Topically Applied therapies for the treatment of skin disease : Past Present and Future.

The purpose of this review is to summarize essential biological, pharmaceutical and clinical aspects in the field of topically applied medicines that may help scientists when trying to develop new topical medicines. After a brief history of topical drug delivery, a review of the structure and function of the skin, routes of drug absorption and their limitations is then provided. The most prevalent diseases and current topical treatment approaches are then detailed, the organization of which reflects the key disease categories of autoimmune and inflammatory, microbial infections, skin cancers and genetic skin diseases. The complexity of topical product development through to large scale manufacture along with recommended risk mitigation approaches is then highlighted. As such topical treatments are applied externally patient preferences along with the challenges they invoke are then described and finally the future of this field of drug delivery is discussed with the emphasis on areas that are more likely to yield significant improvements over the topical medicines in current use or would expand the range of medicines and diseases treatable by this route of administration. Significance Statement This review of the key aspects the skin, its associated diseases and current treatments along with the intricacies of topical formulation development should be helpful in making judicious decisions about the development of new or improved topical medicines. These aspects include the choices of the active ingredients, formulations, the target patient populations preferences and limitations and the future with regards to new skin diseases and topical medicine approaches.

In vitro studies into establishing therapeutic bioequivalence of complex topical products: Weight of evidence.

Over the past decade, topically applied drug products have experienced extraordinary price increases, due to the shortage of multisource generic drug products. This occurrence is mainly related to the underlying challenges evolved in topical bioequivalence documentation. Although there has been continuing regulatory efforts to present surrogate in vitro methods to clinical endpoint studies, there is still a continued need for cost- and time-efficient alternatives that account for product specificities. Hence, this work intended to expose bioequivalence assessment issues for complex topical formulations, and more specifically those related with product efficacy guidance. As a model drug and product, a bifonazole 10 mg/g cream formulation was selected and two different batches of the commercially available Reference Product (RP) were used: RP1 that displayed lower viscosity and RP4 which presented high, but not the highest, viscosity. In vitro human skin permeation testing (IVPT) was carried out and the results were evaluated by means of the traditional bioequivalence assessment approach proposed by the EMA, as well as by the Scaled Average Bioequivalence assessment approach proposed by the FDA. Based on previous experience, there was an expectation of a high level of variability in the results, thus alternative methods to evaluate local drug skin availability were developed. More specifically, an infected skin disease model, where ex vivo human skin was infected and ATP levels were used as a biological marker for monitoring antifungal activity after product application. The results showed that permeation equivalence could not be supported between the different RP batches. In contrast, this statistical difference between the formulation batches was not indicated in the disease model. Nevertheless, in pivotal IVPT studies, the lowest permeant formulation (RP4) evidenced a higher antifungal in vitro activity as reported by the lower levels of ATP. A critical appraisal of the results is likewise presented, focusing on an outlook of the real applicability of the regulatory guidances on this subject.

A Comprehensive Assessment of Radial Scars on Core Needle Biopsy in Patients with or without Breast Cancer: Upgrade Rate and Implications on Management.

BACKGROUND: Radial scars/radial sclerosing lesions (RS) are benign breast lesions identified on core needle biopsy (CNB) which can upgrade to malignancy at excision. There is limited data on RS detection and upgrade rates with more sensitive imaging such as magnetic resonance imaging (MRI) and none during their detection for breast cancer workup and its implication on patient treatment decisions. METHODS: A retrospective institutional study of RS diagnosed on CNB between January 2008 and December 2017 was conducted. Clinicopathologic and radiologic features of RS, patient treatment decisions, upgrade rates and long-term follow-up were examined. RESULTS: We identified 133 patients with RS on CNB, of whom 106 opted for surgery for an upgrade rate to malignancy of 1.9%, 2 patients. Radial scar was diagnosed on mammogram in 60%, MRI in 25% and ultrasound in 15% of patients. In this cohort, 32 patients had their RS detected during breast cancer workup (coexistent group) and they were more likely to have their radial scar detected by MRI (60% vs. 14%, P < .001) and undergo more extensive surgery (94% vs. 75%, P = .02). Among the 27 patients electing observation of their RS, only one (3.7%) developed breast cancer. CONCLUSIONS: Our results show an extremely low upgrade rate to malignancy of RS, regardless if there is coexisting breast cancer elsewhere. Despite this, RS still prompted more extensive surgical excisions. The findings do not support excision of RS even among breast cancer patients when identified at a separate site from their cancer.

