Physical Ageing of Amorphous Poly(lactic acid)-Indapamide System Studied by Differential Scanning Calorimetry.

The process of isothermal and non-isothermal physical ageing of amorphous polylactide (PLA) with the active pharmaceutical ingredient, indapamide (IND), was investigated. A PLA-IND system with a 50/50 weight ratio was obtained and characterized using differential scanning calorimetry (DSC). In the 50/50 (w/w) mixture, two glass transitions were observed: the first at 64.1 ± 0.3 °C corresponding to the glass transition temperature (Tg) of PLA, and the second at 102.6 ± 1.1 °C corresponding to the Tg of IND, indicating a lack of molecular mixing between the two ingredients. The PLA-IND system was subjected to the isothermal physical ageing process at different ageing temperatures (Ta) for 2 h. It was observed that the highest effect of physical ageing (enthalpy relaxation change) on IND in the PLA-IND system occurred at Ta = 85 °C. Furthermore, the system was annealed for various ageing times at 85 °C. The relaxation enthalpies were estimated for each experiment and fitted to the Kohlrausch-Williams-Watts (KWW) equation. The KWW equation allowed for the estimation of the relaxation time and the parameter describing the distribution of relaxation times of the isothermal physical ageing process of IND in the PLA-IND system. The physical ageing of the PLA-IND mixture (50/50) was also discussed in the context of heat capacity. Moreover, the activation energy and fragility parameters were determined for the PLA-IND (50/50) system.

Phototoxic or Photoprotective?-Advances and Limitations of Titanium (IV) Oxide in Dermal Formulations-A Review.

The widespread role of titanium (IV) oxide (TiO2) in many industries makes this substance of broad scientific interest. TiO2 can act as both a photoprotector and photocatalyst, and the potential for its role in both applications increases when present in nanometer-sized crystals. Its sunlight-scattering properties are used extensively in sunscreens. Furthermore, attempts have been made to incorporate TiO2 into dermal formulations of photolabile drugs. However, the propensity to generate reactive oxygen species (ROS) rendering this material potentially cytotoxic limits its role. Therefore, modifications of TiO2 nanoparticles (e.g., its polymorphic form, size, shape, and surface modifications) are used in an effort to reduce its photocatalytic effects. This review provides an overview of the potential risks arising from and opportunities presented by the use of TiO2 in skin care formulations.

Dispensing of minitablets - Has the problem been resolved?

Recently, minitablets have been given extensive coverage in literature, as they are perfectly matched to the current therapy individualization trend. Within this scope, special attention is paid to minitablets that enable convenient drug intake for patients with swallowing problem. However, the packaging system, dispensing the necessary amount of drug units and safe administration still remain unsolved problems or are partially overlooked. Although there are many different approaches towards dosing tablets, only a few seem to be tailored to particularly small tablets. Moreover, none of these approaches meets all the user's expectations. This paper comprehensively elaborates and critically discusses the available dosing options like sachets, blisters, home electronic dispensing systems and minitablets manual dispensers. Additional tests have been also conducted to simulate the handling and dosing procedure with 2 mm diameter placebo minitablets. Despite many advantageous inventions, it has been revealed that further efforts are necessary to identify the optimal design that would allow to eliminate the shaking procedure, adjust cavities diameter or provide better protection against humidity. Nevertheless, the current trend may lead to individual therapy becoming more convenient, safe and reliable, especially in pediatric and geriatric patients.

Implementing the Design of Experiments (DoE) Concept into the Development Phase of Orodispersible Minitablets (ODMTs) Containing Melatonin.

