expression profiling of the biopsies was performed using Affymetrix technology, treatment-specific gene expression profiles were generated using statistical modeling, and pathway analysis was performed. Using single-cell RNAseq data, in silico deconvolution of transcriptomics data was performed to identify cellular signatures. Results: We discovered a unique set of 67 genes modulated by trifarotene that are primarily involved in cellular migration, inflammation, and extracellular matrix reorganization. Changes in cellular expression were similar in both trifarotene-treated and spontaneously-resolving lesions. However, only trifarotene treatment impacted SPP1⁺ macrophages, a subset of highly proliferative macrophages recently identified in fibrotic tissue. Conclusions: These results show that trifarotene has a novel action in acne treatment by affecting epidermal and immune components of acne pathogenesis.

Selective Activation of MST1/2 Kinases by Retinoid Agonist Adapalene Abrogates AURKA-Regulated Septic Arthritis

Septic arthritis is a chronic inflammatory disorder caused by Staphylococcus aureus invasion of host synovium, which often progresses to impairment of joint functions. Although it is known that disease progression is intricately dependent on dysregulated inflammation of the knee joint, identification of molecular events mediating such imbalance during S. aureus-induced septic arthritis still requires detailed investigation. In this article, we report that Aurora kinase A (AURKA) responsive WNT signaling activates S. aureus infection-triggered septic arthritis, which results in inflammation of the synovium. In this context, treatment with adapalene, a synthetic retinoid derivative, in a mouse model for septic arthritis shows significant reduction of proinflammatory mediators with a simultaneous decrease in bacterial burden and prevents cartilage loss. Mechanistically, adapalene treatment inhibits WNT signaling with concomitant activation of HIPPO signaling, generating alternatively activated macrophages. Collectively, we establish adapalene as a promising strategy to suppress S. aureus-induced irreversible joint damage.

Trifarotene: A Current Review and Perspectives in Dermatology

Retinoids have numerous applications in inflammatory, dyskeratotic, and oncohematology diseases. Retinoids have now reached the fourth generation, progressively reducing toxicity whilst increasing their efficacy. Trifarotene is a new fourth-generation retinoid with a selective action on RAR-γ. In this review, we reported the trials—both concluded and in progress—including the use of trifarotene in dermatological diseases. Studies were identified by searching electronic databases (MEDLINE, EMBASE, PubMed, Cochrane, Trials.gov) from 2012 to today and reference lists of respective articles. Only articles published in English language were included. Randomized trials evaluating trifarotene tolerability, safety, and efficacy in congenital ichthyosis and acne have demonstrated great results and mild side effects, leading to the approval by the FDA of trifarotene for the treatment of lamellar ichthyosis in 2014, and of acne vulgaris in October 2019. No high-quality randomized clinical trials have evaluated the treatment of primary cutaneous lymphomas with trifarotene. Finally, we are hypothesizing future perspectives in the treatment of non-melanoma skin cancers, fungal infections, photoaging, and hand-foot skin reactions with trifarotene.

Increase adapalene delivery using chemical and herbal enhancers

BACKGROUND

Acne is one of the skin diseases that include abnormalities in the production of sebum, changes in the microbial flora, abnormal keratinization, and inflammation. Adapalene is a good choice in the treatment of acne with fewer side effects and high effectiveness. However, the absorption of adapalene through human skin is low. We investigated the effect of several enhancers on the skin absorption of adapalene.

METHODS

For the preparation of a topical formulation, this drug needs proper skin absorption. Therefore, to increase the effect of chemical absorption of the Adapalene skin permeability, it should first be put on the skin in a touch of some absorption like Eucalyptus, Urea, Clove oil, propylene glycol, and oleic acid for 1 and 2 hours and was then examined for the passing of the drug on the treated skin and for the effect of absorptions by calculating of the permeability parameters using DSC and FT-IR techniques.

RESULT AND CONCLUSION

The results show that the enhancers used increased the permeability of the drug adapalene to water. Several mechanisms including lipid liquefaction, degradation of the fat structure, as well as irreversible denaturation of intracellular creatine caused by Eucalyptus, urea clove oil, PG, and oleic acid are the main mechanisms of drug penetration. Based on the results, it was found that among the enhancers studied, eucalyptus and urea had the highest and the lowest absorption effect in 2- and 1-hour pre-contact, respectively.