The Plant Defensin Ppdef1 Is a Novel Topical Treatment for Onychomycosis.

Onychomycosis, or fungal nail infection, causes not only pain and discomfort but can also have psychological and social consequences for the patient. Treatment of onychomycosis is complicated by the location of the infection under the nail plate, meaning that antifungal molecules must either penetrate the nail or be applied systemically. Currently, available treatments are limited by their poor nail penetration for topical products or their potential toxicity for systemic products. Plant defensins with potent antifungal activity have the potential to be safe and effective treatments for fungal infections in humans. The cystine-stabilized structure of plant defensins makes them stable to the extremes of pH and temperature as well as digestion by proteases. Here, we describe a novel plant defensin, Ppdef1, as a peptide for the treatment of fungal nail infections. Ppdef1 has potent, fungicidal activity against a range of human fungal pathogens, including Candida spp., Cryptococcus spp., dermatophytes, and non-dermatophytic moulds. In particular, Ppdef1 has excellent activity against dermatophytes that infect skin and nails, including the major etiological agent of onychomycosis Trichophyton rubrum. Ppdef1 also penetrates human nails rapidly and efficiently, making it an excellent candidate for a novel topical treatment of onychomycosis.

Skin permeation and penetration of mometasone furoate in the presence of emollients: An ex vivo evaluation of clinical application protocols.

Background: Topical corticosteroids (TCS) and emollients are developed independently by the pharmaceutical industry but are often used together in practice. There is potential for the TCS and emollient formulations to interact on the skin surface affecting TCS absorption into the skin. Clinical guidelines acknowledge this issue but lack an evidence base and differ in their recommendations. There is a current clinical need to establish whether the application protocol employed for TCS and emollient products can impact delivery of TCS to the skin. Objectives: To investigate whether the sequence of application of a TCS and emollient and the time between their application can affect TCS skin absorption. Methods: The delivery of mometasone furoate (MF) to ex vivo human skin was evaluated following the application of Elocon cream either 5 or 30 min, before and after three different emollients. Mechanistic explanation of the changes in drug absorption was provided by modelling the skin permeation data and Raman microscopy of mixed Elocon cream and emollient formulations. Results: A circa fivefold difference in MF absorption was observed depending on the emollient and application protocol. Applying Elocon cream at short intervals in relation to Hydromol intensive significantly increased MF absorption regardless of the application protocol. In contrast, applying Elocon cream after Diprobase cream or ointment significantly reduced MF absorption relative to Elocon cream alone or when Elocon cream was applied before these emollients. The changes in drug absorption observed were attributed to the presence of emollients altering Elocon cream formulation performance through different mechanisms, including introduction of penetration enhancing excipients and inducing drug crystallization in the mixed TCS emollient layer on the skin surface. Conclusions: Emollients can affect MF absorption in different ways depending on the emollient and sequence of administration. Using a 30 min gap between product applications may not be sufficient to mitigate emollient effects on TCS absorption.

Drilling down the bioequivalence assessment of topical antifungal products: Microstructure and release.

