Predicting Human Dermal Drug Concentrations Using PBPK Modeling and Simulation: Clobetasol Propionate Case Study.

Quantitative in silico tools may be leveraged to mechanistically predict the dermato-pharmacokinetics of compounds delivered from topical and transdermal formulations by integrating systems of rate equations that describe permeation through the formulation and layers of skin and pilo-sebaceous unit, and exchange with systemic circulation via local blood flow. Delivery of clobetasol-17 propionate (CP) from DermovateTM cream was simulated using the Transdermal Compartmental Absorption & Transit (TCATTM) Model in GastroPlus®. The cream was treated as an oil-in-water emulsion, with model input parameters estimated from publicly available information and quantitative structure-permeation relationships. From the ranges of values available for model input parameters, a set of parameters was selected by comparing model outputs to CP dermis concentration-time profiles measured by dermal open-flow microperfusion (Bodenlenz et al. Pharm Res. 33(9):2229-38, 2016). Predictions of unbound dermis CP concentrations were reasonably accurate with respect to time and skin depth. Parameter sensitivity analyses revealed considerable dependence of dermis CP concentration profiles on drug solubility in the emulsion, relatively less dependence on dispersed phase volume fraction and CP effective diffusivity in the continuous phase of the emulsion, and negligible dependence on dispersed phase droplet size. Effects of evaporative water loss from the cream and corticosteroid-induced vasoconstriction were also assessed. This work illustrates the applicability of computational modeling to predict sensitivity of dermato-pharmacokinetics to changes in thermodynamic and transport properties of a compound in a topical formulation, particularly in relation to rate-limiting steps in skin permeation. Where these properties can be related to formulation composition and processing, such a computational approach may support the design of topically applied formulations.

Determination of clobetasol propionate, tazarotene and tazarotenic acid in Bama mini-pig skin by UPLC-MS/MS: Application to pharmacokinetic and drug-drug interaction studies.

Tazarotene and clobetasol propionate are efficacious for the treatment of psoriasis. The plasma pharmacokinetic assessments of tazarotene or clobetasol propionate have been reported. However, the pharmacokinetic characteristics of tazarotene and clobetasol propionate in skin when used together have not been studied. In the present study, sensitive and rapid methods were developed for the determination of clobetasol propionate, tazarotene and its active metabolite tazarotenic acid in Bama mini-pig skin by UPLC-MS/MS. After homogenization and pretreatment of skin samples, the separation was performed on a WondaSiL C18 column (4.6 × 150 mm, 5 µm) for tazarotene and clobetasol propionate. The separation of tazarotenic acid was achieved on a BDS HYPERSIL C18 column (4.6 × 100 mm, 2.4 µm). All the analytes were quantified with positive electrospray ionization and multiple reactions monitoring mode. The assay was validated in the range of 22-1111 ng/g for tazarotene and clobetasol propionate, 2-111 ng/g for tazarotenic acid in skin samples. The methods were fully validated to meet the requirements for bioassay in accuracy, precision, recovery, reproducibility, stabilities and matrix effects, and successfully applied to evaluate the novel combination ointment of tazarotene and clobetasol propionate. The obtained intradermal content-time curves characterized the dermal absorption and metabolism features of the combination ointment. It was also found that there was no significant drug-drug interaction trend between tazarotene and clobetasol propionate. The obtained results would be essential for the development and clinical applications of this novel combination ointment.

Electrophoretic bottom up design of chitosan patches for topical drug delivery.

Clobetasol propionate (CP) is a high-potency corticosteroid, representing the standard of care for the symptomatic treatment of different skin disorders as well as oral mucosal diseases. Several topical delivery systems are available for treating oral lesions, but the ideal one is still lacking. In this work, we propose a novel class of chitosan (CS) patches, loaded with CP, for the topical treatment of inflammatory chronic oral diseases. Chitosan patches have been fabricated via electrophoretic deposition (EPD), by using a one-pot approach in order to load controlled quantity of CP. Optimized structures showed a water uptake in the range of 200-360% and mechanical properties that allow the design of flexible patches in wet state (E = 0.6 MPa and σbr = 0.55 MPa). Ultraviolet-visible (UV-Vis) spectroscopy was used for the evaluation of both loading and release profile of CP in CS patches. The CP loading has been tuned by adjusting CP concentration in deposition bath-in the range 0.002-0.12 mg cm-2-while releasing curves show an in vitro CP burst of about 80% in the first two hours. Overall, the obtained properties paved the way for the application of this new class of patches for the local oral release of CP.

In vitro penetration through the skin layers of topically applied glucocorticoids.