Role of Vitamins in Skin Health: a Systematic Review

PURPOSE OF REVIEW

Skin is the main defense organ of the human body against external insults (ultraviolet radiations, infections by pathogenic microorganisms, and mechanical and chemical stress). The integrity and functions of the skin barrier are supported by an adequate supply of micronutrients, such as several vitamins. The purpose of this review was to analyze all vitamin-related skin problems.

RECENT FINDINGS

The World Health Organization has estimated that more than 2 billion people worldwide experience deficiencies in the intake of essential vitamins and minerals; the percentage of adults all over the world using daily vitamin supplements, for treatment or prevention of chronic disease, has increased very rapidly in recent years. In this review, 65 studies have been selected in order to examine the role of the main vitamins and their derivatives involved in maintaining the well-being of the skin and their use as prophylactic and therapeutic agents in the management of skin disorders.

Effects of Diet on Acne and Its Response to Treatment

Our understanding of the pathogenesis of acne vulgaris is still evolving. It is known that multiple factors impact acne pathophysiology, including genetic, hormonal, inflammatory, and environmental influences. Because of its implications in many of these factors, diet has been a part of the acne discussion for decades. Several studies have evaluated the significance of the glycemic index of various foods and glycemic load in patients with acne, demonstrating individuals with acne who consume diets with a low glycemic load have reduced acne lesions compared with individuals on high glycemic load diets. Dairy has also been a focus of study regarding dietary influences on acne; whey proteins responsible for the insulinotropic effects of milk may contribute more to acne development than the actual fat or dairy content. Other studies have examined the effects of omega-3 fatty acid and γ-linoleic acid consumption in individuals with acne, showing individuals with acne benefit from diets consisting of fish and healthy oils, thereby increasing omega-3 and omega-6 fatty acid intake. Recent research into the effects of probiotic administration in individuals with acne present promising results; further study of the effects of probiotics on acne is needed to support the findings of these early studies. In this review, we discuss the current evidence regarding the diets of US patients with acne and how they may impact acne and acne treatment.

Recent Advances Regarding the Therapeutic Potential of Adapalene

Adapalene (ADP) is a representative of the third retinoids generation and successfully used in first-line acne treatment. ADP binds to retinoic acid nuclear receptors. The comedolytic, anti-inflammatory, antiproliferative, and immunomodulatory are the known ADP effects. Its safety profile is an advantage over other retinoids. ADP recently was found to be effective in the treatment of several dermatological diseases and photoaging besides the utility in the treatment of acne vulgaris. New biological effects of adapalene with therapeutic potential are highlighted in this review paper. Thus, adapalene could be a valuable therapeutic drug into the treatment of several types of cancer. Additionally, some neurodegenerative diseases could be treated with a suitable formulation for intravenous administration. The antibacterial activity against methicillin-resistant Staphylococcus aureus of an analogue of ADP has been proven. In different therapeutic schemes, ADP is more effective in combination with other active substances. New topical combinations with adapalene include ketoconazole (antifungal), mometasone furoate (anti-inflammatory corticosteroid), nadifloxacin (fluoroquinolone), and alfa and beta hydroxy acids. Combination with oral drugs is a new trend that enhances the properties of topical formulations with adapalene. Several studies have investigated the effects of ADP in co-administration with azithromycin, doxycycline, faropenem, isotretinoin, and valganciclovir. Innovative formulations of ADP also aim to achieve a better bioavailability, increased efficacy, and reduced side effects. In this review, we have highlighted the current studies on adapalene regarding biological effects useful in various treatment types. Adapalene has not been exploited yet to its full biological potential.

A strategic review on the involvement of receptors, transcription factors and hormones in acne pathogenesis

Acne vulgaris is a very common pilosebaceous inflammatory disease occurring primarily on the face and also rare on the upper arms, trunk, and back, which is caused by Propionibacterium, Staphylococcus, Corynebacterium, and other species. Pathophysiology of acne comprises of irregular keratinocyte proliferation, differentiation, increased sebum output, bacterial antigens and cytokines induced inflammatory response. Treatment of acne requires proper knowledge on the pathophysiology then only the clinician can come out with a proper therapeutic dosage regimen. Understanding the pathophysiology not only includes the mechanism but also involvement of receptors. Thus, this review is framed in such a way that the authors have focused on the disease acne vulgaris, pathophysiology, transcription factors viz. the Forkhead Box O1 (FoxO1) Transcription Factor, hormones like androgens and receptors such as Histamine receptors, Retinoic receptor, Fibroblast growth factor receptors, Toll like receptor, Androgen receptor, Liver X-receptor, Melanocortin receptor, Peroxisome proliferator-activated receptor and epidermal growth factor receptors involvement in the progression of acne vulgaris.