In recent years, the regulatory mechanisms for topical generic product bioequivalence (BE) assessment have been subjected to noteworthy changes, with the FDA issuing product specific guidances, and the EMA adopting a more universal approach with the quality and equivalence of topical products draft guideline. The agencies advise on a modular strategy for BE documentation. Nevertheless, their scope, data analysis and criteria are rather distinct. This study aims to tackle bioequivalence assessment issues of complex topical formulations starting by statistical implications of the EMA/FDA approaches concerning the documentation of qualitative (Q1), quantitative (Q2), microstructure (Q3) and performance requirements (Q4). As a model drug product, a bifonazole 10 mg/g cream formulation was selected. For this specific formulation, the commercially available Reference Product (RP) was compared with two comparator products, also commercially available, referred to as comparator product A (CPA) and comparator product B (CPB). The former displays Q1 sameness and Q2 differences, whilst CPB is categorically considered as Q1/Q2 different. Furthermore, intending to establish a regulatory rationale for the submission of a generic product according to the updated regulatory requirements, the RP was likewise compared with a Test Product (TP). This formulation was designed to display equal Q1/Q2 profile to that of the RP. Validated rheology and in vitro release test (IVRT) methods were used to infer on Q3/Q4 characteristics. During rheology studies, statistically significant RP batch to batch differences were observed. Therefore, in an attempt to surpass this heterogeneity, the initial pool of RP batches was expanded to include RP product batches at different lifecycle stages. Despite this effort, it was not possible to classify the RP/TP, RP/CPA or RP/CPB as rheologically equivalent products. Nevertheless, product performance results, retrieved from IVRT, were able to sustain equivalence between the RP and the formulations exhibiting Q1 sameness (TP and CPA). It should however be mentioned, that for some RP batch combinations, the IVRT results failed to demonstrate equivalence according to the EMA requirements. Enlarging the RP batch pool was then a critical step in further understanding an optimum statistical approach for establishing equivalence in product performance. This study highlights the need to that a 'one-fits-all approach' may not be an optimum path way for establishing the regulatory strategy and requirements to support generic product bioequivalence.

Practice Patterns for Mohs Surgeons of Varying Clinical Experience: A Cross-Sectional Analysis of a Medicare Claims Database.

BACKGROUND: Use of Mohs micrographic surgery (MMS) is highly prevalent, but little data are available on how surgeon experience affects surgical practice patterns. OBJECTIVE: To determine differences in use of MMS among surgeons of varying experience. MATERIALS AND METHODS: This cross-sectional study sampled from clinicians billing ≥200 mean annual Mohs surgery claims from the 2012 to 2018 Medicare Public Use File. The primary outcome was mean annual Mohs surgery claims for clinicians of varying experience. Secondary outcomes included use of flaps/grafts and prescribing of oral antibiotics, benzodiazepines, and opioids. RESULTS: Among 1,759 unique surgeons, those with 16 to 20 years of experience performed the most mean annual (95% confidence interval) Mohs surgical cases (578.7 [556.7-600.6]). Surgeons with 21 to 25 years of experience prescribed the most antibiotics (240.2 [216.5-263.8] mean annual claims), whereas those with >35 years of experience prescribed the longest courses (15.3 [14.2-16.4] days). CONCLUSION: Midcareer surgeons performed the most mean annual Mohs surgery cases, whereas later career surgeons prescribed more frequent and longer courses of antibiotics suggesting changing practice patterns with additional years of experience.

Development of a core outcome set for basal cell carcinoma.

BACKGROUND: There is variation in the outcomes reported in clinical studies of basal cell carcinoma. This can prevent effective meta-analyses from answering important clinical questions. OBJECTIVE: To identify a recommended minimum set of core outcomes for basal cell carcinoma clinical trials. METHODS: Patient and professional Delphi process to cull a long list, culminating in a consensus meeting. To be provisionally accepted, outcomes needed to be deemed important (score, 7-9, with 9 being the maximum) by 70% of each stakeholder group. RESULTS: Two hundred thirty-five candidate outcomes identified via a systematic literature review and survey of key stakeholders were reduced to 74 that were rated by 100 health care professionals and patients in 2 Delphi rounds. Twenty-seven outcomes were provisionally accepted. The final core set of 5 agreed-upon outcomes after the consensus meeting included complete response; persistent or serious adverse events; recurrence-free survival; quality of life; and patient satisfaction, including cosmetic outcome. LIMITATIONS: English-speaking patients and professionals rated outcomes extracted from English language studies. CONCLUSION: A core outcome set for basal cell carcinoma has been developed. The use of relevant measures may improve the utility of clinical research and the quality of therapeutic guidance available to clinicians.