Development of orodispersible minitablets (ODMTs) requires consideration of aspects related to small dimensions, while ensuring short disintegration time with sufficient mechanical stability. In order to meet these and other critical quality attributes (CQAs), quality by design is encouraged. According to this approach, formulation and compression process factors were systematically studied using design of experiments (Plackett-Burman for screening purposes, full and fractional factorial design for in-depth characterization) to understand their influence on CQAs of orodispersible minitablets containing melatonin. Mathematical models describing the relationships between processing variables and attributes such as resistance to crushing and disintegration time were successfully developed, characterized by high coefficients of determination (R2adj = 0.90-0.97) and prediction errors in the range (+2.4 to -10.8%). In conclusion, based on these models, the design space was created for melatonin ODMTs, ensuring the product's quality and process robustness. Moreover, the study demonstrated the suitability of texture analysis as an alternative to compendial measurement methods of resistance to crushing and disintegration time. Graphical abstract.

A Systematic Approach to the Development of Cilostazol Nanosuspension by Liquid Antisolvent Precipitation (LASP) and Its Combination with Ultrasound.

Nanosizing is an approach to improve the dissolution rate of poorly soluble drugs. The first aim of this work was to develop nanosuspension of cilostazol with liquid antisolvent precipitation (LASP) and its combination with ultrasound. Second, to systematically study the effect of bottom-up processing factors on precipitated particles' size and identify the optimal settings for the best reduction. After solvent and stabilizer screening, in-depth process characterization and optimization was performed using Design of Experiments. The work discusses the influence of critical factors found with statistical analysis: feed concentration, stabilizer amount, stirring speed and ultrasound energy governed by time and amplitude. LASP alone only generated particle size of a few microns, but combination with ultrasound was successful in nanosizing (d10 = 0.06, d50 = 0.33, d90 = 1.45 µm). Micro- and nanosuspension's stability, particle morphology and solid state were studied. Nanosuspension displayed higher apparent solubility than equilibrium and superior dissolution rate over coarse cilostazol and microsuspension. A bottom-up method of precipitation-sonication was demonstrated to be a successful approach to improve the dissolution characteristics of poorly soluble, BCS class II drug cilostazol by reducing its particle size below micron scale, while retaining nanosuspension stability and unchanged crystalline form.

Physiologically Based Dissolution Testing in a Drug Development Process-a Case Study of a Successful Application in a Bioequivalence Study of Trazodone ER Formulations Under Fed Conditions.

Development of generic extended-release (ER) formulations is challenging. Especially under fed conditions, the risk of failure in bioequivalence trials is high because of long gastric residence times and susceptibility to food effects. We describe the development of a generic trazodone ER formulation that was aided with a biorelevant dissolution evaluation. Trazodone hydrochloride 300-mg monolithic matrix tablets were dissolved both in USP and EMA compliant conditions and in the StressTest device that simulated both physicochemical and mechanical conditions of the gastrointestinal passage. The final formulation was tested against the originator, Trittico XR 300 mg, in a randomized cross-over bioequivalence trial with 44 healthy volunteers, in agreement with EMA guidelines. Initially developed formulations dissolved trazodone similarly to the originator under standard conditions (f2 factor above 50), but their dissolution kinetics differed significantly in the biorelevant tests. The formulation was optimized by the addition of low-viscosity hypromellose and mannitol. The final formulation was approved for the bioequivalence trial. Calculated Cmax were 1.92 ± 0.77 and 1.92 ± 0.63 [µg/mL], AUC0-t were 27.46 ± 8.39 and 29.96 ± 9.09 [µg∙h/mL], and AUC0-∞ were 28.22 ± 8.91 and 30.82 ± 9.41 [µg∙h/mL] for the originator and test formulations, respectively. The 90% confidence intervals of all primary pharmacokinetic parameters fell within the 80-125% range. In summary, biorelevant dissolution tests supported successful development of a generic trazodone ER formulation pharmaceutically equivalent with the originator under fed conditions. Employment of biorelevant dissolution tests may decrease the risk of failure in bioequivalence trials of ER formulations.

Biorelevant In Vitro Release Testing and In Vivo Study of Extended-Release Niacin Hydrophilic Matrix Tablets.

