Texturing formulations for uranium skin decontamination

Abstract

Context: Since no specific treatment exists in case of cutaneous contamination by radionuclides such as uranium, a nanoemulsion comprising calixarene molecules, known for their good chelation properties, was previously designed. However, this fluid topical form may be not suitable for optimal application on the skin or wounds.

Objective: To develop a texturing pharmaceutical form for the treatment of wounded skins contaminated by uranium.

Materials and methods: The formulations consisted in oil-in-water (O/W) nanoemulsions, loaded with calixarene molecules. The external phase of the initial liquid nanoemulsion was modified with a combination of thermosensitive gelifying polymers: Poloxamer and HydroxyPropylMethylcellulose (HPMC) or methylcellulose (MC). These new formulations were characterized then tested by ex vivo experiments on Franz cells to prevent uranyl ions diffusion through excoriated pig ear skin explants.

Results: Despite strong changes in rheological properties, the physico-chemical characteristics of the new nanoemulsions, such as the size and the zeta potential as well as macroscopic aspect were preserved. In addition, on wounded skin, diffusion of uranyl ions, measured by ICP-MS, was limited to less than 5% for both HPMC and MC nanoemulsions.

Conclusions: These results demonstrated that a hybrid formulation of nanoemulsion in hydrogel is efficient to treat uranium skin contamination.     

Calixarene‐Entrapped Nanoemulsion for Uranium Extraction from Contaminated Solutions

Accidental cutaneous contamination by actinides such as uranium occurring to nuclear power plant workers can lead to their dissemination in other tissues and induce severe damages. Until now, no specific emergency treatment for such contamination has been developed. The aim of the present work was to formulate a tricarboxylic calix[6]arene molecule, known to exhibit good affinity and selectivity for complexing uranium, within a topical delivery system for the treatment of skin contamination. Since calixarene was shown to reduce oil/water interfacial tension, we have designed an oil‐in‐water nanoemulsion, taking advantage of the small droplet size offering a high contact surface with the contaminated aqueous medium. Characterization of the calixarene nanoemulsion was performed by determination of the oily droplet size, zeta potential and pH, measured as a function of the calixarene concentration. The obtained results have confirmed the surface localization of calixarene molecules being potentially available to extract uranyl ions from an aqueous contaminated solution. In a preliminary experiments, the calixarene nanoemulsion was used for the removal of free uranium from an aqueous contaminated solution. Results showed that the calixarene nanoemulsion extracted up to 80 ± 5% of uranium, which demonstrates the potential interest of this delivery system for uranium skin decontamination. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1375–1383, 2010     

Toxicology and hazard evaluation of cyanide fumigation powders

Studies were conducted to assess potential handling hazards from the pesticidal use of HCN-liberating "cyanide fumigation powders". Simulations were conducted in enclosed chambers on the release of HCN vapor from wetted powder containing 40% NaCN/60% kaolin at application rates of 1 g powder/m3 of space (usual rate) and 5 g/m3 (overuse condition). With the overuse situation, HCN vapor concentrations may be rapidly attained that produce serious or lethal toxicity; with the lower application rate minor signs and symptoms of HCN vapor exposure toxicity may develop. The acute peroral LD50 (rat and rabbit) of fumigant formulation is reduced in proportion to the kaolin content, but kaolin does not modify the inherent toxicity of NaCN. A typical cyanide hazard exists from swallowing cyanide fumigant powder formulations. Lethal systemic toxicity was produced by contamination of the eye (rabbit) with powder formulation, which also caused a rapid onset of moderately severe conjunctivitis and keratitis. Applied to dry intact skin (rabbit) neither NaCN nor its kaolin formulation produced systemic toxicity. However, on moistened intact skin lethal amounts of cyanide were absorbed; but the kaolin content reduced the hazard in comparison with NaCN-alone applied to moist skin. With abraded dry skin there was no difference in lethal toxicity between NaCN-alone and its formulation; also, the toxicity of the formulation on abraded skin was three times that on intact moist skin. These finds indicate that the use of cyanide fumigant powder formulations may be hazardous by contact of powder with moist or abraded skin, contamination of the eye, swallowing, and inhalation of evolved HCN. There is a clear need for respiratory, cutaneous, and ocular protection when handling cyanide fumigant powder formulations.     

