Biodegradable calcium carbonate carriers for the topical delivery of clobetasol propionate.

Inflammatory dermatoses represent a global problem with increasing prevalence and recurrence among the world population. Topical glucocorticoids (GCs) are the most commonly used anti-inflammatory drugs in dermatology due to a wide range of their therapeutic actions, which, however, have numerous local and systemic side effects. Hence, there is a growing need to create new delivery systems for GCs, ensuring the drug localization in the pathological site, thus increasing the effectiveness of therapy and lowering the risk of side effects. Here, we propose a novel topical particulate formulation for the GC clobetasol propionate (CP), based on the use of porous calcium carbonate (CaCO3) carriers in the vaterite crystalline form. The designed carriers contain a substantially higher CP amount than conventional dosage forms used in clinics (4.5% w/w vs. 0.05% w/w) and displayed a good biocompatibility and effective cellular uptake when studied in fibroblasts in vitro. Hair follicles represent an important reservoir for the GC accumulation in skin and house the targets for its action. In this study, we demonstrated successful delivery of the CP-loaded carriers (CP-CaCO3) into the hair follicles of rats in vivo using optical coherent tomography (OCT). Importantly, the OCT monitoring revealed the gradual intrafollicular degradation of the carriers within 168 h with the most abundant follicle filling occurring within the first 48 h. Biodegradability makes the proposed system especially promising when searching for new CP formulations with improved safety and release profile. Our findings evidenced the great potential of the CaCO3 carriers in improving the dermal bioavailability of this poorly water-soluble GC.

Clobetasol Propionate Is a Heme-Mediated Selective Inhibitor of Human Cytochrome P450 3A5.

The human cytochrome P450 (CYP) enzymes CYP3A4 and CYP3A5 metabolize most drugs and have high similarities in their structure and substrate preference. Whereas CYP3A4 is predominantly expressed in the liver, CYP3A5 is upregulated in cancer, contributing to drug resistance. Selective inhibitors of CYP3A5 are, therefore, critical to validating it as a therapeutic target. Here we report clobetasol propionate (clobetasol) as a potent and selective CYP3A5 inhibitor identified by high-throughput screening using enzymatic and cell-based assays. Molecular dynamics simulations suggest a close proximity of clobetasol to the heme in CYP3A5 but not in CYP3A4. UV-visible spectroscopy and electron paramagnetic resonance analyses confirmed the formation of an inhibitory type I heme-clobetasol complex in CYP3A5 but not in CYP3A4, thus explaining the CYP3A5 selectivity of clobetasol. Our results provide a structural basis for selective CYP3A5 inhibition, along with mechanistic insights, and highlight clobetasol as an important chemical tool for target validation.

Effect of physical stimuli on hair follicle deposition of clobetasol-loaded Lipid Nanocarriers.

Clobetasol propionate (CLO) is a potent glucocorticoid used to treat inflammation-based skin, scalp, and hair disorders. In such conditions, hair follicles (HF) are not only the target site but can also act as drug reservoirs when certain formulations are topically applied. Recently, we have demonstrated nanostructured lipid carriers (NLC) containing CLO presenting epidermal-targeting potential. Here, the focus was evaluating the HF uptake provided by such nanoparticles in comparison to a commercial cream and investigating the influence of different physical stimuli [i.e., infrared (IR) irradiation (with and without metallic nanoparticles-MNP), ultrasound (US) (with and without vibration) and mechanical massage] on their follicular targeting potential. Nanosystems presented sizes around 180 nm (PdI < 0.2) and negative zeta potential. The formulation did not alter skin water loss measurements and was stable for at least 30 days at 5 °C. Nanoparticles released the drug in a sustained fashion for more than 3 days and increased passively about 40 times CLO follicular uptake compared to the commercial cream. Confocal images confirmed the enhanced follicular delivery. On the one hand, NLC application followed by IR for heat generation showed no benefit in terms of HF targeting even at higher temperatures generated by metallic nanoparticle heating. On the other hand, upon US treatment, CLO retention was significantly increased in deeper skin layers. The addition of mechanical vibration to the US treatment led to higher follicular accumulation compared to passive exposure to NLC without stimuli. However, from all evaluated stimuli, manual massage presented the highest follicular targeting potential, driving more than double the amount of CLO into the HF than NLC passive application. In conclusion, NLC showed great potential for delivering CLO to HF, and a simple massage was capable of doubling follicular retention.

Reducing unpleasant side effects of topical 5-Fluorouracil treatment for actinic keratosis: a randomized controlled trial.

