ABSTRACT
Gastro retention dosage forms are obligatory for holding the drug in the stomach for area definite drug discharge by afloat technique. Floating microspheres (FM) of Clopidogrel Bisulphate (CB) were fabricated to increase the drug’s reach to blood and to show elongated drug release.METHODSFM of CB were prepared by the ion gelation (exfoliation) method using ethyl cellulose, carrageenan gum, and sodium alginate. The drug-loaded FM were designed and assessed for their physicochemical characteristics including drug-excipient friendly behaviour by Differential Scanning Calorimetry (DSC) and Fourier Transform Infra-Red (FTIR).RESULTSThe DSC and FTIR study revealed the compatibility of CB with the excipients used. The percentage yield of FM from all formulations was good and showed satisfactory buoyancy and floating time. % CB release for the formulations was found up to 98.5% (F8) till 10th hour. The release kinetics revealed that CB discharge from the devices was best fitted to Hixson Crowell’s model with regression values ranging from 0.887 to 0.989.CONCLUSIONSFM with CB can be formulated using sodium alginate, ethyl cellulose and carrageenan gum by exfoliation gelation method.
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Objective: This study was undertaken to formulate a floating drug delivery system of theophylline hydrochloride using different concentrations of a chosen polymer and then investigate how polymer concentration affects buoyancy and drug release properties of the tablets. Methods: Hydroxypropyl methylcellulose (HPMC) at different concentration levels of 15% (F1), 20% (F2) and 30% (F3) was used to form the three formulation batches of floating tablets. Wet granulation method was used for the granule preparation while Sodium bicarbonate and citric acid were used as the gas generating agent. The physical properties of the granules and the floating tablets were evaluated. Also determined were the physicomechanical properties, buoyancy and swelling characteristics of the tablets. The in vitro drug release study was carried out according to the USP I (basket method) for 8h in 900 ml 0.1N HCl at 50 rpm. Samples withdrawn at the regular predetermined time were analyzed spectrophotometrically at a wavelength of 271 nm and data obtained statistically analyzed by one-way analysis of variance (ANOVA). The differences between means were considered significant at P<0.05. Results: The result showed that polymer (HPMC) concentration significantly (p>0.05) increased swelling index and improved floating lag time, it had no significant effect on the total floating time. Percentage drug release at the end of 8 h was 100%, 98.2% and 96.13% for formulation F1, F2 and F3, respectively. All three formulations followed the Higuchi drug release kinetics model and the mechanism of drug release was the non Fickian diffusion with exponents of 0.46, 0.51 and 0.56 for the respective batch. Conclusion: Batch F3 gave a better-controlled drug release and floating properties in comparison to batch F1 and F2 thus Polymer concentration influenced the onset of floating and controlled the release of Theophylline.
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Objective To study the expression levels of microRNA (miR)-16 and miR-146a in rat lungs of decompres-sion sickness (DCS) caused by fast buoyancy ascent escape or diving .Methods At 0.5 h after fast buoyancy ascent es-cape or diving, the pathological changes in rat lungs and expression levels of miR-16,and miR-146a were detected by re-verse transcription-quantitive polymerase chain reaction and compared with normal control group .Results The pathological characteristics of lungs in two DCS groups were tissue damage .At 0.5 h after DCS caused by fast buoyancy ascent escape , the lung tissue expression levels of miR-16 and miR-146a did not significantly change compared with normal control and diving DCS groups ,but the rat lung tissue expression level of miR-146 a in diving DCS group was obviously increased , com-pared with normal control group .Conclusion miR-146a may play a role in post-transcriptional regulation in the process of diving DCS .
