Topical caffeine-loaded nanostructured lipid carriers for enhanced treatment of cellulite: A 32 full factorial design optimization and in vivo evaluation in rats

The goal of this study was the development and evaluation of semisolid caffeine (CAF) loaded nanostructured lipid carriers (NLCs) for topical treatment of cellulite. CAF-loaded NLC formulations were prepared via high-speed homogenization followed by ultrasonication. A 32 full factorial design was employed for formulation optimization. The total lipid content (%) and the liquid lipid content per total lipids (%) were chosen as factors, whereas particle size (PS), polydispersity index (PDI), zeta potential (|ZP|) and viscosity (VIS) were selected as responses. The design suggested CAF-NLC3 as the optimum formulation consisting of a total lipid content of 15% w/w (palmitic acid and soft paraffin/isopropyl myristate, 7:3 w/w) and a surfactant content of 10% w/w (Tween 80/lecithin, 8:1.2 w/w). CAF-NLC3 revealed PS, PDI, ZP, VIS and CAF content values of 318.8 nm, 0.253, -41.1 mV, 18.0 Pa.s and 97.57%, respectively. It showed a pseudoplastic rheological behavior, acceptable pH value (5.25), good spreadability (1.12 mm2/g) and spherical shape employing transmission electron microscopy. Differential scanning calorimetry and X-ray diffraction demonstrated the amorphization of CAF in CAF-NLC3. CAF-NLC3 remained stable for 3 months at room and refrigeration conditions. A single topical application of CAF-NLC3 on shaved abdominal skins of Wistar rats revealed enhanced skin retention of CAF by 2-fold and 1.4-fold after 4 h when compared with plain CAF gel (CAF-P) and marketed CAF gel (CAF-M), respectively. Furthermore, CAF-NLC3 exhibited a superior anti-cellulite activity in comparison with CAF-P and CAF-M through elevating extracellular matrix components (collagen 1, elastin and hyaluronic acid) and stimulating the brown adipose tissue thermogenesis via up-regulating UCP1 and PPAR-γ expression. In addition, CAF-NLC3 prominently increased lipolysis through HSL activity and decreased pro-inflammatory cytokines such as ICAM-1 and VCAM-1 after 30 days of treatment on a high fat diet-induced cellulite rat model. These findings were further confirmed by histopathological examination supported by morphometric analysis. Therefore, incorporation of CAF in a semisolid NLC formulation would be a promising cosmetic approach for the topical treatment of cellulite.

5-Aminolevulinic Acid-Hyaluronic Acid Complexes Enhance Skin Retention of 5-Aminolevulinic Acid and Therapeutic Efficacy in the Treatment of Hypertrophic Scar

Hypertrophic scar is a serious skin disorder, which reduces the patient's quality of life. 5-aminolevulinic acid (5-ALA)-mediated photodynamic therapy has been used to treat patients with hypertrophic scar. However, the poor skin retention of 5-ALA limited the therapeutic effect. In this study, we constructed the 5-ALA-hyaluronic acid (HA) complex to potentially prolong the skin retention of 5-ALA for improving the therapeutic efficacy. HA is a polysaccharide with viscoelasticity and the carboxyl groups could conjugate with amino groups of 5-ALA via electrostatic interaction. The protoporphyrin IX (PpIX) assay revealed that 5-ALA-HA complexes markedly enhanced the skin retention, resulting in increased generation and accumulation of endogenous photosensitizer PpIX. Furthermore, 5-ALA-HA complexes allowed PpIX to be maintained at a high level for 12 h, much longer than the 3 h of 5-ALA alone. And then, the accumulative PpIX induced by 5-ALA-HA in human hypertrophic scar fibroblasts (HSF) was triggered by laser irradiation to produce sufficient reactive oxygen species, leading to efficient necrosis and apoptosis of HSF. In vivo therapeutic efficacy study indicated that 5-ALA-HA effectively reduced the appearance and scar thickness, and the scar elevation index with 5-ALA-HA treatment was significantly lower than other groups, suggesting that the 5-ALA-HA-treated scar became flattened and was closely matched to the unwounded tissues. Moreover, 5-ALA-HA treatment markedly downregulated the gene expression levels of α-SMA and TGF-β1, demonstrating attenuated the scar formation and growth. Therefore, the 5-ALA-HA complex enhancing skin retention and PpIX accumulation at the lesion site provide a promising therapeutic strategy for hypertrophic scar.