Introduction: 5-Fluorouracil (5-FU) for prophylactic treatment of diffuse actinic keratosis results in an exuberant inflammatory reaction, contributing to patient noncompliance and dissatisfaction.Design: This 5-week split-faced, double-blind, randomized controlled trial involved 30 subjects with diffuse facial AK who received twice daily 5-FU treatment for 2 weeks. This was followed by pre-randomized twice daily use of one of three topical interventions on one half of the face. TEWL, pH, and hydration were assessed on each quadrant of the face at all visits. Additionally, photographs were subjectively graded by three blinded trained observers.Results: Thirty subjects were enrolled, and had an average 27.1 (SD 11.8, range: 13-62) palpable AKs at baseline. Average resolution of baseline AK count was 98.1% by week 4. Clobetasol propionate is best at decreasing TEWL (p = .034), while petrolatum jelly most significantly improves hydration (p = .019) and erythema (p = .014). Though controlled release skin barrier emulsion trended towards improvement in TEWL (p = .17) and hydration (p = .19), there was no significant decrease in erythema (p = .257). Patient free-text response identified erythema as the most bothersome symptom.Conclusions: Given the low cost, wide availability, and ability to significantly reduce erythema, petrolatum should be used for post-5-FU treatment for diffuse AK.

Patients preferences for different corticosteroid vehicles are highly variable.

Introduction: Topical corticosteroids, available in an array of vehicles are used to control a variety of inflammatory skin diseases. Patients preferences for different vehicles may affect their willingness to use treatment. We assess corticosteroid vehicle preference and potential impact of topical characteristics on adherence and quality of life in patients with psoriasis.Methods: Subjects with psoriasis were recruited from Wake Forest University Dermatology Clinic. Subjects sampled desoximetasone 0.25% spray, betamethasone valerate 0.1% cream, triamcinolone acetonide 0.1% ointment, fluocinonide 0.05% gel, betamethasone valerate 0.1% lotion, clobetasol propionate 0.05% foam, and fluocinonide 0.05% solution in a predetermined randomized order. Subjects completed a Vehicle Preference Measure, Determinants of Adherence Measure, and a Determinants of Quality of Life Measure.Results: Patients preferences for the various products were highly variable. Regarding Determinants of Adherence, patients perception of absorption of the medication was ranked as 'quite important/extremely important' by 85% of total subjects. A majority of patients rated medication side effects as 'quite important/extremely important' when asked to consider topical characteristics effect on quality of life.Discussion: There was wide variation in patient preference for topical medication vehicles used for treating psoriasis. Several vehicle characteristics were considered important to adherence. Given the marked variation in vehicle preference, topical treatment should be individualized according to patients preferences.

Rapid Onset of Action in Patients With Moderate-to-Severe Plaque Psoriasis With Halobetasol 0.01%/Tazarotene 0.045% Fixed Combination.

BACKGROUND: Psoriasis is a chronic condition often managed with topical therapy. Patients have high expectations about the speed at which improvement is achieved, which then can have a marked impact on the patient's adherence to treatment. Recently, clinical data on a new fixed combination of halobetasol and tazarotene (HP/TAZ) have been presented. HP/TAZ lotion was statistically more effective than individual active ingredients or its vehicle, with a predictable safety profile. OBJECTIVES: Here we review the efficacy and tolerability data with a specific focus on the first two weeks of therapy. METHODS: Multicenter, randomized, double-blind, vehicle-controlled Phase 2 study in moderate or severe psoriasis (N=212). Subjects randomized (2:2:2:1 ratio) to receive halobetasol 0.01%/tazarotene 0.045% (HP/TAZ), individual active ingredients (HP or TAZ), or vehicle, once-daily for 8 weeks. Efficacy assessments included treatment success (defined as at least a 2-grade improvement from baseline in the IGA score and a score of 'clear' or 'almost clear'), and impact on individual signs of psoriasis (erythema, plaque elevation, and scaling) at the target lesion. RESULTS: As early as 2 weeks, HP/TAZ lotion demonstrated statistically significant superiority for treatment success over vehicle (P equals 0.047) and TAZ (P equals 0.029). By week 2, 47.5% of patients were 'mild', 'almost clear' or 'clear' compared with 33.3%, 16.9%, and 12.9% of patients treated with HP, TAZ, or vehicle, respectively; plaque elevation and scaling were significantly improved compared with HP, TAZ, or vehicle, and erythema was significantly improved compared with TAZ. Improvements in baseline itching (45.6%), dryness (42.2%), burning/stinging (55.9%) with HP/TAZ lotion at 2 weeks were similar to those seen with HP, and greater than that achieved with TAZ (30.8% [P equals 0.099], 35.4%, and 13.3%, respectively). CONCLUSION: The HP/TAZ fixed combination lotion provides rapid relief of psoriasis symptoms, with apparent benefits over both HP and TAZ by week 2. J Drugs Dermatol. 2018;17(8):863-868.

