Tablet Surface Research Articles

A Study on The Formulation of Plant Matrix Tablets From Coarse Botanical Materials Using Cinnamon Bark and Areca Nut as The Model Botanical Materials

Background: There is much interest in formulating botanical materials into tablets due to the compactness and ease of administration. However, tableting of coarse milled botanical materials poses a challenge due to poor tableting properties. Objective: To evaluate the feasibility of wet granulation to produce tablets from coarse milled botanical materials and to assess the effect of formulation on properties of the tablets. Materials and Methods: Cinnamon bark and areca nut were milled to obtain 1–2 mm particle size, which was subsequently used in wet granulation using maltodextrin solution as a granulating liquid. Two diluents were tried; microcrystalline cellulose (MCC) or mannitol at a different ratio to the botanical materials. Tablets were then produced from the granules and evaluated for tensile strength and surface roughness. Results: Tablets formulated with MCC had higher tensile strength than tablets formulated with mannitol. Additionally, granules prepared using mannitol were more friable than those with MCC. The effect of diluent to botanical material ratio was more prominently observed on tablet surface roughness. Tablets containing a higher ratio of botanical material had a rougher surface, which could have implications on the mouth-feel of the tablets. Conclusion: Wet granulation could be a viable pre-processing method to produce tablets from coarse milled botanical materials.

Establishment of a Novel Method to Evaluate Water Permeation Rates by Combining the Dynamic Contact Angle and Thermographic Approach: Significance of Disintegration Properties of Orally Disintegrating Tablets

The purpose of the present study was to establish a novel method to evaluate water penetration rates by combining the local dynamic contact angle and thermographic approach to characterize water conduction properties in orally disintegrating (OD) tablets. The OD tablet tester OD-mate was used to measure the disintegration times of OD tablets. Other formulation characteristics, such as tablet hardness and friability, were evaluated. By examining three formulation characteristics, such as the disintegration time, tablet hardness, and friability, of 33 OD tablets for generic drugs, four characteristic OD tablets containing aripiprazole were selected. To quantitatively evaluate water penetration rates into the tablet interior, we measured the dynamic contact angle after dropping water locally on the tablet surface. Linearity with a high correlation coefficient was observed for each of the initial time-dependent changes in the dynamic contact angle. Water penetration rates into tablets were approximately twice as fast for Pharmaceuticals A and B than for Pharmaceuticals C and D. These rates were consistent with changes observed in tablet thermographic imaging. The relationship between the rapid disintegration of the tablet and its physical strength was discussed based on the internal structure of the tablet by X-ray CT and the additives of each OD tablet. The present results demonstrated that the water penetration rates of OD tablets, as measured by dynamic contact angle, may accurately detect differences in disintegration times in the human oral cavity.

Influential factors and spatial suitability of the method of limestone tablets in karst carbon cycle study in China

As an intuitive way, the method of limestone tablets (MLT) is often used in dissolution rate calculation and carbon cycle research of carbonate rocks. To clarify the influential factors and spatial suitability of MLT in karst carbon cycle study, 30 MLT test sites in China from north to south were collected and the tablets’ dissolution rate (TDR) was analyzed. The results showed that the influence of precipitation on the TDR is more significant than that of the temperature, especially in the impact on the underground tablets. Three typical river basins, i.e., the Nanchuan River karst basin of northern China (NKB), Qingliangsigou loess basin of northern China (QLB), and Wujiang River karst basin of southern China (WKB) were collected as the key research areas to reveal the regional factors of lithology, soil physical–chemical properties, and land use that affect TDR. The results show that the higher the acid insolubility of rocks, the lower is the dissolution rate. Soil CO2 displayed a positive correlation with TDR in both the northern and southern karst areas of China. Because soil inorganic carbon (SIC) always causes carbon deposits on the tablet surface which made the calculated results of carbon sink inaccurate, the MLT is not suitable for carbon cycle research in the loess area where high SIC is contained. The hydrochemical runoff method may be better selected. In the arid and semi-arid karst basin of northwestern and northern China, the high SIC area should be avoided during carbon sink study with MLT.