A Direct Approach to Decoration of Bioactive Compounds via C-H Amination Reaction

The development of new methods to achieve the direct synthesis of bioactive organic molecules is always an important topic in organic synthesis. We hereby demonstrate that N-methoxyamide is an excellent amino source in the iridium-catalyzed intermolecular C-H amination reaction. The linkage of two bioactive organic molecules can be well achieved with this new protocol. More than 20 examples of decorated bioactive compounds were reported, which can facilitate the discovery of new bioactive molecules.

Photostability of Topical Agents Applied to the Skin: A Review

Topical treatment modalities have multiple advantages starting with the convenient application and non-invasive treatment and ending with the reduction of the risk of the systemic side effects. Active pharmaceutical substances must reach the desired concentration at the target site in order to produce a particular therapeutic effect. In contrast to other dosage forms topical agents applied to the skin may also be susceptible to photodegradation after application. That is why the knowledge of the susceptibility of these topical drugs to UV irradiation, which may contribute to their degradation or changes in chemical structure, is very important. Active pharmaceutical substances used in dermatology may differ both in chemical structure and photostability. Furthermore, various factors-such as light intensity and wavelength, pH, temperature, concentration-can influence the photodegradation process, which is reflected in particular in kinetics of photodegradation of active pharmaceutical substances as well as both the quantitative and qualitative composition of by-products. The aim of this study was to conduct a systematic review of the photostability of dermatological drugs, as well as of other substances commonly applied topically. The photostability of glucocorticosteroids, retinoids, and antifungal drugs as well as non-steroidal anti-inflammatory drugs applied topically and selected UV-filters have been discussed. Furthermore, the impact of photoinstability on the effectiveness of pharmacotherapy and some photostabilization strategies have been also included.

Retinoids as an Immunity-modulator in Dermatology Disorders

The skin is the largest epithelial surface protecting the body from invading microbes. Vitamin A plays vital roles in the host defence of the skin, including promoting epithelial cell integrity, proliferation, and differentiation and even mediating immune responses. Furthermore, vitamin A derivatives, retinoid drugs, are widely used to treat skin diseases, such as acne and psoriasis. However, the immunoregulatory mechanisms of retinoids in dermatology have not been systematically described. In this paper, we discuss the immunological functions of retinoids during disease treatment, especially in skin disorders caused by exogenous infections.

Adapalene Gel 0.1% Versus Placebo as Prophylaxis for Anti-Epidermal Growth Factor Receptor-Induced Acne-Like Rash: A Randomized Left-Right Comparative Evaluation (APPEARANCE)

LESSONS LEARNED

The results of the APPEARANCE trial indicate that adapalene does not prevent acne-like rash over placebo when added to topical moisturizer and oral minocycline but instead may have a detrimental effect. Therefore, adapalene is not recommended as prophylaxis against acne-like rash induced by anti-epidermal growth factor receptor therapies.Given that acne-like rash was completely controlled with placebo in approximately half of patients, predictive measures to identify patients needing intensive prophylaxis are required.

BACKGROUND

Anti-epidermal growth factor receptor (EGFR) therapies are frequently associated with acne-like rash. To evaluate the prophylactic efficacy of adapalene, a topical retinoid used as first-line therapy for acne vulgaris, we conducted a randomized, placebo-controlled, evaluator-blinded, left-right comparative trial.

METHODS

Patients with non-small cell lung, colorectal, or head and neck cancer scheduled to receive anti-EGFR therapies were randomly assigned to once-daily adapalene application on one side of the face, with placebo on the other side. All patients had topical moisturizer coapplied to both sides of the face, and received oral minocycline. The primary endpoint was the difference in total facial lesion count of acne-like rash at 4 weeks. Secondary endpoints included complete control rate (CCR) of acne-like rash (≤5 facial lesions) and global skin assessment (Investigator's Global Assessment [IGA] scale, grade 0-4) at 4 weeks. Two blinded dermatologists independently evaluated the endpoints from photographs.

