Diffusion Release Research Articles

Anticancer activity and pharmacokinetics of TanshinoneⅡA derivative supramolecular hydrogels

In this work, we studied the synthesis, characterization, anticancer effect and pharmacokinetics of supramolecular hydrogels composed of 2-naphthalene acetic acid-Gly-Arg-Gly-Asp-Phe-Phe-Gly poly-peptide (Nap-peptide) and TanshinoneⅡA (TsⅡA) derivative (Ts-OH) which had excellent selectivity for inhibiting growth of cancer cells. The Nap-Ts hydrogels exhibited long, narrow and flexible nanofibers entangling each other to form three-dimensional networks, which further self-assembling into nanoparticles with diameters from 200 to 300 nm. The hydrogels drug delivery was suitable for the sustained release, which exhibited both diffusion and relaxation release mechanisms. Compared to TsⅡA, the Ts-OH, Nap-Ts hydrogels exhibited higher anticancer effect to SCG7901 cells, MCF-7 cells, HepG2 cells and MDA-MB-231 cells in vitro. The pharmacokinetic behaviours of Nap-Ts hydrogels were evaluated in rats. The Nap-Ts hydrogels possessed better biocompatibility, sustain drug release and anticancer effect than TsⅡA. The results demonstrated the potential drug delivery system of TsⅡA improving the anticancer activity.

Site-specific tunable drug release from biocompatible tragacanth-cl-polyacrylamide polymer networks

In present study, tragacanth gum-based pH-responsive tunable drug delivery devices have been synthesized. The relation between synthetic reaction parameters during polymerization reaction and swelling and drug release from polymers has also been studied. Polymers were characterized by FTIR, blood compatibility and swelling studies. Swelling of TG-cl-poly(AAm) polymers decreased with an increase in feed monomer [AAm] and cross-linker [NN-MBA] concentration. Polymer showed pH-responsive swelling nature as swelling increased with an increase in pH of solution. The swelling and drug release occurred through non-Fickian diffusion mechanism and release profile obey Korsmeyer–Peppas model of drug release. There is no rapid increase in drug release rate from drug-loaded polymers which is a required characteristic for controlled drug delivery system. TG-cl-poly(AAm) polymers are found to be non-thrombogenic, haemo-compatible during blood-compatibility studies. These polysaccharide based polymers can be tailored for developing site-specific biocompatible delivery devices to enhance local and systemic bioavailability of loaded curative agents.

Radiation-induced graft copolymerization of N‑vinyl imidazole onto moringa gum polysaccharide for making hydrogels for biomedical applications

Keeping in view the importance of polysaccharide gum in the pharmaceutical formulations, in the present work, exploration of the potential of the moringa gum in hydrogel formation for drug delivery applications has been carried out. The gum based hydrogels were prepared via radiation induced graft-copolymerization of N‑vinyl imidazole onto the gum. The polymers were characterized by cryo-SEM, AFM, FTIR, 13C NMR spectroscopy and swelling studies. Some properties of the polymers such as blood compatibility, antioxidant activity, and mucoadhesion and gel strength were also determined along with the evaluation of the drug release profile of an antibiotic drug levofloxacin. The slow release of drug was observed without burst effect from the drug loaded hydrogels. Release of the drug followed non-Fickian diffusion mechanism and release profile was best fitted in in Hixson-Crowell kinetic model. Cryo-SEM showed the porous nature of the hydrogels and AFM analysis confirmed the surface roughness. The polymers were found to be non-haemolytic mucoadhesive and antioxidant in nature with pore size = 12.09 nm and crosslinking density = 9.13 × 10−5 mol cm−3. These results indicated that these pure and sterile polymers can be proposed as a gastrointestinal drug delivery system.

