methylcellulose and titanium-dioxide

The available tooth whitening products in the market contain high concentrations of hydrogen peroxide (H

Topics: 3T3 Cells; Animals; Cattle; Light; Methylcellulose; Mice; Nitrogen Dioxide; Peroxides; Titanium; Tooth Bleaching

The purpose of this article is to study a detailed mechanism of printing when film-coated tablets were irradiated by UV laser at a wavelength of 355 nm.. Hydroxypropylmethylcellulose (HPMC) film containing titanium dioxide (TiO(2)) and the film not containing TiO(2) and TiO(2) powder were lirradiated by the UV laser and estimated by the morphological observation by zoom stereo microscope, thermogravimetric analysis (TGA), total color difference (dE), X-ray powder diffraction (XRD), and dispersive Raman microscopy.. In the case of the film containing TiO(2), the film showed a visible change in its color from white to gray by the UV laser irradiation. By zoom stereo microscope, it was found that the entire UV laser-irradiated area was not grayed uniformly, but many black particles, whose diameter was about 2 microm, were observed on the film. When TiO(2) powder was irradiated by the UV laser, a visible change in its color from white to gray was observed similar to the case of the film containing TiO(2). There were many black particles locally in the UV laser-treated TiO(2) powder by the morphological observation, and these black particles, agglomerates of the grayed oxygen-defected TiO(2), were associated with the visible change of the TiO(2).. It was found that the film-coated tablets were printed utilizing the formation of the black particles by the agglomeration of the grayed oxygen-defected TiO(2) by the UV laser irradiation.

Topics: Cellulose; Hypromellose Derivatives; Lasers; Methylcellulose; Microscopy; Polymers; Printing; Tablets; Technology, Pharmaceutical; Thermogravimetry; Titanium; Ultraviolet Rays; X-Ray Diffraction

The goal of this project was to determine the effect of the thickness of the coating film on the dissolution behavior of tablets. Commercially available film-coated tablets containing aspirin, acetaminophen and caffeine, were used as the model system. First, a non-destructive X-ray microdiffractometric technique was developed to quantify the thickness of the film-coating in intact tablets. The same tablets were then subjected to dissolution tests. There was an inverse correlation between the cumulative amount of drug in solution at 5min and the thickness of the coating film. As the coating thickness increased, the initiation of tablet dissolution was delayed, resulting in a decrease in the cumulative amount of drug in solution. Finally, the technique was applied to formulations marketed by different companies. The X-ray microdiffractometric technique has the potential to predict the dissolution behavior of tablets.

Topics: Acetaminophen; Aspirin; Caffeine; Chemistry, Pharmaceutical; Drug Compounding; Excipients; Hypromellose Derivatives; Kinetics; Methylcellulose; Microscopy, Electron, Scanning; Powder Diffraction; Solubility; Surface Properties; Tablets; Technology, Pharmaceutical; Titanium; X-Ray Diffraction

The objective of the present study was to develop a practical method to prepare a stable dispersion of TiO2 nanoparticles for biological studies. To address this matter a variety of different approaches for suspension of nanoparticles were conducted. TiO2 (rutile/anatase) dispersions were prepared in distilled water following by treated with different ultrasound energies and various dispersion stabilizers (1.0% carboxymethyl cellulose, 0.5% hydroxypropyl methyl cellulose K4M, 100% fetal bovine serum, and 2.5% bovine serum albumin). The average size of dispersed TiO2 (rutile/anatase) nanoparticles was measured by dynamic light scattering device. Agglomerate sizes of TiO2 in distilled water and 100% FBS were estimated using TEM analysis. Sedimentation rate of TiO2 (rutile/anatase) nanoparticles in dispersion was monitored by optical absorbance detection. In vitro cytotoxicity of various stabilizers in 16-HBE cells was measured using MTT assay. The optimized process for preparation of TiO2 (rutile/anatase) nanoparticles dispersion was first to vibrate the nanoparticles by vortex and disperse particles by ultrasonic vibration in distilled water, then to add dispersion stabilizers to the dispersion, and finally to sonicate the nanoparticles in dispersion. TiO2 (rutile/anatase) nanoparticles were disaggregated sufficiently with an ultrasound energy of 33 W for 10 min. The formation of TiO2 (rutile/anatase) agglomerates in distilled water was decreased obviously by addition of 1.0% CMC, 0.5% HPMC K4M, 100% FBS and 2.5% BSA. For the benefit of cell growth, FBS is the most suitable stabilizer for preparation of TiO2 (rutile/anatase) particle dispersions and subsequent investigation of the in vivo and in vitro behavior of TiO2 (rutile/anatase) nanoparticles. This method is practicable to prepare a stable dispersion of TiO2 (rutile/anatase) nanoparticles for at least 120 h.