Rapid detection of sulfonamides by heat assisted desorption-dielectric barrier discharge ionization mass spectrometry

Sulfanilamide is a common antibacterial drug that is used in clinical practice and in the industry. However, its abuse has emerged as a serious problem in the aquaculture industry, and more predominantly in the poultry industry, where it is administered for therapeutic purposes or as a growth promoter. In this study, a novel technical platform, heat-assisted desorption-dielectric barrier discharge ionization mass spectrometry (HAD-DBDI-MS), was used to detect sulfanilamide in situ. A method for the rapid identification of five typical sulfanilamide drugs sulfamopyridine, sulfamethoxan, sulfamethoxoline, sulfamidine, and sulfamethoxazole was established after optimizing a series of parameters. Secondary mass spectrometry was used to distinguish the sulfanilamide drugs from one another and from other isomers. Our HAD-DBDI-MS method enhanced the sulfanilamide sensitivities by reducing the limits of detection by about 1-2 orders of magnitude compared to those obtained with the DBDI-MS method. As further research, the profiles of chicken feed with added sulfamopyridine standard as well those of commercial feed with added sulfamidine and sulfamethoxazole were obtained using HAD-DBDI-MS respectively. With the HAD-DBDI-MS method, sulfamopyridine could be directly detected in the complex chicken meat matrix. However, satisfactory results were not obtained when direct HAD-DBDI-MS was used for sulfamidine and sulfamethoxazole detection in the feed matrix. The identification ability was improved when methanol was introduced as the assisting solvent. In this method, chicken feed spiked with sulfamidine and sulfamethoxazole standards were pressed into tablets, and methanol was dropped on the tablet surface. The experimental data indicate that HAD-DBDI-MS is suitable for the rapid identification of sulfanilamide drugs in poultry feed and meat products, thus showing potential value as a detection tool for future application.

Development of an appropriate simple suspension method for valganciclovir medication

BackgroundValganciclovir (VGC) is essential for preventing cytomegalovirus infections after transplants in adult and pediatric patients. In pediatric patients, VGC tablets have to be pulverized so that they can be delivered via nasogastric tubes. The “simple suspension method” is usually used to suspend tablets in hot water in Japan. However, the optimal suspension conditions and metering methods for preparing VGC suspensions using the simple suspension method are unclear. The purpose of this study was to clarify these issues.MethodsVGC tablets were suspended in water (initial water temperature: 25 °C or 55 °C) using the simple suspension method. The residual rate of VGC after it had been suspended in hot water was determined using HPLC. In addition, the suspended solution was passed through 6, 8, and 12 Fr. gavage tubes. The VGC concentrations of suspensions produced using different preparation methods were also determined using HPLC.ResultsCracking the surfaces of VGC tablets and suspending them in water at an initial temperature of 55 °C was effective at dissolving the tablets. The VGC concentration of the suspension remained stable for at least 80 min. Furthermore, the VGC concentration remained stable for 48 h during cold dark storage. Cracking the surfaces of VGC tablets could be a more effective metering method than preparing powder from VGC tablets. In addition, little VGC remained in 6, 8, or 12 Fr. gavage tubes after VGC solution was passed through them.ConclusionThe amount of VGC should be measured carefully when preparing VGC solutions using the simple suspension method.