Niacin (nicotinic acid, NA) is administered orally as an antihyperlipidemic agent in extended-release (ER) tablets in high doses. Due to rapid absorption and extensive metabolism (non-linear pharmacokinetics), the drug plasma levels are highly variable, which may correlate with side effects. Interestingly, this erratic drug delivery behavior of niacin ER products cannot be clarified by compendial in vitro release testing. The standard dissolution tests do not allow to mimic the selected GI tract characteristics in order to estimate the robustness of formulation under the variability of the physiological conditions. These are characterized by the pH value, impact of motility forces and composition, as well as volume of GI liquids. Our paper demonstrates a comparison of a newly developed ER HPMC niacin formulation with an originator product. The research aimed to design a robust matrix tablet of comparable biopharmaceutical behavior, safety and efficacy. The extensive in vitro investigation, including dynamic studies in flow-through cell apparatus and stress test device, forms the basis for the evaluation of nicotinic acid plasma concentrations in vivo. The occurrence of erratic, multiple NA plasma peaks after the administration of both extended-release products is a result of its local input excess over the metabolic threshold (at the level corresponding to maximum 2% of the administered dose, i.e., 20 mg of drug) due to the mechanical stresses of physiological intensity. We demonstrate how this behavior is similar for both marketed and test products. In this context, we describe how a robust ER matrix and well-designed formulation does not guarantee the test product's bioequivalence to the comparator one out of reasons unrelated to technology and biopharmaceutical properties, but because of the active compound's intrinsic pharmacokinetic characteristics, i.e., highly variable, extensive metabolism of nicotinic acid.

Drug Delivery Systems for Vitamin D Supplementation and Therapy.

Vitamin D (VD) is a fat-soluble prohormone well known for its role in regulating calcium and phosphate metabolism. It has been clinically used for many years to prevent rickets in children, osteomalacia, and osteoporosis in adults. VD insufficiency is a common medical condition, and many supplements are available in the market in order to increase serum 25-hydroxy VD levels to recommended amounts. Over the course of the last decades, it has become increasingly clear that calcitriol, an active form of VD, regulates multiple cellular processes with effects on normal and malignant cell growth and differentiation, and on the immune and cardiovascular function. Increasing evidence supports the role of the VD system in cancer prevention and therapy. Due to many pleiotropic and beneficial effects in extra-skeletal disorders, VD has gained potential and become an interesting active for encapsulation into drug delivery systems. The purpose of this review is to present the diversity of drug delivery systems that have been reported for VD or VD derivatives in an orderly manner across the following categories: Oral administration, application on the skin, cancer prevention/therapy, and other diseases or routes of administration.

Modifying release of poorly soluble active pharmaceutical ingredients with the amine functionalized SBA-16 type mesoporous materials.

SBA-16 and two modified SBA-16 type ordered mesoporous silica were used as the carriers for ibuprofen (anti-inflammatory drug) and furosemide (loop diuretic drug). Modification of the solid carrier was prepared with chitosan or N-3[(amino(poly-propylenoxy)]aminopropyltrimethoxysilane. The samples of carriers and carrier-drug loaded materials were characterized by X-ray diffraction, N2 adsorption, Fourier-transform infrared spectroscopy, thermogravimetry, and differential scanning calorimetry. The release profiles of active pharmaceutical ingredients were performed in media with different pH in the USP 2 apparatus as well as in two biorelevant media (fasted state simulated gastric fluid and fasted state small intestinal fluid) in USP 4 apparatus. The loading of active substances into mesoporous materials was performed with modified immersion method. The maximum content of deposited drug in mesoporous material was close to 12.0 and 2.2 wt.% for ibuprofen and furosemide, respectively. After drug adsorption, the reduction of BET surface area, pore volume and pore diameter of non-modified and modified SBA-16 was observed, while the cubic arrays of siliceous matrix were well preserved. The release profiles of ibuprofen and furosemide loaded in mesoporous materials in media with different pH and biorelevant fasted state simulated gastric fluid and fasted state small intestinal fluid showed that the new SBA-16 type materials modify the release profiles of furosemide, increasing the dissolution rate of these substances in the medium at pH 1.2. The cytotoxicity of the materials and permeability of drugs after their loading on SBA-16 materials were evaluated on Caco-2 model. The results of our study showed that mesoporous materials did not exert cytotoxic effects and did not influence on the permeability of both active pharmaceutical ingredients in relation to pure substances.