3D printing of a wearable personalized oral delivery device: A first-in-human study.

Despite the burgeoning interest in three-dimensional (3D) printing for the manufacture of customizable oral dosage formulations, a U.S. Food and Drug Administration-approved tablet notwithstanding, the full potential of 3D printing in pharmaceutical sciences has not been realized. In particular, 3D-printed drug-eluting devices offer the possibility for personalization in terms of shape, size, and architecture, but their clinical applications have remained relatively unexplored. We used 3D printing to manufacture a tailored oral drug delivery device with customizable design and tunable release rates in the form of a mouthguard and, subsequently, evaluated the performance of this system in the native setting in a first-in-human study. Our proof-of-concept work demonstrates the immense potential of 3D printing as a platform for the development and translation of next-generation drug delivery devices for personalized therapy.

Prolonged skin retention of clobetasol propionate by bio-based microemulsions: a potential tool for scalp psoriasis treatment.

Novel effective and cosmetically acceptable formulations are needed for the treatment of scalp psoriasis, due to the poor efficacy of the current products. The challenge in developing safe, efficient, and convenient delivery systems for this drug was addressed in the present work by formulating clobetasol propionate-loaded W/O microemulsions (MEs). Pseudo-ternary phase diagrams were constructed by using a combination of biocompatible and biodegradable excipients. Characterization studies demonstrated that selected MEs had suitable technological features such as being Newtonian fluids, possessing low viscosity, and high thermodynamic stability. Photomicrographs showed a significant alteration of the skin structure after treatment with MEs, and a preferential concentration of these in the stratum corneum and epidermis. These data, together with ex vivo permeation results, suggested an enhanced topical targeted effect due to an increased drug retention efficacy in the upper skin layers, as desired. Moreover, the bio-based excipients selected could contribute to the healing of the psoriatic scalp. In this way, the improvement of clobetasol efficacy is combined with the useful properties of the microemulsion components and with environmental safety.

The efficacy of short-term clobetasol lotion in the treatment of scalp psoriasis.

BACKGROUND: Scalp psoriasis can have a considerable impact on patients' quality of life and is considered difficult to treat. Treatment failure may, however, be due to poor adherence, as application of topical treatments to hair bearing areas is difficult and time consuming and also poor communication between physician and patient. OBJECTIVE: To assess the efficacy of short-term treatment of scalp psoriasis with topical clobetasol lotion. MATERIALS AND METHODS: Twelve patients with mild to severe scalp psoriasis were recruited for this study. Patients applied clobetasol 0.05% lotion twice daily for seven days. They were followed up with phone calls three days after starting the treatment. Skin hydration, transepidermal water loss (TEWL) and skin erythema were assessed noninvasively at baseline and end of study. RESULTS: One week after treatment, median PSI score decreased significantly (p = .002). There was also a significant decrease in median TEWL (p = .012) and increase in skin hydration one week after treatment (p = .010). Eighty three percent of patients were satisfied with treatment result and felt convenient with applying clobetasol lotion. LIMITATIONS: Lack of a long-term follow-up. CONCLUSIONS: Psoriasis is a long-term disease, and improving adherence in the short time could improve patient's adherence to treatment in long time.

Clobetasol-loaded nanostructured lipid carriers for epidermal targeting.

OBJECTIVES: The aim of this study was to investigate in vitro the epidermal targeting potential of clobetasol propionate-loaded nanostructured lipid carriers (CP-NLC) when compared to that of chitosan-coated (CP-NLC-C). METHODS: CP-NLC were prepared by microemulsion method and characterized by dynamic light scattering, transmission electron microscopy, in vitro release and permeation studies. To verify epidermal targeting, permeation studies were performed in two sets of experiments. For the first set, the skin was removed from the diffusion cell and stratum corneum (SC) was separated from the remaining skin (RS). For the second set, the whole epidermis (EP) was separated from the dermis (DER). CP quantification was performed in each skin layer. KEY FINDINGS: A novel clobetasol propionate-loaded NLC was produced with 1/5th of the drug dose used in commercial formulations and, even so, presented greater skin permeation. Both chitosan-coated and uncoated NLC enhanced the amount of CP in the epidermis more than 80-fold when compared to the commercial formulation (20.26 ± 2.77; 17.85 ± 0.49 and 0.22 ± 0.02 µg/cm(2) , respectively). Differently from chitosan-coated NLC, the uncoated NLC did not show dermal retention. CONCLUSIONS: NLC proved to be a system with potential for targeting drug delivery to the epidermal layer.

