Comparative pharmacokinetic and biodistribution study of two distinct squalene-containing oil-in-water emulsion adjuvants in H5N1 influenza vaccines.

BACKGROUND: In recent years, there has been great interest from academia, industry and government scientists for an increased understanding of the mode of action of vaccine adjuvants to characterize the safety and efficacy of vaccines. In this context, pharmacokinetic (PK) and biodistribution studies are useful for quantifying the concentration of vaccine adjuvants in mechanistically or toxicologically relevant target tissues. METHODS: In this study, we conducted a comparative analysis of the PK and biodistribution profile of radiolabeled squalene for up to 336 h (14 days) after intramuscular injection of mice with adjuvanted H5N1 influenza vaccines. The evaluated adjuvants included an experimental-grade squalene-in-water (SQ/W) emulsion (AddaVax®) and an adjuvant system (AS03®) that contained squalene and α-tocopherol in the oil phase of the emulsion. RESULTS: The half-life of the initial exponential decay from quadriceps muscle was 1.5 h for AS03 versus 12.9 h for AddaVax. At early time points (1-6 h), there was about a 10-fold higher concentration of labeled squalene in draining lymph nodes following AS03 injection compared to AddaVax. The area-under-concentration curve up to 336 h (AUC0-336hr) and peak concentration of squalene in spleen (immune organ) was about 1.7-fold higher following injection of AS03 than AddaVax. The peak systemic tissue concentration of squalene from the two adjuvants, with or without antigen, remained below 1% of injected dose for toxicologically relevant target tissues, such as spinal cord, brain, and kidney. The pharmacokinetics of AS03 was unaffected by the presence of H5N1 antigen. CONCLUSIONS: This study demonstrates a rapid decline of AS03 from the quadriceps muscles of mice as compared to conventional SQ/W emulsion adjuvant, with an increased transfer to mechanistically relevant tissues such as local lymph nodes. Systemic tissue exposure to potential toxicological target tissues was very low.

Safety Assessment of Sorbitan Esters as Used in Cosmetics.

The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of 20 sorbitan esters; this report included sorbitan esters that were reviewed in 1985 and 2002, as well as 3 previously unreviewed sorbitan esters (sorbitan undecylenate, sorbitan sesquicaprylate, and sorbitan palmate). Most of the sorbitan esters are reported to function in cosmetics as surfactant-emulsifying agents. The Panel reviewed the data from previous sorbitan ester reports, as well as additional data included in this report, to determine the safety of these ingredients. The Panel concluded that the sorbitan esters included in this safety assessment are safe in cosmetics in the present practices of use and concentration.

Influence of Polysorbate 60 on Formulation Properties and Bioavailability of Morin-Loaded Nanoemulsions with and without Low-Saponification-Degree Polyvinyl Alcohol.

The aim of the present study was to investigate the influence of polysorbate 60 (Tween 60) on the development of morin-loaded nanoemulsions to improve the oral bioavailability of morin. Nanoemulsions were prepared using Tween 60 and polyvinyl alcohol (PVA) as emulsifiers, and medium chain triglycerides (MCT) as the lipid base. Low-saponification-degree PVA (LL-810) was also added to stabilize dispersed droplets. MCT-LL810 nanoemulsion containing LL-810 was prepared with a reduced amount of Tween 60. However, the area under the blood concentration-time curve (AUC) of MCT-LL810 (0.18) nanoemulsion containing a small amount of Tween 60 did not increase because the absorption of morin was limited by P-glycoprotein (P-gp)-mediated efflux. MCT-LL810 (0.24) nanoemulsion containing a large amount of Tween 60 showed the highest AUC, dispersed droplets containing Tween 60 may have been transported into epithelial cells in the small intestine, and P-gp transport activity appeared to be suppressed by permeated Tween 60. Based on the plasma concentration profile, dispersed droplets in MCT-LL810 (0.24) nanoemulsion permeated more rapidly through the mucus layer and the intestinal membrane than MCT (0.24) nanoemulsion without LL-810. In conclusion, a novel feature of Tween 60 incorporated into the dispersed droplets of a nanoemulsion interacting with P-gp was demonstrated herein. Dispersed droplets in MCT-LL810 (0.24) nanoemulsion containing LL-810 permeated rapidly through the mucus layer and intestinal membrane, and Tween 60 incorporated in dispersed droplets interacted with P-gp-mediated efflux, increasing the bioavailability of morin.