Cilostazol-loaded electrospun three-dimensional systems for potential cardiovascular application: Effect of fibers hydrophilization on drug release, and cytocompatibility.

Currently marketed drug-eluting stents are non-selective in their anti-restenotic action. New active substance introduction to polymeric stents and vascular grafts can promote early re-endothelialization, crucial in preventing implant restenosis. Additionally, managing material hydrophobicity by blending synthetic polymers limits adverse effects on bulk properties and controls active substance release. However, the influence of hydrophilic synthetic polymer on human cells in the cardiovascular system remains to be determined. In this report, effects of both poly(ε-caprolactone) (PCL) fibers hydrophilization with Pluronic P123 (P123) and cilostazol (CIL) loading were studied. Physicochemical and mechanical properties of electrospun tubular structures produced from PCL and PCL/P123 fibers with and without CIL were investigated and compared. Release profiles studies and in vitro cell proliferation assays of electrospun materials were conducted. It was found that P123 located near the surface of electrospun fibers increased the rate of CIL release. PCL formulation sustained human umbilical vein endothelial cells (HUVEC) growth for 48 h. Despite improved hydrophilicity, PCL/P123 formulations were found to reduce HUVEC viability. Both PCL and PCL/P123 materials reduced primary aortic smooth muscle cells (PASM) viability after 48 h. In PCL formulations containing CIL, drug release caused a decrease in PASM viability. P123 blending with PCL was found to be as a useful pre-fabrication technique for modulating surface hydrophobicity of electrospun materials and the release profile of incorporated active substance. The cytotoxicity of P123 was evaluated to improve the design of drug-loaded vascular grafts for cardiovascular applications.

Cilostazol-Loaded Poly(ε-Caprolactone) Electrospun Drug Delivery System for Cardiovascular Applications.

PURPOSE: The study discusses the value of electrospun cilostazol-loaded (CIL) polymer structures for potential vascular implant applications. METHODS: Biodegradable polycaprolactone (PCL) fibers were produced by electrospinning on a rotating drum collector. Three different concentrations of CIL: 6.25%, 12.50% and 18.75% based on the amount of polymer, were incorporated into the fibers. The fibers were characterized by their size, shape and orientation. Materials characterization was carried out by Fourier Transformed Infrared spectroscopy (FTIR), Raman spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD). In vitro drug release study was conducted using flow-through cell apparatus (USP 4). RESULTS: Three-dimensional structures characterized by fibers diameter ranging from 0.81 to 2.48 µm were in the range required for cardiovascular application. DSC and XRD confirmed the presence of CIL in the electrospun fibers. FTIR and Raman spectra confirmed CIL polymorphic form. Elastic modulus values for PCL and the CIL-loaded PCL fibers were in the range from 0.6 to 1.1 GPa. The in vitro release studies were conducted and revealed drug dissolution in combination with diffusion and polymer relaxation as mechanisms for CIL release from the polymer matrix. CONCLUSIONS: The release profile of CIL and nanomechanical properties of all formulations of PCL fibers demonstrate that the cilostazol loaded PCL fibers are an efficient delivery system for vascular implant application.

Implementation of quality by design approach in manufacturing process optimization of dry granulated, immediate release, coated tablets - a case study.