ABSTRACT
Floating matrix tablets of losartan potassium were developed with an aim to prolong its gastric residence time and increase the bioavailability of drug. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. The tablets were prepared by wet granulation technique, using polymers Methocel K15 and Methocel K100 in combination with other standard excipients. Sodium bicarbonate was incorporated as gas generating agent. The effects of sodium bicarbonate and polymers on drug release profile and floating properties were investigated. It was found that viscosity of Methocel K15 and Methocel K100 along with sodium bicarbonate had significant impact on the release and floating properties of the delivery system. The decrease in the release rate was observed with an increase in the viscosity of the polymeric system. Polymer with high viscosity Methocel K100 was shown to be beneficial than low viscosity polymer Methocel K15 in improving the floating properties of gastric floating drug delivery system (GFDDS). The observed difference in the drug release and floating properties of GFDDS could be attributed to the difference in the basic properties of two polymers, Methocel K15 and Methocel K100 due to their water uptake potential and functional group substitution. The release mechanism were explored and described with zero-order, first-order and Korsmeyer-Peppas equations. The drug release profiles and buoyancy of the floating tablets were stable when stored at 40°C/75% RH for 6 months.
ABSTRACT
The purpose of this research was to develop and evaluate effervescent gastric floating tablets of propranolol HCl. The oral delivery of antihypertensive propranolol HCl was facilitated by preparing an effervescent floating dosage form which could increase its absorption in the stomach by increasing the drugs gastric residence time. In the present work, effervescent floating tablets were prepared with a hydrophilic carrier such as polyethylene oxide (PEO WSR N 60K and PEO WSR 303) as a release retarding agent and sodium bicarbonate as a gas generating agent. The prepared tablets were evaluated for all their physicochemical properties, in vitro buoyancy, drug release and rate order kinetics. From the results, P9 was selected as an optimized formulation based on their 12 h drug release, minimal floating lag time and maximum total floating time. The optimized formulation followed first order rate kinetics with erosion mechanism. The optimized formulation was characterized with FTIR studies and no interaction between the drug and the polymers were observed.
El propósito de la presente investigación fue desarrollar y evaluar tabletas flotantes, efervescentes de HCL propranolol. La administración oral del antihipertensivo HCL propranolol se facilitó mediante la preparación de una forma de dosificación flotante y efervescente que permitiría su absorción en el estómago, mediante el aumento del tiempo de residencia gástrico de la droga. En el presente trabajo, las tabletas flotantes efervescentes fueron preparadas con un portador hidrofílico, tal como el óxido de polietileno (PEO WSR N 60K and PEO WSR 303), como agente retardador y bicarbonato de sodio como un agente generador de gas. Se evaluaron todas las propiedades fisicoquímicas de las tabletas preparadas, su flotación in vitro y su tasa de orden cinético. Se seleccionó el P9 a partir de los resultados obtenidos, como una fórmula óptima, basados en la liberación de la droga a las 12 h, tiempo mínimo de retraso para flotación y máximo tiempo total de flotación. La formulación optimizada siguió una tasa cinética de primer orden con mecanismo de erosión. Esta fórmula óptima se caracterizó mediante estudios FITR y no se observó ninguna interacción entre la droga y los polímeros utilizados.
Subject(s)
Propranolol/administration & dosage , Absorption , Administration, Oral , Chemical Phenomena , Chemistry, Pharmaceutical , Cellulose/administration & dosage , Drug Carriers , Drug Delivery Systems , Drug Design , Drug Evaluation, Preclinical , Molecular Structure , Polyethylene Glycols/administration & dosage , Propranolol/pharmacokinetics , Solubility , Spectroscopy, Fourier Transform Infrared , Stomach , Sodium Bicarbonate/administration & dosage , Stearic Acids/administration & dosage , TabletsABSTRACT
Floating matrix tablets of losartan potassium were developed with an aim to prolong its gastric residence time and increase the bioavailability of drug. Rapid gastrointestinal transit could result in incomplete drug release from the drug delivery system above the absorption zone leading to diminished efficacy of the administered dose. The tablets were prepared by wet granulation technique, using polymers Methocel K15 and Methocel K100 in combination with other standard excipients. Sodium bicarbonate was incorporated as gas generating agent. The effects of sodium bicarbonate and polymers on drug release profile and floating properties were investigated. It was found that viscosity of Methocel K15 and Methocel K100 along with sodium bicarbonate had significant impact on the release and floating properties of the delivery system. The decrease in the release rate was observed with an increase in the viscosity of the polymeric system. Polymer with high viscosity Methocel K100 was shown to be beneficial than low viscosity polymer Methocel K15 in improving the floating properties of gastric floating drug delivery system (GFDDS). The observed difference in the drug release and floating properties of GFDDS could be attributed to the difference in the basic properties of two polymers, Methocel K15 and Methocel K100 due to their water uptake potential and functional group substitution. The release mechanism were explored and described with zero-order, first-order and Korsmeyer-Peppas equations. The drug release profiles and buoyancy of the floating tablets were stable when stored at 40°C/75% RH for 6 months.