Accelerating topical formulation development for inflammatory dermatoses; an ex vivo human skin culture model consistent with clinical therapeutics.

Although animal models have been extensively used to evaluate human topical therapeutics, they exhibit marked physiological differences to human skin. Our objective was to develop a human ex vivo skin culture model to explore the pathophysiology of inflammatory dermatoses and for preclinical testing of potential therapeutic treatments. Ex vivo skin barrier integrity and metabolic activity was retained for 5 days and stimulation of T-helper cells (Th1), which produce proinflammatory cytokines, provided inflammatory responses similar to those reported from in vivo biopsy. Tissue responses to established therapies of pimecrolimus (Elidel) and clobetasol propionate (Dermovate) were evaluated using the human ex vivo skin culture, assessing pharmacodynamic changes in gene expression alongside the pharmacokinetics of drug penetration with both products showing time dependent efficacies. The translational utility of the human ex vivo skin culture model of inflammatory dermatoses was demonstrated through comparison with an in vivo clinical study, with similar reductions in inflammatory gene expression recorded for both drug treatments. Thus, this model can reduce, replace or refine animal testing and also mitigate the risk of failure in costly and time-consuming clinical trials associated with novel topical therapeutic development.

Topical bioequivalence: Experimental and regulatory considerations following formulation complexity.

Documenting topical bioequivalence can be an extremely complex process, which is intrinsically dependent on the formulation technological features. According to EMA guideline, for simple formulations, BE may be demonstrated by documenting the qualitative (Q1), quantitative (Q2), microstructure (Q3) and performance (Q4) equivalence. Nevertheless, when addressing complex semisolids, equivalence regarding local availability should also be demonstrated. The purpose of this study is to pursue this strategy using two opposite scenarios: a simple dimetindene maleate 1 mg/g gel formulation and a diclofenac diethylammonium 23.2 mg/g emulgel, representing a complex formulation. For both formulations, Q1/Q2 test (TP) and reference products (RP) were used. Rheology, in vitro release (IVRT) and in vitro permeation methods (IVPT) were developed and validated for both products. For the dimetindene formulation, equivalence pertaining to Q4 was established. However, high variability was observed for some rheology endpoints, especially for the different RP batches. Therefore, equivalence could not be established for Q3 as per EMA requirements. Can some rheology endpoints be waived? Can we establish reasonable criteria that are overall feasible for generic manufacturers and at the same time safe for the patient? An attempt was made to propose a wider acceptance range based on the inter-batch variability of the RP. For that, the rationale presented in the EMA guideline on bioequivalence for highly variable products was used. For the diclofenac formulation, Q3 equivalence was likewise not established. Q4 equivalence was only found for some batch combinations and when applying a wider acceptance criterion (75-133%). Furthermore, IVPT equivalence also failed to be demonstrated. Nevertheless, since the TP displays an equivalent pharmacokinetic profile compared to the RP, the observed Q3, Q4 and local availability differences are not expected to be clinically significant. This study draws attention to an effective search to determine the most appropriate strategy for assessing topical bioequivalence on a case-by-case basis.

A new ex vivo skin model for mechanistic understanding of putative anti-inflammatory topical therapeutics.

Several in vitro models have been designed as test systems for inflammatory skin conditions, commonly using cell-culture or reconstructed human epidermis approaches. However, these systems poorly recapitulate the physiology and, importantly, the metabolism and biochemical activity of skin in vivo, whereas ex vivo skin culture models can retain these features of the tissue. Our objective was to develop a human ex vivo skin culture model to explore the pathophysiology of inflammatory dermatoses and for preclinical testing of potential therapeutic treatments. Following exogenous stimulation, tissue integrity and ability to induce inflammatory gene expression was retained, and stimulant concentrations and duration was optimised to mimic published data from inflammatory clinical biopsies of dermatitis and psoriasis patients. The validity and utility of the model was demonstrated when challenged with 5 drugs including a corticosteroid and vitamin D3 analogue, where inflammatory biomarkers were regulated in a manner consistent with the drugs' reported in vivo mechanisms of action. This model retains important inflammatory gene signals observed in human inflammatory dermatoses for preclinical evaluation of novel therapeutics.