QbD steered fabrication of Pullulan-Terminalia catappa-Carbopol®971P film forming gel for improved rheological, textural and biopharmaceutical aspects

In present work, a film forming gel (FFG) was developed through ingenious amalgamation of polymers: Pullulan, Terminalia catappa and Carbopol®971P ® for cutaneous delivery of clotrimazole (CTZ) employing D-optimal mixture design. The developed FFG possess pseudoplastic, viscoelastic, thixotropic characteristics leading to good spreadability (35.71 ± 1.72 g·s, work of shear; 452.73 ± 8.23 g, firmness). Upon solvent evaporation, FFG converted in situ into bioadhesive film (81.90 ± 3.24 g) leading to longer residence on skin surface, prolonged delivery and ~1.3 fold enhanced CTZ skin retention as compare to commercial cream as evident from biopharmaceutical analysis, which is ideal for skin infections treatment. The simulation analysis suggested ≥10 μg/mL (MIC against C. albicans) CTZ concentration maintained for 2 times the days in rat skin as well as human skin as compared to commercial cream. Overall, the developed FFG system ascertained to be promising delivery system for treatment of chronic skin conditions.

A molecular mechanism investigation of the transdermal/topical absorption classification system on the basis of drug skin permeation and skin retention

A transdermal/topical absorption classification system for the characterization of the systemic or local delivery of drugs is the theoretical basis for the design and evaluation of transdermal/topical formulations. A classification system was established on the basis of the in vitro and in vivo skin permeation/retention behaviors of 12 model drugs. Drug skin penetration/retention exhibited a significant correlation with physicochemical parameters (log K_O/W, molecular weight, polar surface area, and polarizability). Four representative model drugs were selected to clarify the molecular mechanisms of drug skin permeation/retention behaviors. The excellent lipid-disrupting effect and enhanced partitioning exhibited by propranolol (high permeation-high retention) and zolmitriptan (high permeation-low retention) via the formation of moderate H-bonds with skin lipids were proven by ATR-FTIR (Δν_asCH2 > 2 cm^-1), Raman spectra (ΔLPP, SPP > 0.2 nm), and X-ray scattering (lipid crystallization) and were supported by ¹³C NMR results. The low lipid miscibility of zolmitriptan (ΔH_{zolmitriptan-lipid} = 126.92 J/g) caused the low skin retention of this drug. High polarizabiltiy (α = 38.5 × 10^-24 cm³) and low H-bond forming capability (E_H-bond = 0 kcal/mol) restricted terbinafine (low permeation-high retention) in terms of partitioning (k_D-SC = 0.09). Diclofenac (low permeation-low retention) stabilized skin lipids through the formation of strong H-bonds and exhibited excessive drug-lipid miscibility (ΔH_{diclofenac-skin} = -128.73 J/g), thus restricting its skin absorption. This classification system reflects the most essential drug skin absorption characteristics and provides a theoretical basis for the design of transdermal/topical formulations.

Design and dermatokinetic evaluation of Apremilast loaded nanostructured lipid carriers embedded gel for topical delivery: A potential approach for improved permeation and prolong skin deposition

The present study aimed to develop Apremilast loaded nanostructured lipid carriers (NLCs) for topical delivery to overcome the limitations of oral therapy and increase the efficacy. Apremilast loaded NLCs were prepared by hot emulsification technique. The developed formulation was optimized by Box Behnken design and characterized for size, entrapment efficiency, and zeta potential. The selected formulation was investigated for in-vitro release, ex-vivo skin retention, dermatokinetic, psoriasis efficacy, in-vivo skin retention and skin irritation study. The NLCs characterization results showed its spherical shape with the particle size of 157.91 ± 1.267 nm (0.165 ± 0.017 PDI). The entrapment efficiency and zeta potential were found to be 69.144 ± 0.278% and -16.75 ± 1.40 mV, respectively. The in-vitro release study revealed a controlled release of Apremilast from NLCs up to 24 h. The ex-vivo study showed 3-fold enhanced skin retention compared to conventional gel preparation. The formulation depicted improved psoriasis efficacy indicating reduced TNF-α mRNA expression. The cytotoxicity and skin irritation study revealed the prepared formulation has no toxicity or irritation. The study depicts the NLCs loaded Apremilast can be explored for the topical delivery for treatment of psoriasis with improved skin retention and efficacy.