Topics: Absorption; Animals; Carboxymethylcellulose Sodium; Cattle; Cell Line; Cell Survival; Drug Stability; Humans; Hypromellose Derivatives; Metal Nanoparticles; Methylcellulose; Particle Size; Serum; Serum Albumin, Bovine; Titanium; Ultrasonics; Vibration

The aim of the study was to explore the drug release mechanism from pellets, coated with blends of poly(vinyl acetate) (PVAc) and polyvinyl alcohol-polyethylene glycol graft copolymer (PVA-PEG). Water influx and drug solubilization inside the pellets were investigated in correlation to drug release. The highly soluble drug Chlorpheniramine maleate (CPM) was used as a model compound. Modified release pellets were manufactured by fluid bed drug layering and film coating of starter beads. The pellets were characterized using cross section EDX mapping, confirming location and homogeneity of the different layers. A film coat of 23%, containing PVAc/PVA-PEG in 9:1 ratio, resulted in a sigmoid shaped release curve with 2 h lag-time, followed by 3 h of continuous drug release. Using NMR analysis, water influx and drug solubilization inside the pellets were detected within 20 min. Additionally, dissolution of PVA-PEG after several minutes and drug release after the lag-time were measurable. A fast water influx into PVAc/PVA-PEG film coated pellets did not result in a fast drug release. Despite a fast drug solubilization within the pellets, drug release was initiated after 2 h, suggesting a one way stream of water during the observed lag-time.

Topics: Biological Availability; Cellulose; Chlorine; Chlorpheniramine; Delayed-Action Preparations; Deuterium Oxide; Drug Implants; Hydrogen-Ion Concentration; Hypromellose Derivatives; Magnesium; Magnetic Resonance Spectroscopy; Methylcellulose; Microscopy, Electron, Scanning; Oxygen; Polyethylene Glycols; Polyvinyl Alcohol; Polyvinyls; Silicon; Spectrometry, X-Ray Emission; Talc; Titanium; Water

Raman spectra of a set of coated pharmaceutical tablets were analyzed for the purpose of calibrating the spectra to tablet coating thickness. Acetaminophen tablets were coated with a hydroxypropylmethylcellulose/polyethylene glycol film coating whose thickness was varied from 0 to 6% weight gain. Coatings were also prepared with two concentrations of TiO2 at several film thicknesses. The resulting spectral data set was analyzed using several different multivariate calibration procedures. The procedures examined in this study included spectral correction followed by target factor analysis, spectral correction with baseline subtraction followed by principal component regression, and first derivative computation followed by principal component regression. The results demonstrate that target factor analysis is a viable method for calibration of Raman spectra to tablet coating thickness. Calibration based on derivative spectra resulted in linear correlation that was equal to that of the results of target factor analysis for coatings without TiO2. However, target factor analysis was found to be superior to other methods when TiO2 was present in the tablet coatings. The effect of sample fluorescence on each of these chemometric methods was also examined. It was found that when photobleaching of fluorescent impurities due to exposure to the Raman excitation source was controlled, the tablet coating thickness could be calibrated to the intensity of the fluorescence signal. The results also demonstrate that for the samples examined here, calibration by target factor analysis is insensitive to variation in fluorescent intensity when the tablet coating emission spectrum is included in the matrix of target vectors.

Topics: Acetaminophen; Algorithms; Analgesics, Non-Narcotic; Calibration; Coloring Agents; Data Interpretation, Statistical; Excipients; Fluorescent Dyes; Hypromellose Derivatives; Indicators and Reagents; Methylcellulose; Models, Chemical; Photobleaching; Polyethylene Glycols; Spectrum Analysis, Raman; Tablets; Titanium

The purpose of this study was to evaluate the change of surface roughness and the development of the film during the film coating process using laser profilometer roughness measurements, SEM imaging, and energy dispersive X-ray (EDX) analysis. Surface roughness and texture changes developing during the process of film coating tablets were studied by noncontact laser profilometry and scanning electron microscopy (SEM). An EDX analysis was used to monitor the magnesium stearate and titanium dioxide of the tablets. The tablet cores were film coated with aqueous hydroxypropyl methylcellulose, and the film coating was performed using an instrumented pilot-scale side-vented drum coater. The SEM images of the film-coated tablets showed that within the first 30 minutes, the surface of the tablet cores was completely covered with a thin film. The magnesium signal that was monitored by SEM-EDX disappeared after ~15 to 30 minutes, indicating that the tablet surface was homogeneously covered with film coating. The surface roughness started to increase from the beginning of the coating process, and the increase in the roughness broke off after 30 minutes of spraying. The results clearly showed that the surface roughness of the tablets increased until the film coating covered the whole surface area of the tablets, corresponding to a coating time period of 15 to 30 minutes (from the beginning of the spraying phase). Thereafter, the film only became thicker. The methods used in this study were applicable in the visualization of the changes caused by the film coating on the tablet surfaces.