Athletic Injuries of the Thoracic Cage.

A variety of sports require exposure to high-impact trauma or characteristic repetitive movements that predispose to injuries around the thorax. Appropriate prognostication and timely management are vital, as untreated or undertreated injuries can lead to pain, disability, loss of playing time, or early termination of sports participation. The authors review common athletic injuries of the thoracic cage, encompassing muscular, osseous, and vascular conditions, with an emphasis on mechanism, imaging features, and management. The authors also review pertinent soft-tissue and bony anatomy, along with relevant sports biomechanics. Generalized muscle trauma and more specific injuries involving the pectoralis major, latissimus dorsi, teres major, pectoralis minor, lateral abdominal wall and intercostals, serratus anterior, and rectus abdominis muscles are discussed. Osseous injuries such as stress fractures, sternoclavicular dislocation, costochondral fractures, and scapular fractures are included. Finally, thoracic conditions such as snapping scapula, thoracic outlet syndrome, and Paget-Schroetter syndrome are also described. Specific MRI protocols are highlighted to address imaging challenges such as the variable anatomic orientation of thoracic structures and artifact from breathing motion. Athletes are susceptible to a wide range of musculoskeletal thoracic trauma. An accurate imaging diagnosis of thoracic cage injury and assessment of injury severity allow development of an adequate treatment plan. This can be facilitated by an understanding of functional anatomy, sports biomechanics, and the unique injuries for which athletes are at risk. ©RSNA, 2021.

Penetration of Flurbiprofen from a Locally Applied Sore Throat Lozenge and Spray into Cadaveric Human Pharynx Tissue: A Novel ex vivo Model and Microautoradiography Method.

OBJECTIVE: Flurbiprofen 8.75 mg lozenge and spray are used for symptomatic relief of sore throat, with a rapid onset of analgesia suggesting a localized mechanism of action. Building on previous studies, this investigation aimed to use microautoradiography to visualize the depth penetration of radiolabeled flurbiprofen into human pharynx tissue using an ex vivo model. Quantification of flurbiprofen in the tissue was performed to provide a quantitative representation of flurbiprofen distribution through the tissue. METHODS: Cadaveric human pharynx tissue was mounted between the donor and receiver compartments of a Franz diffusion cell. After that 8.75 mg spray and dissolved lozenge formulations, containing radiolabeled flurbiprofen, were added to the donor compartment of a Franz diffusion cell. After incubation for one hour, the pharynx tissue was removed, processed, and sectioned both horizontally and vertically. The sections were placed within an imaging cassette to determine the penetration of radiolabeled flurbiprofen visually, before being solubilized to quantify the amount of flurbiprofen present in each section. RESULTS: In the horizontally sectioned samples, flurbiprofen was present in the top layers of all replicates and decreased in intensity throughout the tissue. Of the applied dose, 48.0-99.9% of flurbiprofen was detected in the top one-third of the pharynx tissue, closest to the dosing site, and 0-14.8% of flurbiprofen was detected within the deepest third of pharynx tissue, furthest from the dosing site. In the vertically sectioned tissue samples, radiolabeled flurbiprofen was found at a high intensity at the dosing site and reduced in intensity throughout the thickness of the tissue. Lateral penetration of flurbiprofen was also seen in tissue dosed with the spray. CONCLUSION: Our findings demonstrate that lozenge and spray formulations of flurbiprofen can penetrate throughout the layers of cadaveric human pharynx tissue in an ex vivo model, as visualized by microautoradiography.

Indications and Outcomes of Mohs Micrographic Surgery Using a Multidisciplinary Approach: A Decade of Experience.