Corticoids are actives widely used in the treatment of skin diseases. This work aims to study the penetration of 3 corticoids (betamethasone, clobetasol, and flurandrenolide), their relationship with their Log D values and the effects of the vehicles. The 3 compounds were applied on a Franz-type diffusion cell in propylene glycol solution and their respective commercial creams and ointments. The active amounts found in the stratum corneum, epidermal, and dermal layers of the skin were investigated. Their diffusions were greatly affected by the formulation; moreover higher amounts of substance in the epidermis and dermis were detected in ointments than in creams. The enhancement effect of propylene glycol was also observed. The differences between the 3 substances could be related to their lipophilicity, molecular structure, and molecular weight. The more hydrophobic compounds (clobetasol and betamethasone) are present in higher amounts in the epidermis and dermis, while the hydrophilic compound (flurandrenolide) is mostly present in the receptor fluid.

Comparison of Clobetasol Propionate Generics Using Simplified In vitro Bioequivalence Method for Topical Drug Products.

BACKGROUND: The aim of this paper is to evaluate a simple in vitro skin penetration experiment in which the drug is extracted from the whole skin piece as a test valid for formulation screening and optimization during development process, equivalence assessment during quality control or postapproval after changes to the product. METHODS: Twelve clobetasol propionate (CP) formulations (six creams and six ointments, being five generics and one reference from each formulation type) from the local market were used as a model to challenge the evaluated methodology in comparison to in vitro skin penetration following tape-stripping for drug extraction. To support the results, physicochemical tests for pH, viscosity, density and assay, as well as in vitro release were performed. RESULTS: Both protocols, extracting the drug from the skin using the tape-stripping technique or extracting from the full skin were capable of differentiating CP formulations. Only one formulation did not present statistical difference from the reference drug product in penetration tests and only other two oitments presented equivalent release to the reference. The protocol is straightforward and reproducible. CONCLUSION: Results suggest the bioinequavalence of tested CP formulations reinforcing the necessity of such evaluations.

Effect of Different Skin Penetration Promoters in Halobetasol Propionate Permeation and Retention in Human Skin.

Halobetasol propionate (HB) is a potent synthetic corticosteroid used against inflammatory skin diseases, such as dermatitis, eczema, and psoriasis, among others. The aim of this study is to define how the presence of different skin penetration enhancers (nonane, menthone, limonene, azone, carene, decanol, linoleic acid and cetiol) affects the penetration and retention in skin of HB. To determine drug penetration through skin, 5% of each promoter was used in an ex vivo system with human skin on Franz cells. The results showed that the highest permeation occurs in the presence of menthone, followed by nonane. Permeation parameters were determined. The in vivo test was assessed, and the formulation containing HB-menthone presented better anti-inflammatory efficacy. These results are useful to generate a specific treatment according to each patient's needs, and the inflammatory characteristics of the disease.

Chromatographic method for clobetasol propionate determination in hair follicles and in different skin layers.

Clobetasol propionate (CLO) is a potent steroid used for the treatment of several dermatological diseases. Recent studies suggest its additional use in alopecia topical treatment, generating a demand for novel formulations with specific delivery into hair follicles. Hence, a selective analytical method for drug quantification in follicular structures and skin layers is required. For this, a simple HPLC-UV method was developed. Quantification was performed using a RP-C18 column (4.6 mm × 15 cm, 5 µm), with a mixture of methanol-acetonitrile-water (50:15:35 v/v) as mobile phase, a flow rate of 1.2 mL/min, oven temperature of 30°C, injection volume of 50 µL and detection at 240 nm. The optimized conditions enabled a 12 min running with CLO elution at 10.1 min and resolution of 2.424 from skin matrix interferences. Validation was performed in accordance with International Conference on Harmonization guidelines and fulfilled the criteria of selectivity, linearity (0.5-15.0 µg/mL), robustness, precision, accuracy and limits of detection and quantification (0.02 and 0.07 µg/mL, respectively). The validated method was successfully applied for CLO quantification following in vitro skin permeation experiments and differential tape-stripping for hair follicle deposition determination, demonstrating its suitability.

Kinetics of Clobetasol-17-Propionate in Psoriatic Lesional and Non-Lesional Skin Assessed by Dermal Open Flow Microperfusion with Time and Space Resolution.