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 the In Vitro Drug Release from Lipid-Core Nanocapsules: a New Strategy Combining Dialysis Sac and a Continuous-Flow System.

The in vitro assessment of drug release from polymeric nanocapsules suspensions is one of the most studied parameters in the development of drug-loaded nanoparticles. Nevertheless, official methods for the evaluation of drug release from submicrometric carriers are not available. In this work, a new approach to assess the in vitro drug release profile from drug-loaded lipid-core nanocapsules (LNC) was proposed. A continuous-flow system (open system) was designed to evaluate the in vitro drug release profiles from different LNC formulations containing prednisolone or clobetasol propionate (LNC-CP) as drug model (LNC-PD) using a homemade apparatus. The release medium was constantly renewed throughout the experiment. A dialysis bag containing 5 mL of formulation (0.5 mg mL(-1)) was maintained inside the apparatus, under magnetic stirring and controlled temperature (37°C). In parallel, studies based on the conventional dialysis sac technique (closed system) were performed. It was possible to discriminate the in vitro drug release profile of different formulations using the open system. The proposed strategy improved the sink condition, by constantly renewing the release medium, thus maintaining the drug concentration farther from the saturated concentration in the release medium. Moreover, problems due to sampling errors can be easily overcome using this semi-automated system, since the collection is done automatically without interference from the analyst. The system proposed in this paper brings important methodological and analytical advantages, becoming a promising prototype semi-automated apparatus for performing in vitro drug release studies from drug-loaded lipid-core nanocapsules and other related nanoparticle drug delivery systems.

Growth and characterization of organic NLO material: clobetasol propionate.

Single crystals of clobetasol propionate (CP) have been grown by slow evaporation solution technique using mixed solvent of methanol-acetone. The grown crystals were subjected to single crystal X-ray diffraction analysis to confirm their lattice parameter and space group. The powder X-ray diffraction pattern of the grown CP has been indexed. Thermal analysis was performed to study the thermal stability of the grown crystals. Photoluminescence spectrum shows broad emission peak observed at 421 nm. Nonlinear optical studies were carried out for the grown crystal and second harmonic generation (SHG) efficiency was found in the crystal.

Quantification of halobetasol propionate and its impurities present in topical dosage forms by stability-indicating LC method.

A novel, sensitive, stability-indicating, gradient, reverse-phase high-performance liquid chromatographic method has been developed for quantitative determination of halobetasol propionate and its impurities in topical dosage forms. The chromatographic separation was achieved on a Phenomenex Synergi polar reverse phase, 250 × 4.6 mm, 4 µm column. Mobile phase A comprises a mixture of 0.01 M KH2PO4 buffer containing 0.2% 1-octane sulfonic acid sodium salt (pH 3.0), acetonitrile and methanol in the ratio 80:15:05 (v/v/v), respectively, and mobile phase B contains a mixture of 0.01 M KH2PO4 buffer containing 0.2% 1-octane sulfonic acid sodium salt (pH 3.0), acetonitrile and methanol in the ratio 20:70:10 (v/v/v), respectively. The flow rate is 0.8 mL min(-1). The column compartment temperature is set at 40°C and the detection wavelength is set at 240 nm. The resolutions between Halobetasol propionate and all the impurities are >2.0 for all pairs of compounds. The drug product was subjected to International Conference on Harmonization (ICH)-prescribed hydrolytic, oxidative, photolytic and thermal stress conditions. The method is validated as per the ICH guidelines with respect to specificity, linearity, limit of detection, limit of quantification, accuracy, precision, robustness and ruggedness.

Comparative pharmaceutical evaluation of brand and generic clobetasone butyrate ointments.