The aim of this study was to optimize the process of tablets compression and identification of film-coating critical process parameters (CPPs) affecting critical quality attributes (CQAs) using quality by design (QbD) approach. Design of experiment (DOE) and regression methods were employed to investigate hardness, disintegration time, and thickness of uncoated tablets depending on slugging and tableting compression force (CPPs). Plackett-Burman experimental design was applied to identify critical coating process parameters among selected ones that is: drying and preheating time, atomization air pressure, spray rate, air volume, inlet air temperature, and drum pressure that may influence the hardness and disintegration time of coated tablets. As a result of the research, design space was established to facilitate an in-depth understanding of existing relationship between CPPs and CQAs of intermediate product (uncoated tablets). Screening revealed that spray rate and inlet air temperature are two most important factors that affect the hardness of coated tablets. Simultaneously, none of the tested coating factors have influence on disintegration time. The observation was confirmed by conducting film coating of pilot size batches.

STUDY OF OFLOXACIN ENANTIOMERS DISSOLUTION FROM SELECTED SOLID DOSAGE FORMS USING HIGH PERFORMANCE CAPILLARY ELECTROPHORESIS METHOD.

The commercially available coated tablets containing either racemic form of ofloxacin (Tarivid 200 mg, OfloHexal 200 mg and Ofloxacin-Ratiopharm 200 mg) or only levofloxacin S-(-)-isomer (Tavanic 250 mg) were examined. The aim of our study was to establish the kinetics of dissolution rate process of ofloxacin optical isomers (S-(-) and R-(+)-ofloxacin) from solid oral dosage forms using flow-through cell method (USP 4 method). The concentrations of analytes (racemic ofloxacin and its enantiomers) in the samples of tablet extracts as well as in dissolution media (0.1 M/L HCl and phosphate buffer pH 6.8) were determined by validated high performance capillary electrophoresis method. The fraction of the average dose of the individual optical isomers of ofloxacin released from the examined tablets was calculated. In the case of the OfloHexal, Ofloxacin-Ratiopharm and Tavanic it was found to be around 100% for both S-(-) and R-(+)-ofloxacin in 0.1 M/L HCI after 30 min of dissolution test. The fraction of the average dose for the Tarivid tablets was approximately 50% at the same time. A similar results were observed for the Ofloxacin-Ratiopharm and Tavanic tablets examined in phosphate buffer (average fraction about 100% after 30 min), while in the case of Tarivid and OfloHexal the averige fraction of the dose determined in a buffer pH 6.8 was 14% and 44%, respectively. There were not found any differences in the kinetics of dissolution of the S-(-)-ofloxacin and R-(+)-ofloxacin isomers within the same formulation. However, statistically significant differences were found in the dissolution of ofloxacin enantiomers between different preparations.

The influence of direct compression powder blend transfer method from the container to the tablet press on product critical quality attributes: a case study.

OBJECTIVE: The aim of this article is to compare the gravitational powder blend loading method to the tablet press and manual loading in terms of their influence on tablets' critical quality attributes (CQA). SIGNIFICANCE: The results of the study can be of practical relevance to the pharmaceutical industry in the area of direct compression of low-dose formulations, which could be prone to content uniformity (CU) issues. METHODS: In the preliminary study, particle size distribution (PSD) and surface energy of raw materials were determined using laser diffraction method and inverse gas chromatography, respectively. For trials purpose, a formulation containing two pharmaceutical ingredients (APIs) was used. Tablet samples were collected during the compression progress to analyze their CQAs, namely assay and CU. RESULTS: Results obtained during trials indicate that tested direct compression powder blend is sensitive to applied powder handling method. Mild increase in both APIs content was observed during manual scooping. Gravitational approach (based on discharge into the drum) resulted in a decrease in CU, which is connected to a more pronounced assay increase at the end of tableting than in the case of manual loading. CONCLUSIONS: The correct design of blend transfer over single unit processes is an important issue and should be investigated during the development phase since it may influence the final product CQAs. The manual scooping method, although simplistic, can be a temporary solution to improve the results of API's content and uniformity when compared to industrial gravitational transfer.

S-Nitrosothiols-NO donors regulating cardiovascular cell proliferation: Insight into intracellular pathway alterations.

Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) activates signaling pathways responsible for smooth muscle cell relaxation, leading to vasodilation and thus plays an important role in controlling vascular homeostasis, thrombosis and inflammation. Recent studies indicate that S-nitrosothiols produced in vivo as well as synthetic ones might be important reservoirs of NO. Based on a broad range of NO functions within the living organisms, this review highlights the impact of S-nitrosothiols on cardiovascular cell cycle. The cell membrane transport and the decomposition patterns responsible of S-nitrosothiols actions are presented. The effects of NO delivery through S-nitrosothiols have a significant potential in cardiovascular diseases with various underlying causes. The challenges related to their application in the pharmacotherapy of patients with various cardiovascular diseases are also discussed.

DISSOLUTION KINETICS STUDIES OF CLOPIDOGREL FROM SELECTED MULTISOURCE COATED TABLETS WITH APPLICATION OF CAPILLARY ZONE ELECTROPHORESIS METHOD.

Resistance to an anti-platelet agent clopidogrel (CLP) and the growing number of products with the drug cause the need for comparison of their quality to assure patients safe and effective treatment. Therefore, the aim of the study was to compare in vitro dissolution kinetics of CLP immediate-release tablets, commonly used in anti-platelet therapy in Poland. For analysis of CLP in samples obtained from dissolution test a capillary zone electrophoresis (CZE) method was elaborated and validated. Separation of CLP and ticlopidine, used as an internal standard, was performed in silica capillary filled with phosphate buffer of pH 2.5, at the applied voltage of 20 kV. The CZE method fulfilled the validation requirements for determination of drugs in pharmaceutical matrices and was successfully applied for analysis of CLP dissolved from the tablets. Dissolution profiles were prepared for each product and mean dose fractions of CLP dissolved from tablets at 30 min were calculated. Kinetic parameters of the CLP dissolution from the studied products were compared. Analysis of variance (ANOVA) did not reveal differences between CLP fractions dissolved at 30 min time point from the tested drug products. However, ANOVA with Tukey multiple comparison test revealed significant differences in first-order dissolution rate constants and t0.5 values (times at which 50% of drug is dissolved) of CLP among tested tablets. It was concluded that the studied CLP products met the acceptance criteria regarding dissolution test but differed with each other in dissolution kinetics.

Evaluation of drug-carrier interactions in quaternary powder mixtures containing perindopril tert-butylamine and indapamide.

Interactions occurring between components in the quaternary powder mixtures consisting of perindopril tert-butylamine, indapamide (active pharmaceutical ingredients), carrier substance and hydrophobic colloidal silica were examined. Two grades of lactose monohydrate: Spherolac(®) 100 and Granulac(®) 200 and two types of microcrystalline cellulose: M101D+ and Vivapur(®) 102 were used as carriers. We determined the size distribution (laser diffraction method), morphology (scanning electron microscopy) and a specific surface area of the powder particles (by nitrogen adsorption-desorption). For the determination of the surface energy of powder mixtures the method of inverse gas chromatography was applied. Investigated mixtures were characterized by surface parameters (dispersive component of surface energy, specific interactions parameters, specific surface area), work of adhesion and cohesion as well as Flory-Huggins parameter χ23('). Results obtained for all quaternary powder mixtures indicate existence of interactions between components. The strongest interactions occur for both blends with different types of microcrystalline cellulose (PM-1 and PM-4) while much weaker ones for powder mixtures with various types of lactose (PM-2 and PM-3).

Recent progress in continuous and semi-continuous processing of solid oral dosage forms: a review.