Reduction of renal uranium uptake by acetazolamide: the importance of urinary elimination of bicarbonate]

Acetazolamide was compared with bicarbonate for the treatment of contamination with uranium. Uranium was injected peritoneally in rats, and its distribution was investigated. Acetazolamide was three times more efficient than bicarbonate in reducing the renal content of uranium. On the other hand, it had no effect on hepatic or skeletal content. In this study, renal physiology provides the basis for understanding the mode of action of acetazolamide and bicarbonate. In this context, it is of interest to determine the alkalinity of the urine, with the aim of knowing whether bicarbonate is present to mobilize uranium.     

单纯形网格法优化黄芪甲苷纳米乳处方及其皮肤滞留量考察

目的: 优化黄芪甲苷纳米乳处方并考察其皮肤滞留量。方法: 绘制伪三元相图,确定各相比例。以载药量、平均粒径及多分散指数为评价指标,采用单纯形网格法优化纳米乳处方。采用Franz扩散池法考察皮肤滞留量。结果: 优化的处方为丙二醇单月桂酸甘油酯含量5%,混合乳化剂(聚氧乙烯氢化蓖麻油∶1,2-丙二醇,Km=2∶1)含量40%,水含量55%,制备的纳米乳平均粒径为(20.73±0.25) nm,多分散指数为0.183±0.01,载药量为(1.60±0.05) mg·mL^-1,响应方程预测的各指标值与实测值偏差均小于5%。与黄芪甲苷混悬液比较,纳米乳显著提高黄芪甲苷的皮肤滞留量(P<0.01)。结论: 建立的方法预测性好,可用于黄芪甲苷纳米乳处方优化,纳米乳可显著提高黄芪甲苷的皮肤滞留量。     

Fabrication,in-vitro characterization,and enhanced in-vivo evaluation of carbopol-based nanoemulsion gel of apigenin for UV-induced skin carcinoma

The aim of this study was to develop a potential novel formulation of carbopol-based nanoemulsion gel containing apigenin using tamarind gum emulsifier which was having the smallest droplet size, the highest drug content, and a good physical stability for Skin delivery. Apigenin loaded nanoemulsion was prepared by high speed homogenization method and they were characterized with respect to morphology, zeta potential, differential scanning calorimeter study, and penetration studies. In-vitro release studies and skin permeation of apigenin loaded nanoemulsion by goat abdominal skin was determined using Franz diffusion cell and confocal laser scanning microscope (CLSM). The cytotoxicity of the reported formulation was evaluated in HaCaT Cells (A) and A431 cells (B) by MTT assay. The nanoemulsion formulation showed droplet size, polydispersity index, and zeta potential of 183.31?nm, 0.532, and 31.9?mV, respectively. The nanoemulsions were characterized by TEM demonstrated spherical droplets and FTIR to ensure the compatibility among its ingredients. CLSM showed uniform fluorescence intensity across the entire depth of skin in nanocarriers treatment, indicating high penetrability of nanoemulsion gel through goatskin. The nanoemulsion gel showed toxicity on melanoma (A341) in a concentration range of 0.4–2.0?mg/ml, but less toxicity toward HaCaT cells. The carbopol-based nanoemulsion gel formulation of apigenin possesses better penetrability across goatskin as compared to marketed formulation. Hence, the study postulates that the novel nanoemulsion gel of apigenin can be proved fruitful for the treatment of skin cancer in near future.     

Influence of uranium speciation on normal rat kidney (NRK-52E) proximal cell cytotoxicity

Uranium is a naturally occurring heavy metal. Its extensive use in the nuclear cycle and for military applications has focused attention on its potential health effects. Acute exposures to uranium are toxic to the kidneys where they mainly cause damage to proximal tubular epithelium. The purpose of this study was to investigate the biological consequences of acute in vitro uranyl exposure and the influence of uranyl speciation on its cytotoxicity. NRK-52E cells, representative of rat kidney proximal epithelium, were exposed to uranyl-carbonate and -citrate complexes, which are the major complexes transiting through renal tubules after acute in vivo contamination. Before NRK-52E cell exposure, these complexes were diluted in classical or modified cell culture media, which can possibly modify uranyl speciation. In these conditions, uranium cytotoxicity appears after 16 h of exposure. The CI50 cytotoxicity index, the uranium concentration leading to 50% dead cells after 24 h of exposure, is 500 microM (+/-100 microM) and strongly depends on uranyl counterion and cell culture medium composition. Computer modeling of uranyl speciation is reported, enabling one to draw a parallel between uranyl speciation and its cytotoxicity.     