In the present study, we performed comprehensive pharmaceutical evaluation among an original clobetasone butyrate (CLB) ointment product and three generic products. Although spherocrystal images were observed under a polarizing microscope for only Kindavate®, the original product, distribution of active and inactive ingredients was chemically equivalent between the original and generic medicine by the attenuated total reflection infrared spectroscopy. These results suggest that the spherocrystals observed in Kindavate® are composed of hydrocarbon. On GC/MS, it was revealed that linear alkanes having 25-27 carbon atoms are densely present in Sun White®, the base used in Kindavate®. On the other hand, linear alkanes having 22-31 carbon atoms were broadly distributed in most other white petrolatums. In the CLB ointment products, the distribution equivalent of linear alkane to Sun White® was observed only in Kindavate®. Thus, the GC/MS method is extremely useful for identification of white petrolatum used in the ointment. A similar amount of CLB among the pharmaceutical products was detected in the skin tissue by skin accumulation test, although there were the differences in rheological properties and the quality of white petrolatum. The present results will be very useful for pharmacists in selecting medicine products that match the needs of the patient. Such pharmaceutical information will help spread objective knowledge about products in the future, and will contribute to the appropriate selection of medication.

Development of bullous pemphigoid after change of dialysis membrane.

A 75-year-old Japanese man presented with pruritic blisters and macules on his trunk and extremities. He had been on hemodialysis for 4 years because of chronic renal failure, and in recent months, a polymethylmethacrylate membrane had been used for dialysis. After a change in dialysis membrane to a cellulose triacetate membrane, pruritic tense blisters developed on the extremities in combination with marked blood eosinophilia. Physical examination showed erythematous macules and tense blisters on the trunk and extremities. A biopsy specimen of an erythematous macule showed subepidermal vesicles and eosinophils that attached to the dermal-epidermal junction. Serum level of eosinophilic cationic protein was elevated. From clinical, histological, and immunological findings, a diagnosis of bullous pemphigoid was made. New blisters continued to erupt during the period in which the patient used the cellulose triacetate membrane dialyzer, and even after the use of clobetasol propionate. It resolved only after the patient came back to the use of a synthetic membrane dialyzer. We discontinued the use of clobetasol propionate, and neither bullous eruptions nor blood eosinophilia recurred. These observations suggest that cellulose membrane may be involved in the development of bullous pemphigoid through activation of eosinophils in the blood and the skin lesion, as in the present case.

Characterization of suspected illegal skin whitening cosmetics.

An important group of suspected illegal cosmetics consists of skin bleaching products, which are usually applied to the skin of the face, hands and décolleté for local depigmentation of hyper pigmented regions or more importantly, for a generalized reduction of the skin tone. These cosmetic products are suspected to contain illegal active substances that may provoke as well local as systemic toxic effects, being the reason for their banning from the EU market. In that respect, illegal and restricted substances in cosmetics, known to have bleaching properties, are in particular hydroquinone, tretinoin and corticosteroids. From a legislative point of view, all cosmetic products containing a prohibited whitening agent are illegal and must be taken off the EU market. A newly developed screening method using ultra high performance liquid chromatography-time off flight-mass spectrometry allows routine analysis of suspected products. 163 suspected skin whitening cosmetics, collected by Belgian inspectors at high risk sites such as airports and so-called ethnic cosmetic shops, were analyzed and 59% were classified as illegal. The whitening agents mostly detected were clobetasol propionate and hydroquinone, which represent a serious health risk when repeatedly and abundantly applied to the skin.

Forced degradation studies of clobetasol 17-propionate in methanol, propylene glycol, as bulk drug and cream formulations by RP-HPLC.

A rapid, simple, stability-indicating forced degradation study of clobetasol 17-propionate was conducted using RP-HPLC. The method was used to analyze clobetasol 17-propionate in methanol, propylene glycol, and a cream formulation. Isocratic elution of clobetasol and its degradation products was achieved using a Nova-Pak® 4 µm C18 150 mm × 3.9 mm id cartridge column and a mobile phase of methanol: water (68:32 v/v) at a flow rate of 0.9 mL min(-1). Quantitation was achieved with UV detection at 239 nm. Nondegraded clobetasol was eluted at a retention time of 6.0 min. Clobetasol 17-propionate was subjected to different stress conditions viz., acidic, basic, heat, oxidation, light, and neutral hydrolysis. The greatest degradation occurred under strong base and oxidative conditions. Strong base-degraded clobetasol produced additional peaks at retention times of 1.8, 4.0, 5.0, and 8.0 min and clobetasol oxidation degradation peaks eluted at 2.2 and 24 min. Complete validation was performed for linearity, accuracy, and precision over the concentration range 0.15-15 µg mL(-1). All data were analyzed statistically and this RP-HPLC method proved to be accurate, precise, linear, and stability indicating for the quantitation of clobetasol 17-propionate in methanol, propylene glycol, and cream formulations.