RESULTS

A total of 36 patients were enrolled, of whom 26 were evaluable. Adapalene treatment was associated with a greater lesion count than placebo at 4 weeks, although the difference was not statistically significant (mean, 12.6 vs. 9.8, p = .12). All four patients with a difference >10 in lesion count between face sides had a greater count on the adapalene-treated side. No significant differences were observed in CCR of acne-like rash (54% vs. 50%) or IGA scale (mean grade, 1.9 vs. 1.7) between the adapalene and placebo sides.

CONCLUSION

Adapalene is not recommended as prophylaxis against acne-like rash induced by anti-EGFR therapies.

From pathogenesis of acne vulgaris to anti-acne agents

Acne vulgaris is a cutaneous chronic inflammatory disorder with complex pathogenesis. Four factors play vital roles in acne pathophysiology: hyperseborrhea and dysseborrhea, altered keratinization of the pilosebaceous duct, Cutibacterium acnes (C. acnes) and inflammation. The main hormones responsible for the development of acne vulgaris include androgens, insulin and insulin-like growth factor-1. Other factors involved in this process are corticotropin-releasing hormone, α-melanocyte-stimulating hormone and substance P. Wnt/β-catenin signaling pathway, phosphoinositide 3-kinase (PI3K)/Akt pathway, mitogen-activated protein kinase pathway, adenosine 5'-monophosphate-activated protein kinase pathway and nuclear factor kappa B pathway participate in the modulation of sebocyte, keratinocyte and inflammatory cell (e.g. lymphocytes, monocytes, macrophages, neutrophils) activity. Among all the triggers and pathways mentioned above, IGF-1-induced PI3K/Akt/Forkhead box protein O1/mammalian target of rapamycin (mTOR) C1 pathway is the most important signaling responsible for acne pathogenesis. Commonly used anti-acne agents include retinoids, benzoyl peroxide, antibiotics and hormonal agents (e.g. spironolactone, combination oral contraceptive and flutamide). New approaches including peroxisome proliferator-activated receptor γ modifier, melanocortin receptor antagonists, epigallocatechin-3-gallate, metformin, olumacostat glasaretil, stearoyl-CoA desaturase inhibitor omiganan pentahydrochloride, K_DPT, afamelanotide, apremilast and biologics have been developed as promising treatments for acne vulgaris. Although these anti-acne agents have various pharmacological effects against the diverse pathogenesis of acne, all of them have a synergistic mode of action, the attenuation of Akt/mTORC1 signaling and enhancement of p53 signal transduction. In addition to drug therapy, diet with no hyperglycemic carbohydrates, no milk and dairy products is also beneficial for treatment of acne.

Why Topical Retinoids Are Mainstay of Therapy for Acne

Acne-focused dermatology expert groups have consistently recommended that most patients with acne be treated with a combination of topical retinoid and antimicrobial therapy. This is based on clinical data as well as evidence that these drug classes have different and complementary mechanisms of action that target multiple aspects of acne's complex pathophysiology. Recent evidence-based guidelines for acne, including those from the American Academy of Dermatology (AAD) and the European Dermatology Forum (EDF), have agreed that retinoids have an essential role in this widespread disease. The AAD states "retinoids are the core of topical therapy for acne because they are comedolytic, resolve the precursor microcomedone lesion, and are anti-inflammatory;" further, they "allow for maintenance of clearance." Despite uniform recommendation for use of topical retinoids, a recent study of prescribing practices from 2012 to 2014 indicated that dermatologists prescribed retinoids just 58.8% of the time while non-dermatologists prescribed them for only 32.4% of cases. In this article, we review the reasons supporting retinoids as the mainstay of acne therapy and discuss some of the perceived barriers that may be limiting use of this important drug class. Further, we discuss how and when titrating retinoid concentrations may be utilized in clinical practice.

FUNDING

Galderma International.