Role of the olfactory receptor neurons in the direct transport of inhaled uranium to the rat brain

Uranium presents numerous industrial and military uses and one of the most important risks of contamination is dust inhalation. In contrast to the other modes of contamination, the inhaled uranium has been proposed to enter the brain not only by the common route of all modes of exposure, the blood pathway, but also by a specific inhalation exposure route, the olfactory pathway. To test whether the inhaled uranium enter the brain directly from the nasal cavity, male Sprague–Dawley rats were exposed to both inhaled and intraperitoneally injected uranium using the ²³⁶U and ²³³U, respectively, as tracers. The results showed a specific frontal brain accumulation of the inhaled uranium which is not observed with the injected uranium. Furthermore, the inhaled uranium is higher than the injected uranium in the olfactory bulbs (OB) and tubercles, in the frontal cortex and in the hypothalamus. In contrast, the other cerebral areas (cortex, hippocampus, cerebellum and brain residue) did not show any preferential accumulation of inhaled or injected uranium. These results mean that inhaled uranium enters the brain via a direct transfer from the nasal turbinates to the OB in addition to the systemic pathway. The uranium transfer from the nasal turbinates to the OB is lower in animals showing a reduced level of olfactory receptor neurons (ORN) induced by an olfactory epithelium lesion prior to the uranium inhalation exposure. These results give prominence to a role of the ORN in the direct transfer of the uranium from the nasal cavity to the brain.     

Nanosuspension improves tretinoin photostability and delivery to the skin

The aims of this work were to improve cutaneous targeting and photostability of tretinoin by using nanosuspension formulation. Tretinoin is a drug widely used in the topical treatment of various dermatological diseases. The tretinoin nanosuspension was prepared by precipitation method and then characterized by photo correlation spectroscopy for mean size and size distribution, and by transmission electron microscopy for morphological studies. An oil in water tretinoin nanoemulsion was also prepared and used as a control. Dermal and transdermal delivery of both tretinoin nanosuspension and nanoemulsion were tested in vitro by using Franz diffusion cells and newborn pig skin. Photodegradation studies were carried out by UV irradiation (1 h, λ = 366 nm) of the tretinoin nanosuspension in comparison with the nanoemulsion and a methanolic solution of the drug. During 8 h percutaneous experiments, the nanosuspesion was able to localize the drug into the pig skin with a very low transdermal drug delivery, whereas the nanoemulsion greatly improved drug permeation. UV irradiation of the nanosuspension showed a great improvement of tretinoin stability in comparison with both controls. Overall results show that nanosuspension might be a useful formulation for improving tretinoin dermal delivery and stability.     

Skin permeation mechanism of aceclofenac using novel nanoemulsion formulation

The aim of the present study was to investigate the skin permeation mechanism of aceclofenac using a novel nanoemulsion formulation. An optimized oil-in-water nanoemulsion of aceclofenac was prepared by the spontaneous emulsification method. The optimized nanoemulsion contained 2% w/w aceclofenac, 10% w/w Labrafil, 5% w/w Triacetin, 35.33% w/w Tween 80, 17.66% w/w Transcutol P and 32% w/w distilled water. The skin permeation mechanism was evaluated by FTIR spectroscopy, DSC thermography, activation energy measurement and histopathological examination. FTIR spectra of skin treated with the nanoemulsion formulation indicated breaking of the hydrogen bond network at the head of ceramides. DSC thermograms indicated that intracellular transport could be a possible mechanism of permeation enhancement and that permeation occurred due to the extraction of SC lipids by the nanoemulsion. The significant decrease in activation energy for aceclofenac permeation across rat skin indicated that the SC lipid bilayers were significantly disrupted (p < 0.05). Photomicrography of skin showed disruption and extraction of lipid bilayers as distinct voids and empty spaces visible in the epidermal region. Overall these findings indicated that nanoemulsions can be successfully used to enhance skin permeation of drugs.     