Topics: Coated Materials, Biocompatible; Drug Compounding; Hypromellose Derivatives; Materials Testing; Membranes, Artificial; Methylcellulose; Stearic Acids; Surface Properties; Tablets; Titanium

Pastes are semisolid stiff preparations containing a high proportion of finely powdered material. Powders such as zinc oxide, titanium dioxide, starch, kaolin or talc are incorporated in high concentrations into a preferably lipophilic, greasy vehicle. A clinically distinctive feature which is generally attributed to pastes is the quality to absorb exudates by nature of the powder or other absorptive components. Reviewing the various pharmacopoeias serious doubts arise from the various formulas of pastes and their absorptive features. The zinc oxide pastes of the USP XXII, the DAB 10 and BP 88 (US, German and British pharmacopoeias). are composed of petrolatum, zinc oxide and starch. Petrolatum, a highly lipophilic, water-immiscible vehicle surrounds the powder particles preventing any absorption of water or exudates.. The goal of our investigation was to test a simple experimental setting to characterize the clinically important absorptive feature of powders and pastes.. The absorptive features of the powders were determined by the method of Enslin. The absorptive features of the paste preparations were calculated from the weight difference between the paste preparation before and after incubation with water using a simple standardized procedure.. The absorptive features of titanium dioxide, zinc oxide, kaolin, corn starch and methylcellulose powder in pharmacopoeia quality were determined. Zinc oxide and kaolin powder showed the highest absorption of 1,000 mg water/g powder (100%). The water absorption of corn starch and titanium dioxide was 700 and 450 mg/g powder, respectively. The absorptive features of a series of paste preparations were studied in a simple experimental setting. The data show that two-phase pastes consisting of two immiscible components, one (the dispersed or inner phase; powder) being suspended in the other (the continuous or outer phase; lipophilic vehicle), have no absorptive features. In contrast, three-phase pastes consisting of a hydrophilic two-phase emulsion with high concentrations of incorporated powder (cream pastes) show considerable water uptake.. We conclude that the classical two-phase pastes such as the zinc oxide pastes have no absorptive features. On the contrary, these formulations are highly occlusive. Therefore lipophilic pastes are only indicated when protection of intact skin against aggressive body exudates and humidity is required. The hydrophilic three-phase pastes or cream pastes show considerable water uptake and fulfil common expectations of pastes to dry the skin.

Topics: Absorption; Calcium Hydroxide; Dermatologic Agents; Emulsions; Kaolin; Lipids; Methylcellulose; Mineral Oil; Ointments; Oleic Acid; Oleic Acids; Peanut Oil; Plant Oils; Polyethylene Glycols; Powders; Simethicone; Starch; Suspensions; Titanium; Water; Zinc Oxide

Stress crack resistance parameters--tensile strength: Young's modulus ratio, relative surface energy, and toughness index--have been examined for unpigmented free films of hydroxypropyl methylcellulose containing polyvinyl alcohol, and polyethylene glycols 400 and 1000, as well as similar film systems pigmented with either talc or titanium dioxide. Incorporation of either polyvinyl alcohol or polyethylene glycols 400 and 1000 in hydroxypropyl methylcellulose film coatings eliminated the incidence of edge splitting in the coated tablets. Increase in pigment concentration generally led to a decrease in the crack resistance of pigmented films. There was a relation between the stress crack resistance of pigmented free films and the incidence of edge splitting of corresponding film coatings applied to aspirin tablets--generally, the higher the crack resistance the lower the incidence of edge splitting. A similar relationship applied to the unpigmented films only when the tensile strength: Young's modulus ratio was considered.

Topics: Aspirin; Hardness; Hypromellose Derivatives; Methylcellulose; Polyethylene Glycols; Tablets, Enteric-Coated; Talc; Tensile Strength; Titanium

The tensile properties of representative tablet film coating systems, containing hydroxypropyl methylcellulose alone and in combination with either polyvinyl alcohol, polyethylene glycol 400 and polyethylene glycol 1000 and pigmented with either talc or titanium dioxide, have been investigated. Tensile anisotropy was observed between film samples cut parallel to, and perpendicular to, the direction of rotation of the casting substrate and factors accounting for this phenomenon are presented.

Topics: Chemistry, Pharmaceutical; Hypromellose Derivatives; Methylcellulose; Tablets, Enteric-Coated; Talc; Tensile Strength; Titanium