ABSTRACT
In the present study, the tablets were prepared by melt granulation method, using the polymer, hydroxy propyl methyl cellulose (HPMC K100M) with different amounts and other excipients and sodium bicarbonate as gas generating agent. The present study is to develop a floatable drug delivery system of Levofloxacin hemihydrate for sustained drug delivery and gastric retentive property with special emphasis on optimization of formulations for floating matrix tablets. Thus the study aims to improve the oral bioavailability of the drug and to achieve extended retention in the stomach which may result in prolonged absorption. Tablets were evaluated by different parameters such as weight uniformity, content uniformity, thickness, hardness, IR spectral analysis, in vitro release studies, Buoyancy determination and kinetic analysis of dissolution data, stability studies Levofloxacin floating tablet drug delivery system showed improved in-vitro bioavailability and extended drug release which may favour the reduced dose frequency and patient compliance.
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Dental composites have improved significantly in physical properties over the past few decades. However, polymerization shrinkage and stress is still the major drawback of composites, limiting its use to selected cases. Much effort has been made to make low shrinking composites to overcome this issue and silorane-based composites have recently been introduced into the market. The aim of this study was to measure the volumetric polymerization shrinkage kinetics of a silorane-based composite and compare it with conventional methacrylate-based composites in order to evaluate its effectiveness in reducing polymerization shrinkage. Five commercial methacrylate-based (Beautifil, Z100, Z250, Z350 and Gradia X) and a silorane-based (P90) composites were investigated. The volumetric change of the composites during light polymerization was detected continuously as buoyancy change in distilled water by means of Archemedes'principle, using a newly made volume shrinkage measurement instrument. The null hypothesis was that there were no differences in polymerization shrinkage, peak polymerization shrinkage rate and peak shrinkage time between the silorane-based composite and methacrylate-based composites. The results were as follows: 1. The shrinkage of silorane-based (P90) composites was the lowest (1.48%), and that of Beautifil composite was the highest (2.80%). There were also significant differences between brands among the methacrylate-based composites. 2. Peak polymerization shrinkage rate was the lowest in P90 (0.13%/s) and the highest in Z100 (0.34%/s). 3. The time to reach peak shrinkage rate of the silorane-based composite (P90) was longer (6.7 s) than those of the methacrylate-based composites (2.4-3.1 s). 4. Peak shrinkage rate showed a strong positive correlation with the product of polymerization shrinkage and the inverse of peak shrinkage time (R = 0.95).
Subject(s)
Composite Resins , Kinetics , Light , Polymerization , Polymers , Silorane Resins , WaterABSTRACT
The aim of this study was to clarify the influence of buoyancy on physiological responses during treadmill walking. Six subjects participated in this experiment. The water level was adjusted to the greater trochanter. Normal water (NW) and 1.135 kg/<i>l</i> of specific gravity (high buoyancy ; HB) were set. Oxygen uptake (VO<sub>2</sub>), heart rate (HR), and rating of perceived exertion were measured during exercise. VO<sub>2</sub> in HB at all walking speeds were higher than those in NW significantly. HR enhanced in HB over the walking speed of 70 m/min significantly. It was clear that the workload of walking in HB increased remarkably over the walking speed of 70 m/min. This suggested that the water resistance acted on the phenomenon of increase of the workload in HB. Furthermore, it was suggested that walking in HB was useful for rehabilitation and therapeutic exercise in the low-speed and for physical training in the high-speed.