Dermatokinetic assessment of luliconazole-loaded nanostructured lipid carriers (NLCs) for topical delivery: QbD-driven design, optimization, and in vitro and ex vivo evaluations

The present study is concerned with the QbD-based design and development of luliconazole-loaded nanostructured lipid carriers (NLCs) hydrogel for enhanced skin retention and permeation. The NLCs formulation was optimized employing a 3-factor, 3-level Box-Behnken design. The effect of formulation variable lipid content, surfactant concentration, and sonication time was studied on particle size and % EE. The optimized formulation exhibited particle size of 86.480 ± 0.799 nm; 0.213 ± 0.004 PDI, ≥ - 10 mV zeta potential and 85.770 ± 0.503% EE. The in vitro release studies revealed sustained release of NLCs up to 42 h. The designed formulation showed desirable occlusivity, spreadability (0.748 ± 0.160), extrudability (3.130 ± 1.570), and the assay was found to be 99.520 ± 0.890%. The dermatokinetics assessment revealed the C_{max Skin} to be ~ 2-fold higher and AUC_0-24 to be ~ 3-fold higher in the epidermis and dermis of NLCs loaded gel in contrast with the marketed cream. The T_max of both the formulations was found to be 6 h in the epidermis and dermis. The obtained results suggested that luliconazole NLCs can serve as a promising formulation to enhance luliconazole's antifungal activity and also in increasing patient compliance by reducing the frequency of application.

Cetyltrimethylammonium bromide-nanocrystalline cellulose (CTAB-NCC) based microemulsions for enhancement of topical delivery of curcumin

Low bioavailability and poor water solubility have limited the utilization of curcumin in conventional dosing methods. As an alternative, microemulsions as drug carrier can improve curcumin delivery. A cetyltrimethylammonium bromide-nanocrystalline cellulose (CTAB-NCC)-based microemulsion was developed and its potential use as a topical delivery method for curcumin was investigated. The effect of microemulsion's particle size and its microstructure as well as the presence of the CTAB-NCC nanoparticle on the topical delivery of curcumin was studied. In vitro permeation studies showed higher penetration rate of curcumin from the oil-in-water type-microemulsions. The skin permeation profile of curcumin followed Higuchi release kinetics. Furthermore, use of the (CTAB-NCC)-based microemulsion enhanced curcumin accumulation in the skin and these system showed non cytotoxicity effect on L929 cell line. These results showed the potential of (CTAB-NCC)-based microemulsions as controlled-release topical systems for the delivery of curcumin and potentially other lipophilic drugs.

RETRACTED: Pluronic® F127 stabilized reduced graphene oxide hydrogel for the treatment of psoriasis: In vitro and in vivo studies

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editors. Significant similarities were noticed post-publication between this article and an article submitted to the journal on the same day, by an apparently unrelated research group: Hui Li, Yanlu Jia and Chunling Liu, Colloids and Surfaces B: Biointerfaces 195 (2020) 111259 https://doi.org/10.1016/j.colsurfb.2020.111259. Moreover, the authors did not respond to the journal request to comment on these similarities and to provide the raw data, and the Editors decided to retract the article. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and genuine. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process. Although this article was published earlier than the article from Colloids and Surfaces B: Biointerfaces 195 (2020) 111259, the Editors decided to retract this article given the concerns on the reliability of the data.

Investigating the skin penetration and wound healing properties of niosomal pentoxifylline cream

Wounds are defined as any injuries to the skin. Wounds can cause great inconvenience and health problems for the patients depending on the healing time and severity. This makes wound healing and the strategies to treat a wound or reduce their treatment time, an important concern in health care systems. Pentoxifylline (PTX) has been reported to facilitate the wound healing in systemic administration. Different cellular and immunological mechanisms have been reported and suggested regarding the promising effects of PTX. On the other hand, the topical application of PTX seems to improve its therapeutic efficiency by localizing the drug on the wound site. In this study, PTX-niosomes were prepared and characterized. Niosomes with Zavg of 150, 200, and 300 nm were incorporated into the base cold cream. In-vitro release of PTX from these formulations was obtained between 70 -100%. Ex-vivo penetration/retention studies showed that niosomal formulations (F₆ and F₇) increased penetration of PTX by 1.8 and 1.2 times, respectively in comparison with the PTX-conventional cream. Retention of PTX from both niosomal creams was about 2 times higher than the PTX-conventional cream. In -vivo studies on the full-thickness wound in BALB/c mice showed that PTX-niosomal creams shortened the duration of wound healing by two days compared to control groups (PTX-conventional cream, base cream, and no treatment). The final wound size in the niosomal cream-treated group was also significantly smaller than the control groups. Histological analysis of the wounds confirmed the results of in-vivo studies.