Hydrogel formation by radiation induced crosslinked copolymerization of acrylamide onto moringa gum for use in drug delivery applications

Keeping in view the importance of polysaccharides gum in designing drug delivery systems, the present work is the exploration of the potential of the moringa gum in hydrogel formation via radiation induced crosslinking method for drug delivery applications. These polymers were characterized by cryo-SEM, AFM, FTIR, 13C–NMR spectroscopy and swelling studies. Some properties of the polymers such as blood compatibility, antioxidant activity, mucoadhesion and gel strength were also determined along with the evaluation of drug release profile of an antibiotic drug levofloxacin. The slow release of drug was observed without burst effect from the drug loaded hydrogels. Release of drug occurred through non-Fickian diffusion mechanism and release profile best fitted in Korsmeyer-Peppas kinetic model. Cryo-SEM showed the porous nature of the hydrogels. The polymers were found to be mucoadhesive and antioxidant in nature. These results indicated that these pure and sterile polymers can be proposed as gastrointestinal drug delivery system.

A Model of Transport and Transformation of Biogenic Elements in the Coastal System and Its Numerical Implementation

A discrete mathematical model of hydrobiology of coastal zone is constructed and analyzed. The model takes into account the transport and transformation of polluting biogenic elements in water basins. The propagation and transformation of biogenic elements is affected by such physical factors as three-dimensional motion of water taking into account the advective transport and microturbulent diffusion, spatially inhomogeneous distribution of temperature, salinity, and oxygen. Biogenic pollutants typically arrive into the water basin with river flow, which depends on the weather and climate of the geographic region, or with drainage of insufficiently purified domestic and industrial waste or other kinds of anthropogenic impact. Biogenic pollutants can also appear due to secondary pollution processes, such as stirring up and transport of bed silt, shore abrasion, etc. Stoichiometric relations between biogenic nutrients for phytoplankton algae that can be used to determine the limiting nutrient for each species are obtained. Observation models describing the consumption, accumulation of nutrients, and growth of phytoplankton are considered. A three-dimensional mathematical model of transformation of forms of phosphorus, nitrogen, and silicon in the plankton dynamics problem in coastal systems is constructed and analyzed. This model takes into account the convective and diffusive transport, absorption, and release of nutrients by phytoplankton as well as transformation cycles of phosphorus, nitrogen, and silicon forms. Numerical methods for solving the problem that are based on high-order weighted finite difference schemes and take into account the degree of fill of the computation domain control cells are developed. These methods are implemented on a multiprocessing system. They make it possible to improve the accuracy of the numerical solution and decrease the computation time by several fold. Based on the numerical implementation, dangerous phenomena in coastal systems related to the propagation of pollutants, including oil spill, eutrophication, and algae bloom, which causes suffocation phenomena in water basins, are reconstructed.

Kinetic study, structural analysis and computational investigation of novel xerogel based on drug-PEG/SiO2 for controlled release of enrofloxacin

A sustained drug delivery system is developed by using nonionic polymer to formulate drug release rate from silica based capsules. To serve this purpose, silica based capsules filled with poly(ethylene glycol) (PEG) were incorporated with a veterinary antibiotic drug enrofloxacin (EFX); as a model hydrophobic drug by using a general and facile sol-gel route. The physicochemical properties of the prepared drug-loaded composites were investigated by scanning electron microscope (SEM), nitrogen adsorption, Fourier transform infrared spectroscopy and thermal analysis (TGA). The impact of the media's ionic strength on the drug release was evaluated over a range of 0–0.4 M to simulate the gastrointestinal feed in two physiological pH conditions. Sodium chloride was applied for ionic concentration adjustment due to its ability to salt out polymers in the midrange of the lyotropic series. Simultaneously, the drug release kinetics was evaluated by fitting experimental data to common empirical (zero-order, first order and Higuchi) and semi-empirical (Ritger-Peppas and Sahlin-Peppas) models. The drug release kinetics from capsules revealed a non-Fickian diffusion and pure relaxation-controlled release. Of these models, Sahlin-Peppas equation best fit the release data of EFX. To determine the best model, non-linear regressions were carried out. Furthermore, we compare a computational model to experimental data for drug-polymer and drug-SiO2 interactions at B3LYP/6-31 + G(d) level of theory. This model has been suggested based on the active sites of its component, which are characterized by MEP. Finally, the HOMO-LUMO and vibrational analysis were performed.

