Characterization of a Topically Testable Model of Burn Injury on Human Skin Explants.

Severe burn injuries remain a major health problem due to high rates of mortality, residual morbidity, and/or aesthetic damages. To find new therapies aimed at promoting a harmonious healing of skin burns, it is important to develop models which take into account the unique properties of the human skin. Based on previously described models of burn injury performed on human skin explants, we hypothesized that maintaining explants under constant tension forces would allow to more closely reproduce the pathophysiological processes of skin remodeling. We thus. Here, we set up and characterized an improved model of deep second-degree burn injury on ex vivo cultured human skin explants at air-liquid interface and maintained under conditions of constant tension forces. A spontaneous re-epithelialization of the lesion was observed 8 to 9 days post burn and was found to rely on the proliferation of basal keratinocytes at the wound edges. Collagen VII at the dermo-epidermal junction reformed along with the progression of re-epithelializatio and a synthesis of procollagen III was observed in the dermis at the wound site. These findings indicate that our model is suitable for the assessment of clinically-relevant therapies aimed at modulating the kinetics of re-epithelialization and/or the activation of fibroblasts following skin burn injuries. In this regard, we evaluated the use of a thermoreversible poloxamer hydrogel as a vehicle for topically-testable therapeutic molecules. Our data showed that, although useful for drug formulation, the p407/p188 poloxamer hydrogel induces a delay of skin re-epithelialization in humans skin explants submitted to experimental burn injury.

Development and characterization of Lyophilized Transparized Decellularized stroma as a replacement for living cornea in deep anterior lamellar keratoplasty.

Corneal disease is the second cause of blindness in developing countries, where the number of corneal grafts needed by far exceeds the number available. In industrialized countries, although corneas are generally available for keratoplasty, onto inflamed and vascularized host beds they are often rejected despite immune-suppression. A non-immunogenic, transparent, cytocompatible stroma is therefore required, which can be lyophilized for long-term conservation. Decellularization methods were tested on porcine corneal stromas before validation on human corneas. Decellularization and lyophilization led to opacification of the stroma, which could be reversed by soaking in 100% glycerol. Cell-depleted transparized stromas were then lyophilized (LTDC) to allow their long-term conservation and water content was measured. The ultrastructure of LTDC corneas was examined by transmission electron microscopy (TEM). Histocompatibility antigens were undetectable on LTDC stromas by antibody staining. Finally, cytocompatibility of LTDC stromas was demonstrated on an ex vivo model of anterior lamellar keratoplasty. Differential staining was used to monitor colonization of LTDC stromas by cells from the receiving cornea. Only SDS-based decellularization produced acellular porcine stromas. The lowest SDS concentration tested (0.1%) was validated on human corneas. Unlike lyophilized corneas, LTDC stromas without residual water, express no histocompatibility markers, although TEM revealed the presence of cellular debris in an ultrastructural arrangement of collagen fibers very close to that of native corneas. This structure is compatible with colonization by cells from the receiver cornea in an ex vivo lamellar graft model. Our procedure produced non-immunogenic, transparent stromas with conserved ultrastructure compatible with long-term conservation.

Dual 0.02% chlorhexidine digluconate - 0.1% disodium EDTA loaded thermosensitive ocular gel for Acanthamoeba keratitis treatment.

Poor bioavailability and low residence time limit the efficiency of conventional biguanide-based eye drops against Acanthamoeba keratitis. The aim of this work was to formulate an original anti-amoebic thermoreversible ocular gel combining biguanide and metalloproteases inhibitor - chelating agent. Chlorhexidine digluconate (CHX)-ethylenediaminetetraacetic acid disodium salt (Na2EDTA) were compounded in poloxamer 407 saline solution. 0.02% CHX - 0.1% Na2EDTA loaded thermosensitive ocular gel exhibited appropriate pH (5.73 ±â€¯0.06), iso-osmolality (314 ±â€¯5 mOsm/kg), viscosity (ranged between 15 and 25 mPa.s) and thermal gelation (26.5 °C and 33 °C) properties. Bioadhesion of gel was successfully tested onto isolated bovine eyes as well as the assessment of CHX penetration into the cornea. Intracorneal CHX concentration was found greater than trophozoite minimum amoebicidal concentration and minimal cysticidal concentration after 15-min and 2-h ocular exposure, respectively, while any CHX permeation through the cornea was detected (<51 ng/cm2/h). Improvement of CHX ocular bioavailability was attributed to probable solubilization of tear film lipid layer by poloxamer. In vitro efficiency of CHX-Na2EDTA ocular gel was confirmed from the drastic reduction of trophozoite and cyst survival (to 25% and 2%, respectively), confirming the potential of the multicomponent pharmaceutical material strategy for the treatment of Acanthamoeba keratitis.