New developments in acne treatment: role of combination adapalene-benzoylperoxide

The fixed-dose combination adapalene 0.1%/benzoylperoxide 2.5% (A/BPO) was introduced as an acne vulgaris therapeutic in 2007. It combines anti-inflammatory, keratolytic, comedolytic, and antibacterial properties. Thus, it addresses several pathophysiological factors involved in the pathophysiology of acne. This review highlights the rationale for the use of this fixed-dose combination product, its therapeutic efficacy including effects on adherence and quality of life, its use for different forms of acne, and the side-effect profile. In summary, the fixed-dose combination of A/BPO gel can be regarded as a highly effective and safe formulation. It is not associated with antibiotic resistance. It reduces factors that cause nonadherence and has positive effects on the quality of life of affected patients. The tolerance is good. The initial mild irritation potential can be addressed by adequate counseling. A/BPO can be used for all forms of inflammatory acne, including severe forms, as part of a combination with systemic antibiotics. Finally, it can also be used for the long-term treatment of chronic acne. Thus, it is a very valuable therapeutic option in daily practice, which is reflected by its strong recommendation in the “European S3-guidelines”.

Applications and limitations of lipid nanoparticles in dermal and transdermal drug delivery via the follicular route

Lipid nanoparticles (LN) such as solid lipid nanoparticles (SLN) and nanolipid carriers (NLC) feature several claimed benefits for topical drug therapy including biocompatible ingredients, drug release modification, adhesion to the skin, and film formation with subsequent hydration of the superficial skin layers. However, penetration and permeation into and across deeper skin layers are restricted due to the barrier function of the stratum corneum (SC). As different kinds of nanoparticles provide the potential for penetration into hair follicles (HF) LN are applicable drug delivery systems (DDS) for this route in order to enhance the dermal and transdermal bioavailability of active pharmaceutical ingredients (API). Therefore, this review addresses the HF as application site, published formulations of LN which showed follicular penetration (FP), and characterization methods in order to identify and quantify the accumulation of API delivered by the LN in the HF. Since LN are based on lipids that appear in human sebum which is the predominant medium in HF an increased localization of the colloidal carriers as well as a promoted drug release may be assumed. Therefore, sebum-like lipid material and a size of less or equal 640 nm are appropriate specifications for FP of particulate formulations.

Efficacy of 0.1% adapalene in a non-inflammatory Kyoto Rhino Rat acne model

BACKGROUND

Acne vulgaris is a disorder of the pilosebaceous unit of the skin, and the underlying mechanism is still obscure. Kyoto rhino (krh/krh) rats were made by ethylnitrosourea (ENU) mutagenesis and harbor S413X nonsense mutation of the rat hairless (Hr) gene. Krh/krh rats develop comedones with hair loss on their back as they grow.

OBJECTIVE

Our purpose is to assess whether or not the krh/krh rat is a suitable model of non-inflammatory acne, and to investigate the comedolytic effects of adapalene in krh/krh rats.

METHODS

Krh/krh rats at 12weeks of age were topically treated with adapalene or a vehicle 6 times a week, for 12weeks. Skin lesions were clinically investigated and skin samples were obtained from treated skins from each animal after 6 and 12weeks of treatments.

RESULTS

Comedone was clinically enlarged in the control group compared with the adapalene group. The adapalene group showed significantly increased epidermal thickness as compared to the control group. Furthermore, open comedone areas were also significantly decreased in the adapalene group as compared to the control group. The adapalene group also showed reduced lipid production in open comedones as compared to the control group. Cytokine productions including IL-10 and IL-12a tended to increase in skin treated with adapalene as compared to the control group.

CONCLUSION

Krh/krh rats represented a new model for non-inflammatory acne with abnormalities in both hair follicles and sebaceous glands. It is hypothesized that adapalene is a superior drug to decrease open comedones by modifying lipid metaboism and cytokine production in krh/krh rats.

Adapalene 0.1%/benzoyl peroxide 2.5% gel: a review of its use in the treatment of acne vulgaris in patients aged ≥ 12 years