Quality by design (QbD) approach to match tablet glossiness

A quality by design (QbD) approach was used for a polyvinyl alcohol (PVA)-based coating to develop a ‘look-alike’ placebo tablet, which can match the glossiness (shine) of an innovator tablet. Critical coating parameters such as exhaust temperature, drying capacity, solid concentration in coating dispersion, and plasticizer concentration were studied using a full factorial design of experiment (DoE). Total of 20 experimental coating runs was executed on a pilot scale using a perforated pan coater. Coated tablets were evaluated visually against the innovator product by a panel of 13 volunteers using an individual questionnaire about the tablet appearance. The tablet appearance included factors such as tablet surface shine, surface roughness, and logo bridging. These data were analyzed using JMP software. Solid concentration in coating dispersion and drying capacity were found to be the key contributing parameters for tablet surface shine. Human observations were more discerning in spotting subtle differences in tablet appearance than Munsell evaluation. By the judicious selection of a solid concentration in coating dispersion and drying conditions, a look-alike placebo tablet was successfully developed. Change in tablet shape or size did not affect the tablet shine. However, replacement of PVA-based coating with hydroxypropyl methylcellulose (HPMC)-based coating resulted in reduced shine irrespective of tablet shape and size.

Analysis of available surface area can predict the long-term dissolution profile of tablets using short-term stability studies.

Generally, since at least 6months are usually needed for accelerated testing of tablet at 40°C/75% relative humidity (RH), it would be crucial important to predict the dissolution profiles during long-term storage period by using samples stored with shorter periods such as 3months. In this study, we developed a new method for predicting changes in dissolution from tablets during long-term storage-based changes in the available surface area [S (t)]. In addition, we discussed the dissolution behavior and mechanisms using S (t). The results revealed drastic delays in dissolution in samples stored at 40°C/75% RH for 7weeks. Considering changes of S (t) patterns, this delay was derived from changes of the tablet surface. New parameters, namely T22.1 and T63.2, calculated from the S (t) profile tended to increase with an increased duration of testing. Concerning the long-term prediction model using short-term data, a nonlinear model was deemed appropriate because good agreement was observed between the value predicted using the model and the measured value for samples stored at 40°C/75% RH for 6months. Therefore, using the new evaluation method based on S (t), we can predict changes in dissolution during long-term storage using short-term methods.

Dynamic structure model of polyelectrolyte complex based controlled-release matrix tablets visualized by synchrotron radiation micro-computed tomography.

Hydrophilic matrix tablets are the most commonly used dosage forms to fabricate oral controlled-release systems. It is highly desirable to design delivery system with novel mechanism to achieve sustained drug release through a simplified preparation process. The chitosan-anionic polymers based matrix tablets is assumed to produce self-assembly in the gastrointestinal tract, then transferring into film-coated tablets from original matrix type. But its dynamic behavior during dissolution process and the on-going internal microstructural changes during drug release were still in the dark. In this study, by using synchrotron radiation X-ray micro-tomography (SR-μCT) with phase contrast imaging, the micro-structure characteristics of chitosan-λ-carrageenan (CS-λ-CG) matrix based tablets during the dissolution were successfully elucidated for the first time. The qualitative and quantitative analyses of intensity distribution distinguished a hydrated CS-λ-CG layer from a solid core. Visualization based on 3D models provided quantitative details on the micro-structural characteristics of hydration dynamics. After CS-λ-CG matrix tablets were immersed in simulated gastric fluid (SGF) pH1.2 medium for 0.5-2.0h, the hydrated layer transformed into a gel layer and a solid swollen layer. The erosion front, swelling front, and solvent penetration front were also defined from the distinguishable micro-structures. More importantly, once the matrix tablet was transferred from SGF to the simulated intestinal fluid (SIF) pH6.8 medium, a new layer with the enhanced strength and compactness in comparison to common gels was formed on the surface of tablets. The temporal and spatial variation of 3D models further provided direct evidence for this cross-linking behavior, the new layer was composed of CS-λ-CG polyelectrolyte complexes (PEC) which subsequently dominated release mechanisms. In summary, the phase contrast SR-μCT technique was utilized to investigate the hydration dynamics of CS-λ-CG matrix tablets which was supposed to provide a novel drug release mechanism. Based on the structure feature obtained from the high contrast image, different hydration region was distinguished and the cross-linked film was identified and visualized directly for the first time.