Formulation, stability testing, and analytical characterization of melatonin-based preparation for clinical trial.

A new institutional clinical trial assessed the improvement of sleep disorders in 40 children with autism treated by immediate-release melatonin formulation in different regimens (0.5 mg, 2 mg, and 6 mg daily) for one month. The objectives of present study were to (i) prepare low-dose melatonin hard capsules for pediatric use controlled by two complementary methods and (ii) carry out a stability study in order to determine a use-by-date. Validation of preparation process was claimed as ascertained by mass uniformity of hard capsules. Multicomponent analysis by attenuated total reflectance Fourier transformed infrared (ATR-FTIR) of melatonin/microcrystalline cellulose mixture allowed to identify and quantify relative content of active pharmaceutical ingredients and excipients. Absolute melatonin content analysis by high performance liquid chromatography in 0.5 mg and 6 mg melatonin capsules was 93.6%±4.1% and 98.7%±6.9% of theoretical value, respectively. Forced degradation study showed a good separation of melatonin and its degradation products. The capability of the method was 15, confirming a risk of false negative <0.01%. Stability test and dissolution test were compliant over 18 months of storage with European Pharmacopoeia. Preparation of melatonin hard capsules was completed manually and melatonin in hard capsules was stable for 18 months, in spite of low doses of active ingredient. ATR-FTIR offers a real alternative to HPLC for quality control of high-dose melatonin hard capsules before the release of clinical batches.

High pressure jet injection of viscous solutions for endoscopic submucosal dissection (ESD): first clinical experience.

BACKGROUND: Long lasting elevation is a key factor during endoscopic submucosal dissection (ESD) and can be obtained by water jet injection of saline solution or by viscous macromolecular solutions. In a previous animal study, we assessed the Nestis Enki II system to combine jet injection and viscous solutions. In the present work, we used this combination in humans in different sites of the digestive tract. METHODS: We retrospectively report all of the consecutive ESD procedures performed with jet injection of viscous solutions in four centers. Information was collected about the lesion, the procedure, the histological result, and the outcomes for the patient. RESULTS: In total, 45 resections were completed by six operators: five experts and one beginner with only one previous experience in human ESD. Lesions were located in the esophagus (10), the stomach (11), the duodenum (1), the colon (1) and the rectum (22). Average maximal lesion diameter was 4.8 cm (SD 2.4, range 2 - 11 cm), average lesion surface area was 19.8 cm(2) (SD 17.7, range 2.2 - 72 cm(2)), and average duration of procedure was 79.9 min (SD 50.3 min, range 19 - 225 min). ESD could be conducted while the endoscope was retroflexed at its maximum in 26 cases. Four adverse events were observed: two diminutive perforations and two delayed bleeding occurrences treated conservatively. The R0 resection rate was 91.1 %. The catheter was obstructed in six occurrences of bleeding. CONCLUSION: Endoscopic submucosal dissection using high pressure injection of viscous macromolecular solutions is safe and effective in different parts of the digestive tract. It does not impede working with the endoscope in the maximal retroflexed position.

New easy handling and sampling device for bioavailability screening of topical formulations.

Biopharmaceutical assessment of topical drug formulations is widely carried out by using vertical diffusion cells (Franz type cell). Although Franz diffusion cell model is well designed for percutaneous absorption studies, the extent of drug penetration within the skin requires more adapted device. Recently, we have developed a new patented versatile, easy-to-use, and disposable diffusion cell called VitroPharma. In this study we have assessed the cutaneous bioavailability of caffeine as hydrophilic compound model using Franz diffusion cell and VitroPharma. The percutaneous absorption of caffeine assessed with Franz diffusion cell and VitroPharma was characterized by using (i) finite dose model and (ii) classical pharmacokinetic analysis. Furthermore, the follow-up of caffeine penetration within the skin was determined by sequential measurements of tissular drug concentration throughout the time of skin exposure with VitroPharma. However, classical experimental design using Franz diffusion cell involved unique determination of tissular concentration at the final point of skin exposure protocol. Finally, device equivalence between Franz diffusion cell and VitroPharma was claimed from percutaneous absorption data analysis. Concomitant assessment of dual penetration and permeation kinetics by using VitroPharma reinforced the understanding of skin drug delivery.

Antimicrobial nanocapsules: from new solvent-free process to in vitro efficiency.