Design, development and evaluation of novel nanoemulsion formulations for transdermal potential of celecoxib

The aim of the present study was to investigate the potential of nanoemulsion formulations for transdermal delivery of celecoxib (CXB). The in vitro skin permeation profile of optimized formulations was compared with CXB gel and nanoemulsion gel. Significant increase in the steady state flux (Jss), permeability coefficient (Kp) and enhancement ratio (Er) was observed in nanoemulsion formulations T1 and T2 (p < 0.05). The highest value of these permeability parameters was obtained in formulation T2, which consisted of 2% (m/m) of CXB, 10% (m/m) of oil phase (Sefsol 218 and Triacetin), 50% (m/m) of surfactant mixture (Tween-80 and Transcutol-P) and 40% (m/m) water. The anti-inflammatory effects of formulation T2 showed a significant increase (p < 0.05) in inhibition after 24 h compared to CXB gel and nanoemulsion gel on carrageenan-induced paw edema in rats. These results suggested that nanoemulsions are potential vehicles for improved transdermal delivery of CXB.     

原花青素纳米乳的制备及其质量评价*

目的:研制原花青素纳米乳制剂并对其进行质量评价。方法:采用伪三元相图法进行处方筛选,并考察纳米乳的理化性质、稳定性及安全性。结果:制备的原花青素纳米乳,在透射电镜下观察为球状液滴,平均粒径为40 nm,影响因素实验表明该纳米乳制剂稳定,并对完整皮肤无毒性和刺激性。结论:原花青素纳米乳制备简单,性质稳定,有望成为原花青素新制剂。     

In-vitro skin pharmacokinetics of acitretin: percutaneous absorption studies in intact and modified skin from three different species using different receptor solutions.

The aromatic synthetic retinoid acid derivative, acitretin, is efficacious in several cutaneous diseases. Its toxicological profile makes a topical form with no or reduced systemic adverse effects desirable. Direct application of a topical acitretin formulation might result in therapeutic skin concentrations at the site of the disease while minimizing systemic exposure. The present studies define the percutaneous absorption characteristics of acitretin from an isopropylmyristate formulation. We investigated, in-vitro, (1) the role of receptor solution variations, (2) the role of skin modifications, (3) the influence of skin from three different species on the absorption of topically applied acitretin and (4) the drug distribution within the skin. Addition of solubilizers (Polyethylenglycol-20 and albumin) to the receptor solutions improved the flux of acitretin through monkey skin, whereas the acitretin concentration in the skin was not affected by the various receptor solutions used. Acitretin flux through tape-stripped monkey skin and dermis was only slightly higher than through intact skin. Acitretin concentration in human skin was significantly higher than in rhesus monkey or guinea-pig skin. Topical application of acitretin can produce dermal concentrations in excess of those achieved by therapeutic oral doses.     

The effect of stress on the temporal and regional distribution of uranium in rat brain after acute uranyl acetate exposure

Long-term exposure to depleted uranium (DU) has been shown to increase brain uranium and alter hippocampal function; however, little is known about the short-term kinetics of DU in the brain. To address this issue, temporal and regional distribution of brain uranium was investigated in male Sprague-Dawley rats treated with a single intraperitoneal injection of 1 mg uranium/kg as uranyl acetate. Due to the inherent stress of combat and the potential for stress to alter blood-brain barrier permeability, the impact of forced swim stress on brain uranium distribution was also examined in this model. Uranium in serum, hippocampus, striatum, cerebellum, and frontal cortex was quantified by inductively coupled plasma-mass spectrometry (ICP-MS) at 8 h, 24 h, 7 d, and 30 d after exposure. Uranium entered the brain rapidly and was initially concentrated in hippocampus and striatum. While multiple phases of uranium clearance were observed, overall clearance was relatively slow and the uranium content of hippocampus, cerebellum, and cortex remained elevated for more than 7 d after a single exposure. Prior exposure to stress significantly reduced hippocampal and cerebellar uranium 24 h post-exposure and tended to reduce uranium in all brain regions 7 d after exposure. The application of stress appeared to increase brain uranium clearance, as initial tissue levels were similar in stressed and unstressed rats.     