Ultrasmall, water dispersible, TWEEN80 modified Yb:Er:NaGd(WO4)2 nanoparticles with record upconversion ratiometric thermal sensitivity and their internalization by mesenchymal stem cells.

This work presents the synthesis by coprecipitation of diamond shaped Yb:Er:NaGd(WO4)2 crystalline nanoparticles (NPs) with diagonal dimensions in the 5-7 nm × 10-12 nm range which have been modified with TWEEN80 for their dispersion in water, and their interaction with mesenchymal stem cells (MSCs) proposed as cellular NP vehicles. These NPs belong to a large family of tetragonal Yb:Er:NaT(XO4)2 (T = Y, La, Gd, Lu; X = Mo, W) compounds with green (2H11/2 + 4S3/2 â†’ 4I15/2) Er-related upconversion (UC) efficiency comparable to that of Yb:Er:ß-NaYF4 reference compound, but with a ratiometric thermal sensitivity (S) 2.5-3.5 times larger than that of the fluoride. At the temperature range of interest for biomedical applications (∼293-317 K/20-44 °C) S = 108-118 × 10-4 K-1 for 20 at%Yb:5 at%Er:NaGd(WO4)2 NPs, being the largest values so far reported using the 2H11/2/4S3/2 Er intensity ratiometric method. Cultured MSCs, incubated with these water NP emulsions, internalize and accumulate the NPs enclosed in endosomes/lysosomes. Incubations with up to 10 µg of NPs per ml of culture medium maintain cellular metabolism at 72 h. A thermal assisted excitation path is discussed as responsible for the UC behavior of Yb:Er:NaT(XO4)2 compounds.

Pharmacokinetics and biodistribution of squalene-containing emulsion adjuvant following intramuscular injection of H5N1 influenza vaccine in mice.

Squalene is a component of oil-in-water emulsion adjuvants developed for potential use in some influenza vaccines. The biodistribution of the squalene-containing emulsion adjuvant (AddaVax™) alone and as part of complete H5N1 vaccine was quantified in mechanistically and toxicologically relevant target tissues up to 336 h (14 days) following injection into quadriceps muscle. At 1 h, about 55% of the intramuscularly injected dose of squalene was detected in the local quadriceps muscles and this decreased to 26% at 48 h. Twenty-four hours after the injection, approximately 5%, 1%, and 0.6% of the injected dose was detected in inguinal fat, draining lymph nodes, and sciatic nerve, respectively. The peak concentration for kidney, brain, spinal cord, bone marrow, and spleen was each less than 1% of the injected dose, and H5N1 antigen did not significantly alter the biodistribution of squalene to these tissues. The area-under-blood-concentration curve (AUC) and peak blood concentration (Cmax) of squalene were slightly higher (20-25%) in the presence of H5N1 antigen. A population pharmacokinetic model-based statistical analysis identified body weight and H5N1 antigen as covariates influencing the clearance of squalene. The results contribute to the body of knowledge informing benefit-risk analyses of squalene-containing emulsion vaccine adjuvants.

Polysorbate-80-coated, polymeric curcumin nanoparticles for in vivo anti-depressant activity across BBB and envisaged biomolecular mechanism of action through a proposed pharmacophore model.

Depression is a modern world epidemic. Its main causative factor is oxidative stress, as reported in study subjects. Natural products are yet to show significant therapeutic effects in comparison with synthetic drugs. Current study deals with the preparation of brain-targeted polysorbate-80-coated curcumin PLGA nanoparticles (PS-80-CUR-NP), and their characterisation via Spectral and optical methods. PS-80-CUR-NP were evaluated against the oxidative stress-mediated depressant (OSMD) activity via Force despair, Tail suspension tests and stress biomarker assay (SOD and catalase activity). A significant reduction in immobility (p < 0.01) in force despair and tail suspension test and a significant increase (p < 0.001 and p < 0.01) in SOD and catalase activity was found and compared with stress control, which confirmed the OSMD activity of PS-80-CUR-NP at 5 mg equivalent dose. Further, AUC(0.5-15 h) curve of brain homogenates estimated the curcumin concentration of 1.73 ng/g C max at T max 3 h via HPLC technique.