Skin and mucosal infections constitute recurrent pathologies resulting from either inappropriate antiseptic procedures or a lack of efficacy of antimicrobial products. In this field, nanomaterials offer interesting antimicrobial properties (eg, long-lasting activity; intracellular and tissular penetration) as compared to conventional products. The aim of this work was to produce, by a new solvent-free process, a stable and easily freeze-dryable chlorhexidine-loaded polymeric nanocapsule (CHX-NC) suspension, and then to assess the antimicrobial properties of nanomaterials. The relevance of the process and the physicochemical properties of the CHX-NCs were examined by the assessment of encapsulation efficiency, stability of the nanomaterial suspension after 1 month of storage, and by analysis of granulometry and surface electric charge of nanocapsules. In vitro antimicrobial activities of the CHX-NCs and chlorhexidine digluconate solution were compared by measuring the inhibition diameters of two bacterial strains (Escherichia coli and Staphylococcus aureus) and one fungal strain (Candida albicans) cultured onto appropriate media. Based on the findings of this study, we report a new solvent-free process for the production of nanomaterials exhibiting antimicrobial activity, suitable stability, and easily incorporable as a new ingredient in various pharmaceutical products.

High-pressure jet injection of viscous solutions for endoscopic submucosal dissection: a study on ex vivo pig stomachs.

BACKGROUND: Long-lasting lifting is a key factor during endoscopic submucosal dissection (ESD) and can be obtained by water-jet injection of saline solution or by injection of viscous macromolecular solutions. Combination of the jet injection and the macromolecular viscous solutions has never been used yet. We assessed the ability of a new water-jet system to inject viscous solutions in direct viewing and in retroflexion. We compared jet injection of saline solution and hyaluronate 0.5 % to perform ESD on ex vivo pig stomachs in order to evaluate the benefits of macromolecular solutions when injected by a jet-injector system. METHODS: This is a prospective comparative study in pig stomachs. Using the jet injector, four viscous solutions were tested: hydroxyethyl starch, glycerol mix, hyaluronate sodic (0.5 %), and poloxamer mix. Ten ESDs larger than 25 mm (five in direct viewing and five in retroflexion) and one larger than 10 cm were performed with each solution. ESD with hyaluronate jet injection was then compared with ESD with saline jet injection by performing 50 ESDs in each group. A single, minimally-experienced operator conducted all the procedures. RESULTS: All 145 resections were complete, including all marking points with two perforations. Eleven jet ESDs per solution were conducted without any injection issue. In the second part of the study, when compared with saline, significant benefit of hyaluronate was observed on dissection speed (0.80 vs. 1.08 cm(2)/min, p < 0.001). CONCLUSION: This is the first report on a jet-injector system allowing injection of macromolecular viscous solutions even with retroflexed endoscope. Jet injection of macromolecular solutions can speed up dissection in comparison with saline, and should now be tested on humans.

Bladder tissue permeability and transport modelling of intravesical alum, lidocaine hydrochloride, methylprednisolone hemisuccinate and mitomycin C.

The aims of this study were to assess the tissue permeability of the bladder and to characterize the transport of four drugs displaying different physico-chemical properties and commonly used in intravesical delivery, through porcine bladder. The transport of aluminium through porcine bladder was assessed by using a vertical static diffusion cell. Lidocaine hydrochloride, methylprednisolone hemisuccinate and mitomycin C were tested by using three different experimental setups, including vertical static diffusion cell, microdialyseur and lab-patented device. Penetration results on different experimental setups were homogenous suggesting dependency on physico-chemical characteristics of drug and subsequent interaction with bladder wall structure. Oppositely, permeation varied consistently with experimental setup characteristics (i.e., permeation surface, receptor fluid volume and hydrodynamic). Mathematical modelling of drug transport through bladder wall is proposed considering scarce literature on this route of administration. Practical outcome of this study could drive compounding optimization towards improvement of safety and efficacy in patient undergoing intravesical administration.

Pharmaceutical and safety considerations of tablet crushing in patients undergoing enteral intubation.

Medication in patients undergoing enteral intubation addresses various challenging issues considering safety and treatment efficiency. Ideally, other routes of administration (i.e. intravenous or intramuscular routes) or especially dedicated formulations should be used. However, in absence of liquid dosage form, tablets or pills must be crushed and suspended in a vehicle before administration. The administration of oral dosage forms by enteral tube is usually performed by the nursing staff facing (i) pharmaceutical relevance of crushing, (ii) loss and concomitant aero-contamination of drug substance, (iii) drug-nutriment interactions and (iv) enteral feeding tube clogging. In the present study, different combinations of either open or confined crushing and suspending protocols were compared by taking into account the crushing yield, the stability and granulometry of the solid oral form suspension and finally the extend of aerosol contamination during crushing and suspending. All protocols exhibited comparable crushing efficiency and suspending properties, but significantly higher aerosolisation of tablet particles was observed in both open crushing and suspending protocol. Therefore, both confined crushing and suspending protocol constitutes an efficient, time saving and safe alternative to the absence of available liquid dosage form for intubated patients.