PURPOSE: To evaluate the kinetics of topically applied clobetasol-17-propionate (CP-17) in lesional and non-lesional psoriatic skin when released from a commercially available low-strength cream using in vivo dermal open-flow microperfusion (dOFM). METHODS: Twelve patients received Dermovate® cream (CP-17, 0.05%) on small lesional and non-lesional skin test sites for 14 days, once daily. On day 1 and 14, dOFM samples were continuously taken in the dermis for 24 h post-dose and analyzed by LC-MS/MS. Probe depths were assessed by 50 MHz ultrasound scanning. RESULTS: Mixed-effects modelling identified skin condition, treatment duration and probe-depth as kinetics determining variables. The time- and depth-resolved intradermal data revealed (i) slower penetration of CP-17 into lesional than into non-lesional skin, (ii) normalized (faster) skin penetration after repeated dosing, and (iii) no CP-17 accumulation within the dermis independently of the skin condition. CONCLUSIONS: Intradermal investigation of a highly lipophilic drug released from low-strength cream was successfully performed by using dOFM and timely and spatially, i.e., probe-depth dependent, resolved kinetic data were delivered. These data support the assumption that the thickened psoriatic stratum corneum might act as trap compartment which lowers the skin penetration rate for lipophilic topical drugs.

Nanostructured lipid carriers (NLC) based controlled release topical gel of clobetasol propionate: design and in vivo characterization.

Nanostructured lipid carrier (NLC)-based gel was developed as a potential topical system for clobetasol propionate (CP) topical delivery for the treatment of eczema. The characterizations of the prepared NLC formulation for topical application on the skin were assessed by means of morphology (SEM), particle size distribution, zeta potential analysis, drug entrapment efficiency, and in vitro drug release studies to select the optimized NLC formulation. The optimized NLC formulation encompasses particle size of 137.9 nm with -20.5 mV zeta potential and 0.224 polydispersity index which indicates good stability of NLC dispersion. NLC formulation showed a good entrapment efficiency of 78.5 % ± 0.03 with cumulative in vitro release 85.42 % up to 24 h. The optimized NLC formulation was suitably gelled and characterized for rheology, drug content, ex vivo drug permeation studies, and drug release kinetics studies. The permeation study revealed that the permeability parameters like steady-state flux (Jss), permeability coefficient (Kp), and enhancement ratio were significantly higher for NLC-based gel formulation as compared to marketed formulation of clobetasol propionate. The value of r (2) (Korsmeyer-Peppas equation) indicated good linearity showing anomalous (non-Fickian) diffusion viz. drug release is controlled by more than one process, i.e., superposition of both phenomenon, the diffusion controlled as well as swelling controlled release. The anti-inflammatory activity of NLC gel via paw oedema technique showed a rapid onset of action, as well as a prolonged duration of action as compared with the marketed gel.

Nanocarriers for optimizing the balance between interfollicular permeation and follicular uptake of topically applied clobetasol to minimize adverse effects.

The treatment of various hair disorders has become a central focus of good dermatologic patient care as it affects men and women all over the world. For many inflammatory-based scalp diseases, glucocorticoids are an essential part of treatment, even though they are known to cause systemic as well as local adverse effects when applied topically. Therefore, efficient targeting and avoidance of these side effects are of utmost importance. Optimizing the balance between drug release, interfollicular permeation, and follicular uptake may allow minimizing these adverse events and simultaneously improve drug delivery, given that one succeeds in targeting a sustained release formulation to the hair follicle. To test this hypothesis, three types of polymeric nanocarriers (nanospheres, nanocapsules, lipid-core nanocapsules) for the potent glucocorticoid clobetasol propionate (CP) were prepared. They all exhibited a sustained release of drug, as was desired. The particles were formulated as a dispersion and hydrogel and (partially) labeled with Rhodamin B for quantification purposes. Follicular uptake was investigated using the Differential Stripping method and was found highest for nanocapsules in dispersion after application of massage. Moreover, the active ingredient (CP) as well as the nanocarrier (Rhodamin B labeled polymer) recovered in the hair follicle were measured simultaneously, revealing an equivalent uptake of both. In contrast, only negligible amounts of CP could be detected in the hair follicle when applied as free drug in solution or hydrogel, regardless of any massage. Skin permeation experiments using heat-separated human epidermis mounted in Franz Diffusion cells revealed equivalent reduced transdermal permeability for all nanocarriers in comparison to application of the free drug. Combining these results, nanocapsules formulated as an aqueous dispersion and applied by massage appeare to be a good candidate to maximize follicular targeting and minimize drug penetration into the interfollicular epidermis. We conclude that such nanotechnology-based formulations provide a viable strategy for more efficient drug delivery to the hair follicle. Moreover, they present a way to minimize adverse effects of potent glucocorticoids by releasing the drug in a controlled manner and simultaneously decreasing interfollicular permeation, offering an advantage over conventional formulations for inflammatory-based skin/scalp diseases.