Enhanced oral delivery of risperidone through a novel self-nanoemulsifying powder (SNEP) formulations: in-vitro and ex-vivo assessment.

CONTEXT: The oral delivery of risperidone encounters a number of problems, such as pH dependent solubility and low bioavailability, due to its lipophilicity and aqueous insolubility. OBJECTIVE: To improve the solubility, dissolution and intestinal permeation thereby bioavailability of risperidone through a novel self-nanoemulsifying powder (SNEP) formulations. MATERIALS AND METHODS: Oleic acid, Tween® 20, PEG 600 and Aerosil® 200 were chosen as oil, surfactant, co-surfactant and carrier, respectively from solubility and emulsification studies. Ternary phase diagram was constructed to determine emulsifying region. RESULTS AND DISCUSSION: The Z-average and polydispersity Index of developed formulation was 83.1 nm and 0.306, respectively. Ex vivo permeation studies on isolated rat intestine indicated that the amount of risperidone permeated from SNEP formulation was increased around 4- and 1.8-fold than that of pure drug and marketed formulation, respectively. CONCLUSION: This developed SNEP formulations can be regarded as novel and commercially feasible alternative to the current risperidone formulations.

In Vitro Anti-inflammatory and Antimicrobial Activities of Azithromycin After Loaded in Chitosan- and Tween 20-Based Oil-in-Water Macroemulsion for Acne Management.

The objectives of the current investigation are (1) to prepare and characterize (particle size, surface charge (potential zeta), surface morphology by transmission electron microscopy, drug content, and drug release) the azithromycin (AZM, 100 mg)-loaded oil-in-water (o/w) macroemulsion, (2) to assess the toxicity of macroemulsion with or without AZM using RBC lysis test in comparison with AZM in phosphate buffer solution of pH 7.4, (3) to compare the in vitro antimicrobial activity (in Escherichia coli using zone inhibition assay) of AZM-loaded macroemulsion with its aqueous solution, and (4) to assess the in vitro anti-inflammatory effect (using egg albumin denaturation bioassay) of the AZM-loaded macroemulsion in comparison with diclofenac sodium in phosphate buffer solution of pH 7.4. The AZM-loaded macroemulsion possessed the dispersed oil droplets with a mean diameter value of 52.40 ± 1.55 µm. A reversal in the zeta potential value from negative (-2.16 ± 0.75 mV) to positive (+6.52 ± 0.96 mV) was noticed when AZM was added into the macroemulsion. At a 1:5 dilution ratio, 2.06 ± 0.03 mg of drug was released from macroemulsion followed by 1.01 ± 0.01 and 0.25 ± 0.08 mg, respectively, for 1:10 and 1:40 dilution ratios. Antimicrobial activity maintenance and significant reduction of RBC lysis property were noticed for AZM after loaded in the macroemulsion. However, an increment in the absorbance values for emulsion-treated samples in comparison to the control samples was noticed in the anti-inflammatory test. This speculates the potential of the AZM-loaded emulsion to manage inflammatory conditions produced at Acne vulgaris.

Fluorescent iodized emulsion for pre- and intraoperative sentinel lymph node imaging: validation in a preclinical model.

PURPOSE: To validate the usefulness of a newly developed tracer for preoperative gastric sentinel lymph node (LN) (SLN) mapping and intraoperative navigation after a single preoperative submucosal injection in rat and beagle models. MATERIALS AND METHODS: This study was approved by the Experimental Animal Ethical Committee of Yonsei University College of Medicine according to the eighth edition of the Guide for the Care and Use of Laboratory Animals published in 2011. An emulsion was developed that contained indocyanine green in iodized oil, which can be visualized with both computed tomography (CT) and near-infrared (NIR) optical imaging and has the property of delayed washout. This emulsion was injected into the footpad of rats (n = 6) and the gastric submucosa of beagles (n = 8). CT lymphography was performed. The degree of enhancement of popliteal LNs was measured in rats, and the enhancing LNs were identified and the degree of enhancement of the enhancing LNs was measured in beagles. Next, NIR imaging was performed in beagles during open, laparoscopic, and robotic surgery to identify LNs containing the fluorescent signals of indocyanine green. The enhanced LNs detected with CT lymphography and NIR imaging were matched to see if they corresponded. RESULTS: Preoperative CT lymphography facilitated SLN mapping, and 26 SLNs were identified in eight beagles. NIR imaging enabled high-spatial-resolution visualization of both SLNs and the intervening lymphatic vessels and was useful for intraoperative SLN navigation. CONCLUSION: SLN mapping with fluorescent iodized oil emulsion is effective and feasible for both CT and NIR imaging.