Formulation design for inkjet-based 3D printed tablets

The drug loading efficiency was evaluated using a binder-jet 3D printing process by incorporating an active pharmaceutical ingredient (API) in ink, and quantifying the printability property of ink solutions. A dimensionless parameter Ohnesorge was calculated to understand the printability property of the ink solutions. A pre-formulation study was also carried out for the raw materials and printed tablets using thermal analysis and compendial tests. The compendial characterization of the printed tablets was evaluated with respect to weight variation, hardness, disintegration, and size; Amitriptyline Hydrochloride was considered as the model API in this study. Four concentrations of the API ink solutions (5, 10, 20, 40mg/mL) were used to print four printed tablet batches using the same tablet design file. The excipient mixture used in the study was kept the same and consists of Lactose monohydrate, Polyvinyl pyrrolidone K30, and Di-Calcium phosphate Anhydrate. The minimum drug loading achieved was 30μg with a minimal variation (RSD) of <0.26%. The distribution of the API on the tablet surface and throughout the printed tablets were observed using SEM-EDS. In contrast, the micro-CT images of the printed tablets indicated the porous surface structure of the tablets. The immediate release properties of the printed tablets were determined using a dissolution study in a modified USP apparatus II.

Partial tablet coating by 3D printing.

In the last decade 3D printing (3DP) technology has gained increasing interest in the pharmaceutical field addressing several novel challenges such as on-demand manufacturing at the point of need, customization of drug release profiles and patient-specific solutions as well as combinations of several APIs in one dosage form. Therefore, 3DP can become a new and promising path to drug product development and manufacturing, able to support specific therapies and improve compliance, safety and effectiveness. The aim of this work was to partially coat tablets with a glyceride, namely Precirol ATO 5 using a semi-solids 3D printer as an approach for tuning the release of two Active Pharmaceutical Ingredients (APIs), the hydrophilic methyl-levodopa hydrochloride (Melevodopa) and the lipophilic Acyclovir. Various parameters of the 3DP coating process were purposefully modified using experimental design techniques in order to customize the selected APIs release profile, without affecting the core composition of the formulation. The percentage of the tablet surface coated, the number of coating layers as well as the coated sides of the tablet where the parameters which controlled the release profile for both APIs. Different dissolution profiles have been achieved by tuning these simple parameters, which revealed a non-Fickian release mechanism regardless of the API.

Influence of ambient-tablet PC luminance ratio on legibility and visual fatigue during long-term reading in low lighting environment

We examine the effect of the (luminance) ratio of ambient luminance to tablet surface luminance on text legibility and fatigue over 1 h of long-term reading with a tablet PC in low-ambient-luminance environments limited to 45 cd/m2 (illuminance ~230 lx). Four reading-pattern subject experiments are carried out at ambient-luminance-to-tablet-surface-luminance ratios of 1:1, 1:3, 1:6, and 1:9 at 15 and 45 cd/m2. As per legibility tests based on the semantic differential (SD) method, we find that subjects experience glare at luminance ratios of 1:6 and 1:9, and it is difficult to read text at the luminance ratio of 1:9 under ambient luminances of 15 and 45 cd/m2. Based on subject fatigue (determined by subjective symptom survey), we find that the feeling of fatigue, according to the change in the luminance ratio, most affects the Fuzziness group among the five subjective fatigue groups. Based on physical fatigue determined using the critical flicker fusion frequency (CFF) value, we observe significant CFF differences before and after reading for luminance ratios of 1:1 and 1:9 at the ambient luminance of 45 cd/m2 and for the ratio of 1:9 when the ambient luminance is 15 cd/m2. A larger difference between the ambient and surface luminances corresponds to higher CFF variation rates and more fatigue.

Congruent Release of Drug and Polymer from Amorphous Solid Dispersions: Insights into the Role of Drug-Polymer Hydrogen Bonding, Surface Crystallization, and Glass Transition.