BACKGROUND: Traditional approaches of staged outpatient Mohs Micrographic Surgery (MMS) in nonmelanoma skin cancer (NMSC) followed by reconstruction is not possible in a subset of patients. OBJECTIVE: Assess the indications and outcomes of a multidisciplinary approach MMS. METHODS AND MATERIALS: Retrospective, single-surgeon, single Mohs specialist, university-based tertiary care referral practice, including all MMS performed in the operating room setting with concurrent reconstruction in patients from 2008 to 2018 with minimum follow-up of 6 months. Patients with NMSCs who completed multidisciplinary MMS approach were included. Number of Mohs stages, duration of procedure, reconstruction techniques, and complications including flap loss, bleeding, hematoma, wound infections, dehiscence, and local recurrence rates were reviewed. RESULTS: Three hundred twenty patients were included, 160 male and 160 female with mean ages of 71.6 and 72.1 years, respectively. Indications for a multidisciplinary approach MMS were as follows: neuro/psych 22.5%, extensive anticipated defect size 55%, patient request/convenience 4.4%, medical intolerance 5%, multiple reasons 8.1%, and unknown in 5%. Average stage required to clear margins was 1.57 ± 0.64. Mean operative times by increasing Mohs stages up to 3 including reconstruction were 125.1, 159.3, and 195.5 minutes, respectively (p < .00001). CONCLUSION: Indications for a multidisciplinary approach MMS were extensive defects and neuro/psych issues. Advantages include patient tolerance and single-stage procedure.

Human skin explant model for the investigation of topical therapeutics.

The development of in vitro and ex vivo models to mimic human illness is important not only for scientific understanding and investigating therapeutic approaches but also to mitigate animal testing and bridge the inter-species translational gap. While in vitro models can facilitate high-throughput and cost-efficient evaluation of novel therapeutics, more complex ex vivo systems can better predict both desirable and adverse in vivo effects. Here we describe an ex vivo cultured human skin explant model in which we have characterized pathological tissue integrity, barrier function and metabolic stability over time. Our findings suggest that human skin can be successfully cultured for pharmacodynamic use up to and beyond 9 days without any adverse physiological consequence.

An in vitro bioassay for evaluating the effect of inhaled bronchodilators on airway smooth muscle.

PURPOSE: The development of inhaled drug products is expensive and involves time-consuming pharmacokinetic (PK) and pharmacodynamic (PD) studies. There are few in vitro cell-based assays to evaluate the disposition and action of orally inhaled drugs to guide early product development and minimise risk. The aim of the present study was to develop a co-culture bioassay, combining an airway epithelial cell line (Calu-3) with cultured human primary airway smooth muscle cells (ASM), integrated with apparatus to deliver pharmaceutical aerosols. METHODS: An assay for measuring cyclic adenosine monophosphate (cAMP) in ASM derived from healthy donors was adapted to provide a biochemical surrogate for ASM relaxation. Concentration-response curves for cAMP were established for three drugs that elicit ASM relaxation: isoprenaline (ISO), forskolin (FOR) and salbutamol sulphate. The ASM bioassay was incorporated into a co-culture model in which air-interfaced Calu-3 cell layers, representing the permeability barrier of the airway epithelium, were grown on transwell inserts above ASM cells cultured in the well of the base-plate. The sensitivity of this bioassay to salbutamol delivered using different formulations and aerosol products was evaluated. RESULTS: ASM responded with concentration dependent increases in cAMP when exposed to 10-9 to 10-5 M ISO, FOR or salbutamol sulphate solutions for 15 or 30 min. Salbutamol formulated with different counter ions elicited differential cAMP responses in ASM (xinafoate > base = sulphate) suggesting that this bioassay could discriminate between formulations with different potency. A similar rank order of potency was observed for the different salbutamol salts when applied as aerosols to the co-culture model. DISCUSSION: We have developed a novel bioassay using human ASM in co-culture with human respiratory epithelial cells to better mimic various elements that contribute to the rate and extent of local drug availability in the lungs following topical administration. The bioassay offers an opportunity to investigate the factors determining the activity of inhaled bronchodilator drugs in a more biologically relevant system than that has previously been described and with further development and validation, this novel bioassay could provide a method to guide the more efficient development of inhaled bronchodilators, reducing the current reliance on in vivo studies.