A first-generation physiologically based pharmacokinetic (PBPK) model of alpha-tocopherol in human influenza vaccine adjuvant.

Alpha (α)-tocopherol is a component of a new generation of squalene-containing oil-in-water (SQ/W) emulsion adjuvants that have been licensed for use in certain influenza vaccines. Since regulatory pharmacokinetic studies are not routinely required for influenza vaccines, the in vivo fate of this vaccine constituent is largely unknown. In this study, we constructed a physiologically based pharmacokinetic (PBPK) model for emulsified α-tocopherol in human adults and infants. An independent sheep PBPK model was also developed to inform the local preferential lymphatic transfer and for the purpose of model evaluation. The PBPK model predicts that α-tocopherol will be removed from the injection site within 24h and rapidly transfer predominantly into draining lymph nodes. A much lower concentration of α-tocopherol was estimated to peak in plasma within 8h. Any systemically absorbed α-tocopherol was predicted to accumulate slowly in adipose tissue, but not in other tissues. Model evaluation and uncertainty analyses indicated acceptable fit, with the fraction of dose taken up into the lymphatics as most influential on plasma concentration. In summary, this study estimates the in vivo fate of α-tocopherol in adjuvanted influenza vaccine, may be relevant in explaining its immunodynamics in humans, and informs current regulatory risk-benefit analyses.

Ultrastructural Visualization of Vaccine Adjuvant Uptake In Vitro and In Vivo.

Adjuvants are substances that enhance adaptive immune responses when formulated in a vaccine. Alum and MF59 are two vaccine adjuvants licensed for human vaccination. Their mode of action has not been completely elucidated. Here we show the first ultrastructural visualization of Alum and MF59 interaction with immune cells in vitro and in vivo. We observed that Alum is engulfed by cells as inclusions of laminae that are detectable within draining lymph nodes. MF59 is instead engulfed by cells in vitro as low-electron-dense lipid-like inclusions that display a vesicle pattern, as confirmed by confocal microscopy using fluorescently labeled MF59. However, lipid-like inclusions with different high- and low-electron-dense content are detected within cells of draining lymph nodes when injecting MF59. As high-electron-dense lipid-like inclusions are also detected upon injection of Alum, our results suggest that the low-electron-dense inclusions are formed by engulfed MF59, whereas the high-electron-dense inclusions are proper lipid inclusions. Thus, we demonstrated that vaccine adjuvants are engulfed as inclusions by lymph node cells and hypothesize that adjuvant treatment may modify lipid metabolism.

Cellular uptake of Nigella sativa oil-PLGA microparticle by PC-12 cell line.

The aim of this study is to investigate the cell uptake of Nigella sativa oil (NSO)-PLGA microparticle by neuron-like PC-12 cells in comparison to surfactants; hydrophilic (Tween 80 & Triton X100) and hydrophobic (Span 80). Solvent evaporation was used to precisely control the size, zeta potential and morphology of the particle. The results revealed varying efficiencies of the cell uptake by PC-12 cells, which may be partially attributed to the surface hydrophobicity of the microparticles. Interestingly, the uptake efficiency of PC-12 cells was higher with the more hydrophilic microparticle. NSO microparticle showed evidence of being preferably internalised by mitotic cells. Tween 80 microparticle showed the highest cell uptake efficiency with a concentration-dependent pattern suggesting its use as uptake enhancer for non-scavenging cells. In conclusion, PC-12 cells can take up NSO-PLGA microparticle which may have potential in the treatment of neurodegenerative disease.

Physico-chemical characterisation, cytotoxic activity, and biocompatibility studies of tamoxifen-loaded solid lipid nanoparticles prepared via a temperature-modulated solidification method.