CONTEXT: Continuous processing is an innovative production concept well known and successfully used in other industries for many years. The modern pharmaceutical industry is facing the challenge of transition from a traditional manufacturing approach based on batch-wise production to a continuous manufacturing model. OBJECTIVE: The aim of this article is to present technological progress in manufacturing based on continuous and semi-continuous processing of the solid oral dosage forms. METHODS: Single unit processes possessing an alternative processing pathway to batch-wise technology or, with some modification, an altered approach that may run continuously, and are thus able to seamlessly switch to continuous manufacturing are briefly presented. Furthermore, the concept of semi-continuous processing is discussed. Subsequently, more sophisticated production systems created by coupling single unit processes and comprising all the steps of production, from powder to final dosage form, were reviewed. Finally, attempts of end-to-end production approach, meaning the linking of continuous synthesis of API from intermediates with the production of final dosage form, are described. RESULTS: There are a growing number of scientific articles showing an increasing interest in changing the approach to the production of pharmaceuticals in recent years. Numerous scientific publications are a source of information on the progress of knowledge and achievements of continuous processing. These works often deal with issues of how to modify or replace the unit processes in order to enable seamlessly switching them into continuous processing. A growing number of research papers concentrate on integrated continuous manufacturing lines in which the production concept of "from powder to tablet" is realized. Four main domains are under investigation: influence of process parameters on intermediates or final dosage forms properties, implementation of process analytical tools, control-managing system responsible for keeping continuous materials flow through the whole manufacturing process and the development of new computational methods to assess or simulate these new manufacturing techniques. The attempt to connect the primary and secondary production steps proves that development of continuously operating lines is possible. CONCLUSION: A mind-set change is needed to be able to face, and fully assess, the advantages and disadvantages of switching from batch to continuous mode production.

Nitric oxide-eluting scaffolds and their interaction with smooth muscle cells in vitro.

Fabrication of scaffolds loaded with nitric oxide (NO) donors (S-nitrosoglutathione, GSNO, and isosorbide mononitrate, ISMN) with suitable cell compatibility and optimized properties for tissue-engineering applications is reported using "in situ" technique. Based on FDA-approved polymer, solvent and dosage forms, this gentle process allowed the incorporation of the GSNO labile drug into scaffolds made of either poly(lactide-co-glycolide) (PLGA) or PLGA/poly(ɛ-caprolactone) (PCL) blend. During scaffolds manufacturing process including washing cycles, NO donors were leached from scaffolds. However, GSNO and ISMN concentrations in the last washing medium (10(-7) M and 10(-4) M, respectively) were in the range of cell suitability for tissue engineering. Further morphological analyses indicated that smoother surfaces with fewer but bigger pores (compatible with cell penetration and ingrowth) were obtained with PLGA in comparison with PLGA/PCL scaffolds. Among all tested matrices, only unloaded PLGA and GSNO-loaded PLGA/PCL exhibited intermediate cell anchorage, with mitochondrial activity close to the control and an increase in protein content, a prognostic for scaffold cell colonization, defining them as promising candidates. Deeper analyses of these two scaffolds looking at intracellular redox balance through reactive oxygen species production, glutathione, S-nitrosothiols, and nitrite ions content exhibited GSNO-loaded PLGA/PCL as the best of all tested 3D scaffolds for tissue engineering.

Characterization of new eye drops with choline salicylate and assessment of their irritancy by in vitro short time exposure tests.

The aim of our study was to examine the irritation potential of new eye drops containing 2% choline salicylate (CS) as an active pharmaceutical ingredient (API) and various polymers increasing eye drop viscosity (hydroxyethylcellulose, hydroxypropyl methylcellulose, methylcellulose, polyvinyl alcohol, polyvinylpyrrolidone). The standard method for assessing the potential of irritating substances has been the Draize rabbit eye test. However the European Centre for Validation of Alternative Methods and the Coordinating Committee for Validation of Alternative Methods recommend, short time exposure (STE) in vitro tests as an alternative method for assessing eye irritation. The eye irritation potential was determined using cytotoxicity test methods for rabbit corneal cell line (SIRC) after 5 min exposure. The viability of cells was determined using two cytotoxicity assays: MTT and Neutral Red Uptake. According to the irritation rankings for the short time exposure test, all tested eye drops are classified as non-irritating (cell viability >70%).