Predicting Insulin Secretion Profiles for Immunoisolating Devices with Transplanted Islets

Avascular islets or stem cells transplanted under immunoisolating conditions offer considerable hope in overcoming the challenges of islet transplantation; however, because of diffusional limitations, implants face long-term viability and efficiency-of-response problems. To quantitatively characterize the glucose-stimulated insulin release of pancreatic islets, we conducted parallel dynamic perifusion experiments with free and hydrogel encapsulated islets. Perifused human islets secreted less insulin than murine islets per unit mass (IEQ) and had a less pronounced first-phase peak. The data was used to develop a computational model of insulin secretion. Our model couples hormone secretion and nutrient consumption kinetics with diffusive and convective transport, fits well the experimental data, and can be used to predict insulin release profiles for arbitrary geometries and glucose challenges. We found that larger diffusion distances (larger capsules) unavoidably dampen the first-phase insulin response, resulting in a sustained-release type insulin secretion that sluggishly responds to changes in glucose concentration. Hence, bioartificial pancreas devices can provide long-term and physiologically desirable solutions only if immunoisolation and biocompatibility considerations are considered together with optimized nutrient diffusion and insulin release characteristics. Disclosure P. Buchwald: None. A.A. Tomei: Consultant; Self; EyePharma. Research Support; Self; Semma Therapeutics, Inc.. Stock/Shareholder; Self; Converge Biotech Pvt. Ltd.. C.L. Stabler: None.

FORMULATION AND EVALUATION OF TROPICAMIDE IN-SITU GELS LOADED SOLID LIPID NANOPARTICLES FOR OCULAR DRUG DELIVERY

The aim of present work Formulation and Evaluation of Tropicamide In-situ Gels loaded Solid Lipid Nanoparticles for Ocular Drug Delivery. The surface morphological of SLN was carried out by TEM. The Tropicamide loaded solid lipid nanoparticles was measured the average particle size was ranges from 182.1+3.12nm to 390.1±2.10 nm. The zeta potential ranges from -0.17±1.4 mV to -3.80±1.5 mV. The entrapment efficiency 66.2 % to 89.2 %. Drug content was ranges from 0.112mg/ml to 0.502 mg/ml. The percentage yield ranges from was ranges from 0.112mg/ml to 0.502 mg/ml. The polydispersity index ranged from 1.011±0.15 to 1.327±0.13. These SLN enriched in Chitosan gels the pH of the formulations range from 6.8 to 6.9. The gelling strength ranged from 129 sec to 152 sec. The bioadhesive force was ranges from 10.21 ±1.15 dynes/cm2 to 15.23 ± 1.22 dynes/cm2. The viscosity was ranges from 2212 ± 1.14 cps to 2420± 1.19 cps. The spreadability coefficient was ranges from 11.2 ± 1.10 gms/sec to 13.3 ± 1.21 gms/sec. The in-vitro diffusion release studies carried out at 12 hrs TSLNGF19 shows the 79.2 ± 0.32. The ex vivo permeation studies for optimized formulation the increased drug permeation and corneal accumulation. In vitro corneal permeation profile of tropicamide loaded SLN from the chitosan gels and commercial eye drop solution (Tropicacyl) across the isolated porcine cornea. The ocular tolerance studies performed with HETCAM assay, corneal hydration study, histopathological studies. The stability studies of chitosan gels for long-term stability as per ICH guidelines (25°C ± 2°C / 60% RH ± 5% RH) &accelerated stability as per ICH guidelines (40°C ± 2°C / 75% RH ± 5% RH) there is no changes in gelling strength, bioadhesive force, viscosity, spreadability coefficient in optimized formulation. Keywords: Chitosan, Corneal hydration studies, ex vivo permeation, in vitro diffusion studies, Solid Lipid Nanoparticles

Extrasynaptic Neurotransmission Mediated by Exocytosis and Diffusive Release of Transmitter Substances.