CONTEXT: Solid lipid nanoparticles (SLNs) can efficiently and efficaciously incorporate anti-cancer agents. OBJECTIVE: To prepare and characterise tamoxifen (TAM)-loaded SLNs. MATERIALS AND METHODS: Glyceryl monostearate, Tween-80, and trehalose were used in SLNs. SLNs were tested via dynamic light scattering (DLS), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). RESULTS: Characterisation studies revealed SLNs of about 540 nm with a negative surface charge and confirmed the entrapment of TAM in the SLNs. The entrapment efficiency was estimated to be 60%. DISCUSSION: The in vitro drug release profile demonstrated a gradual increase followed by a release plateau for several days. A drug concentration-dependent increase in cytotoxic activity was observed when the SLNs were evaluated in cell cultures. CONCLUSION: Biocompatible and stable lyophilised SLNs were successfully prepared and found to possess properties that may be utilised in an anti-cancer drug delivery system.

Self nano-emulsifying simvastatin based tablets: design and in vitro/in vivo evaluation.

The aim of this work is to improve the oral bioavailability of poorly water soluble drug, simvastatin (SV) through combining the advantages of self-nanoemulsifying systems (SNEs) and tablets. Ternary phase diagram was constructed using Labrafil, Tween 80 and Transcutol, in order to evaluate self-nanoemulsification domain. The particle size distribution and zeta potential of the prepared systems were evaluated using Malvern Zetasizer. Liquisolid powders were prepared using Aeroperl(®) as a coating material and Avicel(®) or Starch 1500 as carrier materials, the powder flow properties were then evaluated. Compressed SV SNE based tablets were evaluated regarding their physical characteristics, in-vitro release properties as well as in-vivo pharmacokinetic evaluation in six healthy human volunteers using a validated LC/MS/MS method. The in-vitro release results revealed that the developed SNE based tablets improved the release of SV significantly, compared to commercially available SV tablets (Zocor(®)). The optimal SV SNE tablet formulation was S3St10 (10% Labrafil, 60% Tween 80, and 30% Transcutol). The in-vivo evaluation of S3St10 revealed that rapid and enhanced absorption of SV could be obtained from the SNE based tablet, with a 1.5 fold increase in bioavailability than that obtained after administration of Zocor(®). Hence such an approach could be promising in improving the bioavailability of SV.

Low molecular weight polyethylenimine-graft-Tween 85 for effective gene delivery: synthesis and in vitro characteristics.

The development of safe and efficient gene delivery systems is still a challenge for successful gene therapy. In this work, low molecular weight polyethylenimine (PEI 2K) was modified by Tween 85, which bears three oleate chains. Tween 85 modified PEI 2K (TP) could condense DNA efficiently, and TP/DNA complexes (TPCs) showed high resistance to salt-induced aggregation and enzymatic degradation. In addition, TP did not show the obvious cytotoxicity. The introduction of Tween 85 led to a significant increase in the cellular uptake of complexes with higher transfection efficiency, which was strongly inhibited by the addition of free Tween 85 in MCF-7/ADR cells, but not in MCF-7 cells. These results indicated that TP could be a potentially safe and effective copolymer for gene delivery, and TPCs could be taken up mainly by Tween 85-mediated endocytosis in MCF-7/ADR cells.

Effect of phospholipid-based formulations of Boswellia serrata extract on the solubility, permeability, and absorption of the individual boswellic acid constituents present.

Boswellia serrata gum resin extracts are used widely for the treatment of inflammatory diseases. However, very low concentrations in the plasma and brain were observed for the boswellic acids (1-6, the active constituents of B. serrata). The present study investigated the effect of phospholipids alone and in combination with common co-surfactants (e.g., Tween 80, vitamin E-TPGS, pluronic f127) on the solubility of 1-6 in physiologically relevant media and on the permeability in the Caco-2 cell model. Because of the high lipophilicity of 1-6, the permeability experiments were adapted to physiological conditions using modified fasted state simulated intestinal fluid as apical (donor) medium and 4% bovine serum albumin in the basolateral (receiver) compartment. A formulation composed of extract/phospholipid/pluronic f127 (1:1:1 w/w/w) increased the solubility of 1-6 up to 54 times compared with the nonformulated extract and exhibited the highest mass net flux in the permeability tests. The oral administration of this formulation to rats (240 mg/kg) resulted in 26 and 14 times higher plasma levels for 11-keto-ß-boswellic acid (1) and acetyl-11-keto-ß-boswellic acid (2), respectively. In the brain, five times higher levels for 2 compared to the nonformulated extract were determined 8 h after oral administration.