A human skin high-throughput formulation screening method using a model hydrophilic drug

Franz cell (FC) experiments in topical and transdermal drug development represent the gold standard in vitro method but require a relatively high quantity of human skin, are low-throughput, and are time-consuming to perform. To address these issues, we studied a micro-well plate-based screening method for permeability and retention that could enable the direct screening of large numbers of formulations simultaneously across human skin. Using freshly excised dermatomed human skin modified to reflect poor barrier function and a model hydrophilic compound, Sulforhodamine B (SRB), FC permeation and retention quantification was compared to the 96-well high-throughput system (HTS). The skin was analyzed using 2-photon microscopy to determine the drug distribution within the skin. A screen of 15 different formulations in triplicate in a single piece of human skin, using full factorial design was then conducted. Permeability of SRB across the skin as well as the drug distribution profile of SRB retained in the skin were similar for the FC and HTS system. The influence of different excipients on drug retention was observed in the full factorial formulation screen. The HTS method is promising for the investigation of large numbers of formulations and the influence of formulations changes in skin retention of drug.

Systematically optimized topical delivery system for Loperamide hydrochloride: Formulation design, in vitro and in vivo biopharmaceutical evaluation

This study aimed to develop a suitable topical delivery system containing diethylene glycol monoethyl ether (DGME) for Loperamide hydrochloride (Lop). Two factors, three levels Central-Composite design were applied by generating a quadratic polynomial equation to form contour plots and response surface for prediction of responses as two selected independent variables with EtOH-DGME ratio and EtOH concentration. The response variables flux and skin retention were determined in in vitro hairless mouse skin model. The selected optimum formulation was evaluated for the skin transport characteristics by developing dermatokinetic analysis model and the results demonstrated DGME improved the delivery of Lop into skin deep layers, which was further confirmed by confocal laser scanning microscopy (CLSM) study. In vitro skin permeation was found to have triphasic correlation with plasma AUC in the in vivo pharmacokinetic study. The in vitro–in vivo correlation enabled the prediction of pharmacokinetic profile of Lop from in vitro permeation results. Therefore, the optimum formulation capable of enhancing Lop intracutaneous depot could be a candidate for topical delivery of Lop as analgesics.

Topical iontophoretic delivery of ionizable, biolabile aciclovir prodrugs: A rational approach to improve cutaneous bioavailability

The objective was to investigate the topical iontophoretic delivery of a series of amino acid ester prodrugs of aciclovir (ACV-X, where ACV=aciclovir and X=Arg, Gly, Ile, Phe, Trp and Val) as a means to enhance cutaneous delivery of ACV. The newly synthesized prodrugs were characterized by (1)H NMR and high resolution mass spectrometry. Analytical methods using HPLC-UV were developed for their quantification and each method was validated. Investigation of solution stability as a function of pH showed that all ACV-X prodrugs were relatively stable in acid conditions at pH 2.0 and pH 5.5 for up to 8h but susceptible to extensive hydrolysis at pH 7.4 and under alkaline conditions (pH 10). No ACV-X hydrolysis was observed after contact for 2h with the external surface of porcine stratum corneum. However, there was significant hydrolysis following contact with the dermal surface of dermatomed porcine skin, in particular, for ACV-Arg. Passive transport of ACV and ACV-X prodrugs from aqueous solution after 2h was below the limit of detection. Iontophoresis of ACV at 0.5 mA/cm(2) for 2h led to modest ACV skin deposition (QDEP,ACV) of 4.6 ± 0.3 nmol/cm(2). In contrast, iontophoresis of ACV-X prodrugs under the same conditions produced order of magnitude increases in cutaneous deposition of ACV species, that is, QDEP,TOTAL=QDEP,ACV+QDEP,ACV-X. QDEP,TOTAL for ACV-Gly, ACV-Val, ACV-Ile, ACV-Phe, ACV-Trp and ACV-Arg was 412.8 ± 44.0, 358.8 ± 66.8, 434.1 ± 68.2, 249.8 ± 81.4, 156.1 ± 76.3, 785.9 ± 78.1 nmol/cm(2), respectively. The extent of bioconversion of ACV-X to ACV in the skin was high and the proportion of ACV present ranged from 81% to 100%. The skin retention ratio, a measure of the selectivity of ACV species for deposition over permeation after iontophoretic delivery of ACV-X prodrugs, was dependent on both the rate of transport and the susceptibility to hydrolysis of the prodrugs. Skin deposition of ACV and its six prodrugs were investigated further as a function of current density (0.125, 0.25 and 0.5 mA/cm(2)); the effect of duration of current application (5, 10, 30, 60 and 120 min) was evaluated using ACV-Arg and ACV-Ile. Iontophoresis of ACV-Arg and ACV-Ile at 0.25 mA/cm(2) for only 5 min resulted in the deposition of appreciable amounts of ACV (36.4 ± 5.7n mol/cm(2) and 40.3 ± 6.1 nmol/cm(2), respectively), corresponding to supra-therapeutic average concentrations in skin against HSV-1 or HSV-2. The results demonstrated that cutaneous bioavailability of ACV could be significantly improved after short-duration iontophoresis of ionizable, biolabile ACV-X prodrugs.