Drug loading is an important parameter known to impact the release rate of a poorly soluble drug from an amorphous solid dispersion (ASD). Recent studies have shown that small increases in drug loading can dramatically reduce the drug release rate from ASDs prepared with poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA). However, the link between drug physicochemical properties and the drug loading where the release is abruptly compromised is not well understood. This study probes the role of different factors on the relative dissolution rates of drug and polymer from PVPVA-based ASDs as a function of drug loading: (1) the impact of drug-polymer hydrogen bonding interactions on the initial dissolution rate of ASDs, investigated using two structural analogues, indomethacin (IND) and indomethacin methyl ester (INDester), (2) the influence of surface drug crystallization, observed for INDester ASDs, and (3) by changing temperature, the impact of the "wet" glass transition temperature (Tg). Scanning electron microscopy (SEM), with or without energy dispersive X-ray (EDX) analysis, Fourier transform infrared spectroscopy (FTIR), and powder X-ray diffraction (PXRD) were utilized to study the solid-state phase behavior and/or drug enrichment on the partially dissolved ASD tablet surfaces. Nanoparticle tracking analysis (NTA) was utilized to study the solution-state phase behavior. It was found that, contrary to expectations, ASDs with drug-polymer hydrogen bonding exhibited poorer initial release at moderate drug loadings (15-25%) as compared to the non-hydrogen bonding analogue ASDs. Surface crystallization led to the deterioration of dissolution performance. Lastly, Tg relative to experimental temperatures also appeared to play a role in the observed dissolution behavior as a function of drug loading. These findings shed light on potential mechanisms governing ASD dissolution performance and will aid in the development of optimized ASD formulations with enhanced dissolution performance.

Sustained release formulation of Ondansetron HCl using osmotic drug delivery approach

Ondansetron HCl (OSH) is a 5-HT3 receptor antagonist indicated for the prevention of nausea and vomiting associated with radiotherapy (adults: 8 mg, t.i.d) and/or chemotherapy (adults: 8 mg, b.i.d to t.i.d) and prevention of postoperative nausea and/or vomiting (adults: 8 mg, b.i.d). In elderly subjects, bioavailability may be somewhat higher (65%) and lower clearance, presumably due to reduced hepatic first-pass metabolism. OSH is extensively distributed in the body; about 70–75% of the drug in plasma is protein-bound and terminal elimination half-life is about 3 h after oral administration. The study was aimed to develop Push–pull Osmotic Pump (PPOP) bi-layered tablets for Ondansetron HCl ER tablets. The granulation was carried out using non-aqeous solvents followed by compression, seal coating, semi permeable coating, laser drilling (0.6 mm), and drug film coating with loading dose. The drug release was controlled by swelleable osmotic polymers of pull layer and push layer and orifice on the surface of tablet. The formulations were optimized for its core composition, extended release coating (Semipermeable membrane) polymer as to plasticizer ratio and orifice diameter. Optimized formulations were evaluated for micromeritic properties and in vitro drug release. The analytical methods were developed and validated to estimate in vitro drug potency, drug release, and in vivo pharmacokinetic parameters. Stability studies were done as per the ICH guidelines. The results of in vivo study concludes that the once OSH ER dose consistently maintains plasma concentration of drug within the therapeutic window over a period of 24 h.

Experimental study on dust reduction via spraying using surfactant solution

Spraying-based dust reduction is the main technical method to prevent and control the dust coal mines. Surfactants can improve the dust reduction effect via spraying to some extent. In this study, an experimental study was performed to investigate the physical properties of surfactant solutions in the spray and the dust-reduction efficiency of spraying. The experimental results showed that as the mass concentration of the surfactant solution increased, the surface tension decreased. When the surfactant concentration reached CMC, the surface tension of the solution would not have significant decrease any more. The surfactant had no significant effect on the dynamic viscosity of the solution. As the mass concentration of the surfactant increased, the contact angle of the droplet on the tablet surface continuously decreased. The atomization characteristics results revealed that the surfactant can promote the atomization effect and cause a small decrease in the droplet size only under the low pressure. Under the constant pressure of 0.7 MPa, the droplet size in the spraying first decreased and then increased with the increase in the concentration of the surfactant. Overall, the droplet size did not have significant change. Based on the experimental results, as the surfactant concentration increased, the dust-reduction efficiency via spraying showed a trend of first increasing and then decreasing. In addition, although the dust-reduction efficiency was improved for both the total dust and the respirable dust by the surfactant, the promotion effect for the latter was much more significant than for the former. The promotion effect of surfactants on the dust-reduction efficiency of spraying decreased with the increase of pressure.