Adapalene 0.1%/benzoyl peroxide 2.5% gel (Epiduo™, Tactuo™) is the only fixed-dose combination product available that combines a topical retinoid with benzoyl peroxide; it targets three of the four main pathophysiologic factors in acne. This article reviews the therapeutic efficacy and tolerability of topical adapalene 0.1%/benzoyl peroxide 2.5% gel in the treatment of patients aged ≥ 12 years with acne vulgaris, as well as summarizing its pharmacologic properties. In three 12-week trials in patients aged ≥ 12 years with moderate acne, success rates were significantly higher with adapalene 0.1%/benzoyl peroxide 2.5% gel than with adapalene 0.1% gel or benzoyl peroxide 2.5% gel alone, and combination therapy had an earlier onset of action. In addition, significantly greater reductions in total, inflammatory, and noninflammatory lesion counts were seen in patients receiving adapalene 0.1%/benzoyl peroxide 2.5% gel than in those receiving adapalene 0.1% gel or benzoyl peroxide 2.5% gel alone. Adapalene 0.1%/benzoyl peroxide 2.5% gel did not significantly differ from clindamycin 1%/benzoyl peroxide 5% gel in terms of the reduction in the inflammatory, noninflammatory, or total lesion counts in patients with mild to moderate acne, according to the results of a 12-week trial. Twelve-week studies showed that topical adapalene 0.1%/benzoyl peroxide 2.5% gel in combination with oral lymecycline was more effective than oral lymecycline alone in patients with moderate to severe acne, and topical adapalene 0.1%/benzoyl peroxide 2.5% gel in combination with oral doxycycline hyclate was more effective than oral doxycycline hyclate alone in patients with severe acne. In patients with severe acne who responded to 12 weeks' therapy with topical adapalene 0.1%/benzoyl peroxide 2.5% gel plus oral doxycycline hyclate or oral doxycycline hyclate alone, an additional 6 months' therapy with adapalene 0.1%/benzoyl peroxide 2.5% gel was more effective than vehicle gel at maintaining response, with further improvement seen in adapalene 0.1%/benzoyl peroxide 2.5% gel recipients. A noncomparative study also demonstrated the efficacy of 12 months' therapy with adapalene 0.1%/benzoyl peroxide 2.5% gel in patients with acne vulgaris. Topical adapalene 0.1%/benzoyl peroxide 2.5% gel was generally well tolerated in patients with acne. In 12-week trials, the most commonly occurring treatment-related adverse events included erythema, scaling, dryness, and stinging/burning; these dermatologic treatment-related adverse events were usually of mild to moderate severity, occurred early in the course of treatment, and resolved without residual effects. Topical adapalene 0.1%/benzoyl peroxide 2.5% gel was generally well tolerated in the longer term, with dry skin being the most commonly occurring treatment-related adverse event over 12 months of treatment. In conclusion, adapalene 0.1%/benzoyl peroxide 2.5% gel is a valuable agent for the first-line treatment of acne vulgaris.

New insights into the management of acne: an update from the Global Alliance to Improve Outcomes in Acne group

The Global Alliance to Improve Outcomes in Acne published recommendations for the management of acne as a supplement to the Journal of the American Academy of Dermatology in 2003. The recommendations incorporated evidence-based strategies when possible and the collective clinical experience of the group when evidence was lacking. This update reviews new information about acne pathophysiology and treatment-such as lasers and light therapy-and relevant topics where published data were sparse in 2003 but are now available including combination therapy, revision of acne scarring, and maintenance therapy. The update also includes a new way of looking at acne as a chronic disease, a discussion of the changing role of antibiotics in acne management as a result of concerns about microbial resistance, and factors that affect adherence to acne treatments. Summary statements and recommendations are provided throughout the update along with an indication of the level of evidence that currently supports each finding. As in the original supplement, the authors have based recommendations on published evidence as much as possible.

A review of adapalene in the treatment of acne vulgaris

Topical retinoids help address the early lesions of acne vulgaris. Consensus guidelines advocate the use of topical retinoids as the primary treatment for most forms of acne vulgaris. However, all topical retinoid preparations may be irritating, and this may contribute to underutilization in clinical practices. Topical adapalene fosters topical retinoid treatment of acne with less irritation. Adapalene is a more stable molecule than tretinoin. Adapalene can be used without concern for photo-deactivation. Because of its chemical stability, adapalene can be used in combination with benzoyl peroxide products. The availability of a stable topical retinoid associated with little irritation may facilitate meeting acne treatment consensus guidelines.