Nanoencapsulation of Clobetasol Propionate Decreases Its Penetration to Skin Layers Without Changing Its Relative Skin Distribution.

An immunosuppressive effect with drug release control and higher NTPDase activity in the treatment of contact dermatitis was previously reported for a hydrogel containing 0.05% clobetasol propionate-loaded lipid-core nanocapsules (HG-LNC-CP) compared to a hydrogel containing the non-encapsulated drug (HG-CP). In order to investigate the factors underlying this different performance, we evaluated the in vitro skin permeation/penetration of CP from both formulations (HG-LNC-CP and HG-CP). CP did not permeate to the receptor medium during the experiment (24 h), but penetrated into the stratum corneum and viable skin (epidermis and dermis) in significant amounts after 24 h, regardless the type of the formulation. Comparing both formulations, although the relative amount of CP in each skin layer was not affected by the nanoencapsulation, HG-LNC-CP was able to reduce in 5.8, 6.9 and 3.7 times the amount of CP released into the stratum corneum, epidermis and dermis respectively. In this way, the higher effect of HG-LNC-CP previously observed could be due to the controlled drug penetration rate into the skin layers. Moreover, HG-LNC-CP reduces the chances of the corticosteroid to be absorbed systemically as the amount of CP reaching the dermis was reduced. The study reinforces the HG-LNC-CP as a promising dermatological nanomedicine for the treatment of skin disorders.

Assessing topical bioavailability and bioequivalence: a comparison of the in vitro permeation test and the vasoconstrictor assay.

PURPOSE: To compare the sensitivity of a pharmacokinetic assay, the in vitro permeation test (IVPT), with that of a pharmacodynamic assay, the human skin blanching or vasoconstrictor (VC) assay, in assessing the relative bioavailability of topical clobetasol propionate products. METHODS: The percutaneous absorption of clobetasol propionate from five commercial products was measured in vitro using cryopreserved human skin. The pharmacodynamic potency of the same five products was also assessed in vivo using the VC assay, the surrogate method by which regulatory authorities in the United States establish the bioequivalence of generic topical glucocorticoid products. RESULTS: IVPT found total clobetasol absorption varying ten-fold from highest to lowest product, whereas the VC assay found this same difference was less than two-fold. The coefficient of variation ranged from 78 to 126% in the VC assay, but only 30-43% for IVPT. Statistically, IVPT could separate the 5 products into three groups: 1) ointment, 2) cream and gel, 3) emollient cream and solution). Due to its greater variability as well as saturation of the pharmacodynamic response at higher flux levels, the VC assay found all products except the solution to be equipotent. CONCLUSIONS: IVPT was found to be substantially more sensitive and less variable than the VC assay for assessing clobetasol bioavailability.

Uptake and biological effects of synthetic glucocorticoids in common carp (Cyprinus carpio).

Uptake and biological effects of synthetic glucocorticoids (GCs) were analyzed using common carp (Cyprinus carpio). Fish were exposed to clobetasol propionate (CP) or clobetasone butyrate (CB) individually or in mixture at 1 µg L(-1) for 21 days. Bioconcentration factor (BCF) of CB was calculated as 100, and BCF of CP was less than 16. No effects were found in fish erythrocyte and leukocyte numbers and serum glucose levels after exposure to the selected GCs. On the other hand, serum concentrations of free amino acids significantly increased in GC-exposed groups. Thus, exposures to synthetic GCs at relatively low concentrations seemed to cause enhancement of protein degradation and subsequent increase of serum free amino acids without a corresponding increase in serum glucose levels, an effect which might be related to partial induction of gluconeogenesis by GC.

The impact of manufacturing variables on in vitro release of clobetasol 17-propionate from pilot scale cream formulations.

OBJECTIVES: The purpose of the study was to evaluate the effect of different homogenization speeds and times, anchor speeds and cooling times on the viscosity and cumulative % clobetasol 17-propionate released per unit area at 72 h from pilot scale cream formulations. A 2(4) full factorial central composite design for four independent variables were investigated. MATERIALS AND METHODS: Thirty pilot scale batches of cream formulations were manufactured using a Wintech® cream/ointment plant. The viscosity and in vitro release of CP were monitored and compared to an innovator product that is commercially available on the South African market, namely, Dermovate® cream. RESULTS AND DISCUSSION: Contour and three-dimensional response surface plots were produced and the viscosity and cumulative % CP released per unit area at 72 h were found to be primarily dependent on the homogenization and anchor speeds. An increase in the homogenization and anchor speeds appeared to exhibit a synergistic effect on the resultant viscosity of the cream whereas an antagonistic effect was observed for the in vitro release of CP from the experimental cream formulations. The in vitro release profiles were best fitted to a Higuchi model and diffusion proved to be the dominant mechanism of drug release that was confirmed by use of the Korsmeyer-Peppas model. CONCLUSION: The research was further validated and confirmed by the high prognostic ability of response surface methodology (RSM) with a resultant mean percentage error of (±SD) 0.17 ± 0.093 suggesting that RSM may be an efficient tool for the development and optimization of topical formulations.