Influence of compression at elevated temperature on the compactibility of thermo-mechanically processed polymers

Hot-melt extrusion (HME) is increasingly applied in the pharmaceutical industry for the formulation of solid dispersions of drugs with improved solubility and release. However, tableting of milled extrudates may present problems due to adverse thermo-mechanical effects on elasto-plasticity. In this work compression of hot-melt extruded polyvinyl based and polymethacrylate polymers with glass transition temperatures (Tg) up to 80 °C was performed at ambient (20 °C) and elevated (40 °C, ‘hot’ compression) temperature aiming for compactibility improvement. Polymers were characterized for morphology, particulate properties, thermal properties, microhardness and compaction behavior (‘in-die’ force-displacement data). Hot-melt extruded polymers showed lower Tg and work of compaction but higher elastic recovery and yield pressure (Kuenz-Leuenberger and Kawakita models) resulting in weak tablets. ‘In all cases, ‘hot’ compression decreased considerably the yield pressure for both unprocessed and extruded polymers indicating greater plasticity. For Eudragit® RSPO, Eudragit® L100-55 and Soluplus® with microhardness between 2.20 and 2.69 MPa it also increased consolidation due to softening of edges, thus facilitating interparticle slippage, which explained their tablet strength enhancement. Conversely, it did not affect the consolidation of Kollidon® SR with lower microhardness 0.31 and the large strength increase was attributed to the yield pressure reduction and the closeness of its Tg (42 °C) with the compression temperature increasing molecular mobility and operation of intermolecular forces. Compared to ambient compression, greater plastic deformation due to ‘hot’ compression was visible in the SEM images of tablet surfaces by the extensive formation of interparticle boundaries and by the elimination of pores. Relationships were found between yield pressure, elastic recovery, tensile strength and friability of tablets with homologous compression temperature which may be useful during formulation.

Investigation of minor elemental species within tablets using in situ depth profiling via laser-induced breakdown spectroscopy hyperspectral imaging

Laser-induced breakdown spectroscopy (LIBS) hyperspectral imaging allows for the determination of two-dimensional and three-dimensional spatial distributions of elemental species throughout complex samples. In this work, LIBS hyperspectral imaging was utilized to investigate minor elemental species within tablets. Representative LIBS spectra were initially collected on four complex, heterogeneous tablets, showing high concentrations of Ti in the tablet coating, with low and variable abundance of Na, Mg, and K. Principal component analysis revealed distinct resolution of the four tablets due to differences in Na, Mg, and K. Using two-dimensional LIBS hyperspectral imaging, spatial distributions of Na, Mg, and K within defined x and y regions of the tablet coating were generated. Subsequent three-dimensional LIBS hyperspectral imaging further elucidated the full x, y, and z spatial distributions of these minor elemental species within the tablet surface, tablet coating, and tablet core. As such, in situ depth profiling of the minor elemental species within each tablet was accomplished. Quantification of the homogeneity and uniformity of each tablet was determined. To our knowledge, this is the first report of multivariate analysis, LIBS, and LIBS hyperspectral imaging being utilized for the determination of both 2D and 3D spatial distributions of minor elemental species, along with quantification of tablet homogeneity, within tablets.