In vitro modulation of TLR-2, CD1d and IL-10 by adapalene on normal human skin and acne inflammatory lesions

The anti-inflammatory mechanisms of adapalene, a synthetic retinoid used for the treatment of acne patients, are partially understood. They seem particularly related to the modulation of the non-specific immunity. Recent studies have shown that Toll-like receptor (TLR)-2 expression, a receptor of the innate immune system, was increased in acne lesions and could play an essential role in acne-linked inflammation. The aim of our study was to investigate the new mechanisms of the anti-inflammatory activity of adapalene in vitro, and more specifically the modulatory effect of adapalene on the expression of TLR-2, CD1d, a cell surface glycoprotein that plays a role as antigen-presenting molecules and is responsible for the development of cutaneous inflammation, and also on the expression and the secretion of the anti-inflammatory interleukin (IL)-10 cytokine. Both explants of normal human skin and explants of acne patients were incubated with adapalene (10(-7) or 10(-6) M) or the control medium for 24 h. Evaluation of epidermal expression by immunohistochemistry showed a decreased expression of TLR-2 and IL-10 in explants of normal skin and explants of acne with adapalene. On the contrary, adapalene increased CD1d expression in explants of acne patients. Thus, adapalene can modulate the epidermal immune system by increasing the CD1d expression and by decreasing the IL-10 expression by keratinocytes. Moreover, these modulations could increase the interactions between dendritic cells and T lymphocytes and could strengthen the antimicrobial activity against Propionibacterium acnes. The decreased expression of TLR-2 by the keratinocytes can contribute to explain the anti-inflammatory activity of adapalene observed in clinical practice.

Drugs, their targets and the nature and number of drug targets

What is a drug target? And how many such targets are there? Here, we consider the nature of drug targets, and by classifying known drug substances on the basis of the discussed principles we provide an estimation of the total number of current drug targets.

Comparison of short- and long-term cyclosporine A therapy in chronic idiopathic urticaria

BACKGROUND

Chronic idiopathic urticaria is sometimes difficult to treat, with little response to antihistamine therapy.

OBJECTIVE

In a limited number of severe chronic idiopathic urticaria patients, cyclosporine A (CsA) therapy was found to be effective. In this study, we compared the clinical efficacy and safety of short- and long-term CsA applications.

METHODS

Twenty patients with severe disease, unresponsive to antihistamines and showing a positive autologous serum skin test (ASST) were randomized to 4 mg/kg per day of CsA for 4 or 12 weeks. The clinical efficacy was measured with a daily activity score of weal numbers and itch (UAS). The two groups were compared in terms of mean reduction in UAS and ASST response to pre-and post-treatment sera.

RESULTS

The clinical improvement was dramatic in the first month of treatment in both groups. There was no significant difference in the frequency of responses, side effects and the reduction of UAS in either group.

CONCLUSION

The preliminary results of our study suggest that CsA is clinically effective for chronic urticaria. The prolonged use of this therapy for more than 1 month provides little benefit in the clinical improvement.

Retinoids: fascinating up-and-coming scenario

Retinoids have been in sharp focus ever since their introduction 30 years ago. They include any drug (s) that bind to retinoid receptors and elicit a biological response. Enormous information on the subject seems to embroil the recent literature. Practically it is impossible to clearly comprehend the undercurrents. The meticulously dispensing text envisages surmounting the perspective reader's predicaments. Accordingly, retinoids and their related facets namely retinoid receptors, classification, mode of action, and the pharmacological diversity have been precisely defined. Commonly used systemic retinoids too have been given a substantial fresh look along with their monitoring. Overall, adverse effects and relative and absolute contraindications have been scrupulously incorporated. Human immuno deficiency virus (HIV) and isoretinoid for acne, in particular, have been highlighted. Micronized isotretinoin formulations have also been taken care so also commonly used topical retinoids. Tretinoin and their newer formulation have also been accounted for along with tretinoin polymer cream. Adapalene, a new chemical entity possessing a unique physico-chemical activity similar to that of tretinoin has also been dealt with. Newer retinoids are likely to be a subject of intrigue. A focus on future potentials of retinoids is its special ingredient. The inclusion of details of rexinoid the most recent introduction in their purview is likely to invoke interest to further consolidate its reckoning in future. All in all the text of the paper should provide an insight into the current rumbling around retinoids.

Potential anti-inflammatory effects of topical retinoids and retinoid analogues

The topical retinoid tretinoin and topical retinoid analogues such as adapalene and tazarotene help normalize hyperkeratinization in acne vulgaris and have demonstrated significant anti-inflammatory effects in experimental trials. Inhibition of various immune factors, including the activity of leukocytes, the release of proinflammatory cytokines and other mediators, and the expression of transcription factors and toll receptors involved in immunomodulation, has emerged in both in vitro studies and in vivo animal experiments. These multiple mechanisms of action should encourage clinicians to consider these agents in the first-line management of inflammatory acne lesions.