Evaluation of the skin blanching of topically applied steroids using a chroma meter in animals.

We evaluated the utility of animal skins for determining the skin blanching of steroids. A Chroma Meter was used to determine the skin blanching of steroids. Hydrophilic creams containing clobetasol propionate (CP) or prednisolone (PS) were selected as model steroid formulations. Skin blanching, a*, was determined using a Chroma Meter after the application of 0.005, 0.01, 0.1, or 1.0% CP or PS hydrophilic cream to the back skin of guinea pigs and hairless rats for 24 h. The relationships between Δa*(6h) and the skin concentrations of the steroids were determined at 6 h after removal of the cream. Δa*(6h) was markedly decreased after the application of CP hydrophilic cream to guinea pigs, and a good linear relationship was observed between Δa*(6h) and skin concentration (r=0.98). In contrast, no relationship was observed between these parameters after the application of CP cream to the hairless rats. Although skin blanching was observed after PS cream application in guinea pigs, no relationship was observed between Δa*(6h) and skin concentration of PS in each animal. These results suggest that the skin blanching effect of CP in guinea pigs is greater than that of PS and that its blanching effect in guinea pigs was stronger than that in hairless rats. Guinea pigs were found to be a good animal model for determining the skin blanching produced by steroid creams. In addition, Chroma Meters can be effectively used in skin vasoconstrictive tests in guinea pigs.

Efficacy of clobetasol spray: factors beyond patient compliance.

Clobetasol 0.05% spray, a topical clobetasol propionate, is a non-greasy formulation that has shown increased clinical efficacy in a head-to-head comparison with foam formulation. Moreover, available data from randomized, controlled, double-blind trials suggests that clobetasol spray is, in fact, slightly more effective than most, if not all, other preparations of clobetasol. The fact that clobetasol spray is exceptionally easy to comply with may have played a major role in this outcome; however, other factors must be considered. These include vehicle metamorphosis post-application as well as vehicle and excipient effects on stratum corneum permeability. Basic concepts in topical drug delivery and how they apply to this spray vehicle may further explain the greater efficacy of clobetasol spray.

Pharmacokinetics study about topical clobetasol on oral mucosa.

BACKGROUND: Clobetasol is the most potent topical corticosteroid used in oral medicine for muco-cutaneous diseases. Several papers reported about patients with cushingoid appearance, suggesting an adrenal suppression related to clobetasol systemic absorption after local application. Owing to the lack of studies, our goal is to assess whether transmucosal assimilation, after its application on oral mucosa, really occurs and to define clobetasol pharmacokinetics profile. METHODS: Data were recorded by collecting blood samples both on 10 patients in clobetasol therapy and on 14 healthy volunteers instructed about standardized clobetasol applications. A new technique of analytical chemistry was employed to detect its serum concentrations. RESULTS: Clobetasol absorption was ascertained, showing a certain accumulation rate. Different levels have been found in relation to oral disease and individual features (as smoking habits and presence of oral mucosa erosion). CONCLUSIONS: Our study validates clobetasol systemic transmucosal absorption, also recommending a careful monitoring of patients in corticosteroid therapy to avoid local and systemic adverse effects.

Application of dermal microdialysis for the determination of bioavailability of clobetasol propionate applied to the skin of human subjects.

Dermal microdialysis was used to assess the bioavailability of a topical corticosteroid, clobetasol propionate, following application onto the skin of human subjects. The penetration of clobetasol propionate from a 4% m/v ethanolic solution applied onto 4 sites on one forearm of healthy human volunteers was studied. A lipid emulsion, Intralipid®, was used as the perfusate and linear microdialysis probes with a 2-kDa cutoff were inserted intradermally at the designated sites. The results indicated that Intralipid could be used as a suitable perfusate for in vivo microdialysis of this lipophilic drug of interest. Furthermore, the study clearly demonstrated the application of dermal microdialysis as a valuable tool to assess the bioavailability/bioequivalence of clobetasol propionate penetration into the skin following topical application.