Topical delivery of aceclofenac as nanoemulsion comprising excipients having optimum emulsification capabilities: preparation,characterization and in vivo evaluation

Objective: The aim of the present study was to investigate the potential of a nanoemulsion for topical delivery of aceclofenac using different excipients having optimum emulsifying ability rather than their solubilizing capacity.

Methods: The oil-in-water nanoemulsions were prepared by screening the excipients from the nanoemulsion region of pseudoternary phase diagram. The prepared nanoemulsions were subjected to different thermodynamic stability tests. The nanoemulsion formulations that passed thermodynamic stability tests were characterized for viscosity, droplet size, transmission electron microscopy, refractive index and in vitro skin permeation. The in vitro skin permeation profile of optimized nanoemulsion formulation (NE31, containing 23.85% Polyoxy-35-castor oil, 7.95% PEG 400 and 13.6% Triacetin) was compared with that of nanoemulsion gel (NG31) and marketed gel formulation (HIFENAC GEL (HIG)). In vivo anti-inflammatory efficacy studies were also carried out for NE31, NG31 and HIG.

Results: The significant (p < 0.001) increase in in vitro permeability and in vivo anti-inflammatory efficacy of the NG31 formulation was observed as compared with HIG formulation.

Conclusion: It can be concluded that the selection of surfactant and cosurfactant on the basis of their emulsification capabilities other than the solubilizing capacity of drug is an important criterion for the formulation of nanoemulsion.     

Preparation and in vivo evaluation of indomethacin loaded true nanoemulsions

Indomethacin, a potent nonsteroidal anti-inflammatory drug, has been used in the treatment of various kinds of pains, inflammation and arthritis. However, oral administration of indomethacin produces serious gastrointestinal adverse effects. Therefore the aim of the present investigation was to evaluate the anti-inflammatory effects, skin irritation, activation energy and histopathology of indomethacin from transdermally applied true nanoemulsion. The anti-inflammatory effects of true nanoemulsions were compared with marketed Indobene^® gel on carrageenan-induced paw edema in rats. Skin irritation tests were performed on Wistar rats for 14 days. The % inhibition value after 12 h application was significant for optimized formulation F6 (83) as compared to marketed Indobene^® gel (P<0.01). Results of skin irritation test indicated that developed true nanoemulsion is safe for human use. The significant decrease in activation energy (1.396 kcal/mol) for indomethacin across rat skin indicated that the stratum corneum lipid bilayers were significantly disrupted (P<0.05). From these results it was concluded that the developed nanoemulsion have great potential for transdermal application of indomethacin.     

Absorption, accumulation and biological effects of depleted uranium in Peyer's patches of rats

The digestive tract is the entry route for radionuclides following the ingestion of contaminated food and/or water wells. It was recently characterized that the small intestine was the main area of uranium absorption throughout the gastrointestinal tract. This study was designed to determine the role played by the Peyer's patches in the intestinal absorption of uranium, as well as the possible accumulation of this radionuclide in lymphoid follicles and the toxicological or pathological consequences on the Peyer's patch function subsequent to the passage and/or accumulation of uranium. Results of experiments performed in Ussing chambers indicate that the apparent permeability to uranium in the intestine was higher (10-fold) in the mucosa than in Peyer's patches ((6.21+/-1.21 to 0.55+/-0.35)x10(-6)cm/s, respectively), demonstrating that the small intestinal epithelium was the preferential pathway for the transmucosal passage of uranium. A quantitative analysis of uranium by ICP-MS following chronic contamination with depleted uranium during 3 or 9 months showed a preferential accumulation of uranium in Peyer's patches (1355% and 1266%, respectively, at 3 and 9 months) as compared with epithelium (890% and 747%, respectively, at 3 and 9 months). Uranium was also detected in the mesenteric lymph nodes ( approximately 5-fold after contamination with DU). The biological effects of this accumulation of depleted uranium after chronic contamination were investigated in Peyer's patches. There was no induction of the apoptosis pathway after chronic DU contamination in Peyer's patches. The results indicate no change in the cytokine expression (Il-10, TGF-beta, IFN-gamma, TNF-alpha, MCP-1) in Peyer's patches and in mesenteric lymph nodes, and no modification in the uptake of yeast cells by Peyer's patches. In conclusion, this study shows that the Peyer's patches were a site of retention for uranium following the chronic ingestion of this radionuclide, without any biological consequences of such accumulation on Peyer's patch functions.     