Preparation and evaluation of andrographolide-loaded microemulsion.

Andrographolide has a low aqueous solubility and oral bioavailability, which limits its clinical application. Reform the dosage forms of andrographolide to improve its aqueous solubility and oral bioavailability. The formulation, characterisation, stability, anti-inflammatory effect, pharmacokinetics and oral toxicity of andrographolide-loaded microemulsion, were studied. An formulation of O/W microemulsion consisting of an oil phase of isopropyl myristate, a surfactant phase of Tween 80, a co-surfactant of alcohol, and water was found to be ideal, with mean droplet size of 15.9 nm, a high capacity of solubilisation for andrographolide (8.02 mg mL(-1)). Such an andrographolide-loaded microemulsion is stable by monitoring the time, temperature and gravity-dependent change, and has a much better anti-inflammatory effect and a higher biological availability than andrographolide tablets. Besides, it also shows a very low acute oral toxicity. The andrographolide-loaded microemulsion is a promising dosage form of andrographolide.

[Advance of polysorbate 80 for injection accessories].

Polysorbate 80 for injection accessories is one of the main reactions of clinical adverse to which may be leaded by a variety of traditional Chinese medicine injection. In this review, on the basis of literature research and experimental studies, polysorbate 80 are summarized in areas which conclude the chemical structure, basic nature,quality standards, pharmacological activity, safety evaluation and toxicity studies. The review aimed to provide theoretical basis for the rational selections of Chinese medicine, safe and efficient usages of injection accessories, and to promote healthy development of traditional Chinese medicine injections.

New potential application of hydroxypropyl-ß-cyclodextrin in solid self-nanoemulsifying drug delivery system and solid dispersion.

The purpose of this study was to use hydroxypropyl-ß-cyclodextrin (HP-ß-CD) as a novel carrier in solid SNEDDS and solid dispersions to enhance the solubility and oral bioavailability of poorly water-soluble dexibuprofen. The novel dexibuprofen-loaded solid SNEDDS was composed of dexibuprofen, corn oil, polysorbate 80, Cremophor® EL, and HP-ß-CD at a weight ratio of 45/35/50/15/100. This solid SNEDDS spontaneously formed a nano-emulsion with a size of approximately 120 nm. Unlike the conventional solid SNEDDS prepared with colloidal silica as a carrier, this dexibuprofen-loaded solid SNEDDS exhibited a spherical structure. Similar to the dexibuprofen-loaded solid dispersion prepared with HP-ß-CD, the transformation of the crystalline drug to an amorphous state with no molecular interactions were observed in the solid SNEDDS. Compared to the solid dispersion and dexibuprofen powder, solid SNEDDS significantly enhanced drug solubility and AUC. Therefore, HP-ß-CD is a novel potential carrier in SNEDDS for improving the oral bioavailability of dexibuprofen.

Nanoemulsions containing Garcinia mangostana L. pericarp extract for topical applications: Development, characterization, and in vitro percutaneous penetration assay.

A highly stable oil-in-water nanoemulsion for topical applications, containing mangostins extracted from the pericarp of mangosteen (Garcinia mangostana L.), is a promising strategy to protect mangostins as well as to improve penetration of these important antioxidants through the skins. Nanoemulsions consisted of virgin coconut oil as the oil phase, Tween-80 and Span-80 as surfactants, and xanthan gum as the thickening agent, were prepared using the high-energy and low-energy emulsification methods. The nanoemulsions that were stable up to 28 days had oil droplet diameter of 220 nm to 353 nm and zeta potential of -46.9 mV to -63.7 mV. The accelerated stability test showed that the most stable nanoemulsions were those prepared using the low-energy emulsification method with an estimated shelf life of eleven months, composed of 11% oil phase, 17% surfactant, and 72% aqueous phase. The in vitro percutaneous penetration test for the nanoemulsion with added xanthan gum provided high cumulative skin penetration of mangostins of up to 114 µg/cm2. The results of this study indicate that virgin coconut oil-based nanoemulsions containing mangostins, prepared using the low-energy emulsification method, stabilized by xanthan gum and mixed at 40°C can prospectively be used for topical applications.