Stimuli-responsive/smart tablet formulations (under simulated physiological conditions) for oral drug delivery system based on glucuronoxylan polysaccharide

Objective: Development of stimuli-responsive intelligent drug delivery system (based on a polysaccharide, glucuronoxylan [GX]) with on-off switching properties under physiological conditions.Significance: As GX exhibits high swelling index and stimuli-responsive swelling/de-swelling properties, therefore, this material appeared highly useful to design pH, solvent and ionic stress-sensitive oral tablet formulations, which offered on-off switching properties. In this way, we could design intelligent/smart drug delivery systems for levosulpiride (LS) and theophylline (TF) with valuable pharmaceutical properties.Methods: GX-based tablet formulations were explored for stimuli-responsive, reversible swelling–deswelling behavior, dynamic swelling, and its kinetics. Tablet surface and channeling after swelling were observed using scanning electron microscopy (SEM). Drug release study was performed mimicking the physiological conditions like pH and transit time of gastrointestinal tract (GIT). Radiographic images of tablet path (in vivo) were recorded.Results: GX-based formulations exhibited high swelling in deionized water (DW), pH 6.8 and 7.4 while negligible swelling at pH 1.2. SEM images discovered the presence of microcracks and nanopores on the surface of tablets and showed channeling after swelling of tablets in DW. Sustained drug release was observed and found directly proportional to the concentration of GX in the formulations with negligible release at pH 1.2. In vivo radiographic evaluation indicated the retention of tablets in GIT for 7 h. Hemocompatibility studies showed the non-thrombogenic and non-hemolytic nature of GX.Conclusions: GX-based smart/stimuli-responsive formulations can control/sustain the release of drugs in GIT.

Effect of Moisture Absorption on Tablet Surface Structure in Magnesium Oxide Tablets

Effect of Moisture Absorption on Tablet Surface Structure in Magnesium Oxide Tablets

The Influence of Matrix Technology on the Subdivision of Sustained Release Matrix Tablets.

The subdivision of sustained release tablets is a controversial issue, especially concerning its impact on dissolution profiles. The purpose of this study was to elucidate the behavior upon subdivision of this class of tablets. For this, three common sustained release matrices containing different technologies were selected, e.g., a tablet comprised of a multiple-unit particulate system (MUPS), a lipid matrix tablet, and a polymeric inert matrix tablet. These tablets were studied concerning their physicochemical performance, dissolution rate, and kinetic profile before and after their subdivision. When subdivision occurred in the scoreline, mass variation and mass loss were below the mean values described in the literature. The dissolution of tablets with inert matrices and some lipid tablets that had their matrices preserved along the dissolution was influenced directly by tablet surface area, which increased after the subdivision. Such a result implies possible clinical consequences, especially in the case of drugs with a narrow therapeutic window, such as clomipramine. Conversely, the subdivision of MUPS tablets did not interfere in the dissolution profile since the drug was released from the granules that resulted from tablet disintegration. Hence, MUPS technology is the most recommended to produce sustained release matrix tablets intended for dose adjustment upon subdivision.

Polyaniline as a Precursor of Multi-Layer Graphene: Microscopic and Microspectroscopic Study

Aluminosilicate-based nanocomposites containing multi-layer graphene were prepared from polyaniline/montmorillonite intercalate in two different forms: tablets and thin layers. Starting materials, polyaniline/montmorillonite powder and polyaniline/montmorillonite layers deposited on quartz glass, were prepared by in situ polymerization of aniline in presence of montmorillonite particles. Powder was compacted into tablets using pressure 400 MPa. Samples were calcined at 1300 °C in argon atmosphere and multi-layer graphene was formed from polyaniline in both cases as confirmed by Raman microspectroscopy. Changes in morphology and surface conductivity of uncalcined and calcined samples were observed using atomic force microscopy and conductive atomic force microscopy. Also the differences between surface and internal volume of tablets were studied. Conductive atomic force microscopy revealed that the most conductive areas can be found solely on the edges of aluminosilicate particles formed from montmorillonite during calcination process. Detailed observation of multi-layer graphene in these areas was performed using transmission electron microscopy.