Uranium induces genomic instability and slows cell cycle progression in human lymphocytes in acute toxicity study

In the situation of radiation triage, accidental exposure to uranium, or uranium contamination in food or water; haematopoietic decline or bone marrow sickness is observed in the aftermath followed by other systemic effects. Most studies done previously have been on cytogenetic analysis in blood lymphocytes of uranium miners wherein causal relationship was difficult to be established. This study provides new insights into the minimum risk level of uranium to human lymphocytes, DNA damage induced and alterations in the cell cycle progression through 96-h acute toxicity study. Cytotoxicity studies by MTT assay and flow cytometry showed that uranyl nitrate concentration of 1280 μM lead to 50% cell death, 640 μM caused 25% death, 250 μM caused 10% cell death and 5 μM was the NOAEL. Uranium caused DNA damages in a dose dependent manner as evident from comet and CBMN assays. A marked increase in G2/M phase cells was observed in the test culture groups. Halting of cell cycle at G2/M checkpoint also signified the extent of double strand breaks and genetic instability with increasing uranium dose in this study. Better cell cycle responses and lower genetic damage index observed in lower dosage of exposure, suggests adaptability and repair responses in human lymphocytes. Together these results advance our understanding of uranium effects on mammalian cells.     

Antigenicity and cutaneous toxicity of N-(4′-(9-acridinylamino)-3-methoxyphenyl)-methanesulfonamide (AMSA; NSC-249992) in guinea pigs and rabbits

Dermal rashes appearing in personnel involved in the bulk formulation of the antineoplastic agent AMSA prompted this investigation of the allergenicity and cutaneous irritation potential of the drug in rabbits and guinea pigs. Maximization testing of AMSA in guinea pigs resulted in a 100% skin sensitization rate. A 14-day cutaneous irritation study using a modified Draize test did not show any potential of AMSA to produce skin irritation on intact or abraded skin. AMSA did not induce antibodies in rabbits which could be detected by passive hemagglutination, cutaneous anaphylaxis, Arthus reactivity, or delayed hypersensitivity in rabbits. AMSA also failed to sensitize guinea pigs for systemic anaphylaxis.     

Chemoprevention of skin cancer using low HLB surfactant nanoemulsion of 5-fluorouracil: a preliminary study

Abstract

Oral delivery of 5-fluorouracil (5-FU) is difficult due to its serious adverse effects and extremely low bioavailability. Therefore, the aim of present investigation was to develop and evaluate low HLB surfactant nanoemulsion of 5-FU for topical chemoprevention of skin cancer. Low HLB surfactant nanoemulsions were prepared by oil phase titration method. Thermodynamically stable nanoemulsions were characterized in terms of droplet size distribution, zeta potential, viscosity and refractive index. Selected formulations and control were subjected to in vitro skin permeation studies through rat skin using Franz diffusion cells. Optimized formulation F9 was subjected to stability and in vitro cytotoxic studies on melanoma cell lines. Enhancement ratio was found to be 22.33 in formulation F9 compared with control and other formulations. The values of steady state flux and permeability coefficient for formulation F9 were found to be 206.40?±?14.56?µg?cm^?2?h^?1 and 2.064?×?10^?2?±?0.050?×?10^?2?cm?h^?1, respectively. Optimized formulation F9 was found to be physical stable. In vitro cytotoxicity studies on SK-MEL-5 cancer cells indicated that 5-FU in optimized nanoemulsion is much more efficacious than free 5-FU. From these results, it can be concluded that the developed nanoemulsion might be a promising vehicle for chemoprevention of skin cancer.