This review article deals with the mechanisms of extrasynaptic release of transmitter substances, namely the release from the soma, axon and dendrites in the absence of postsynaptic counterparts. Extrasynaptic release occurs by exocytosis or diffusion. Spillover from the synaptic cleft also contributes to extrasynaptic neurotransmission. Here, we first describe two well-known examples of exocytosis from the neuronal soma, which may release copious amounts of transmitter for up to hundreds of seconds after electrical stimulation. The mechanisms for somatic exocytosis of the low molecular weight transmitter serotonin, and the peptides oxytocin and vasopressin have been studied in detail. Serotonin release from leech neurons and oxytocin and vasopressin from rodent neurons have a common multi-step mechanism, which is completely different from that for exocytosis from presynaptic endings. Most transmitters and peptides released extrasynaptically seem to follow this same mechanism. Extrasynaptic exocytosis may occur onto glial cells, which act as intermediaries for long-term and long-distance transmission. The second part of this review article focuses on the release upon synthesis of the representative diffusible molecules nitric oxide (NO) and endocannabinoids. Diffusible molecules are synthesized “on demand” from postsynaptic terminals in response to electrical activity and intracellular calcium elevations. Their effects include the retrograde modulation of presynaptic electrical activity and transmitter release. Extrasynaptic neurotransmission is well exemplified in the retina. Light-evoked extrasynaptic communication sets the gain for visual responses and integrates the activity of neurons, glia and blood vessels. Understanding how extrasynaptic communication changes the function of hard-wired circuits has become fundamental to understand the function of the nervous system.

Cytotoxicity of doxrubicin loaded single-walled carbon nanotubes.

Carbon nanotube (CNTs) is a new alternative for efficient drug delivery and it has a great potential to change drug delivery system profile in pharmaceutical industry. One of the important advantage of CNTs is their needle-like, cylindrical shape. This shape provides a high surface area for multiple connections and adsorption onto for millions of therapeutic molecules. CNTs can be internalized by cells via endocytosis, passive diffusion and phagocytosis and release the drug with different effects like pH and temperature. The acidic nature of cancer cells and the susceptibility of CNTs to release the drug in the acidic environment have made it a promising area of research in cancer drug delivery. In this research, we investigated cell viability, cytotoxicity and drug delivery in breast cancer cell line by designing non-covalent single walled carbon nanotubes (SWNT)-doxorubicin (DOX) supramolecular complex that can be developed for cancer therapy. Applied high concentrations of DOX loaded SWNTs changed the actin structure of the cells and prevented the proliferation of the cells. It was showed that doxorubicin loaded SWNTs were more effective than free doxorubicin at relatively small concentrations. Once we applied same procedure for short and long (short: 1-1.3µm; long: 2.5-4µm) SWNTs and compared the results, more disrupted cell structure and reduction in cell proliferation were observed for long CNTs. DOX is bounded more to nanotubes in basic medium, less bound in acidic environment. Cancer cells were also examined for concentration at which they were effective by applying DOX and it was seen that 3.68µM doxorubicin kills more than 55% of the cells.

Modification of sterculia gum polysaccharide via network formation by radiation induced crosslinking polymerization for biomedical applications

AimsKeeping in view the therapeutic and pharmaceutical applications of sterculia gum polysaccharide in consideration, its modification has been carried out through grafting and crosslinking to develop the hydrogels for enhanced biomedical applications. Radiation method was used for formation of sterile network of sterculia gum, carbopol and graphene oxide (GO). These polymers were characterized by Cryo-SEMs, AFM, 13C NMR solid state, swelling studies. Some biomedical properties of hydrogels like thrombogenicity, haemolytic potential, antioxidant activity, mucoadhesion and gel strength were determined along with the drug delivery studies. ScopeIn the present work, sterile polysaccharide gum based drug delivery system was developed for the slow delivery of gemcitabine, an anti-cancer drug, to overcome its side. ConclusionsThe release profile of anti-cancer drug “gemcitabine” followed non-Fickian diffusion mechanism and release profile was best fitted in Korsmeyer-Peppas kinetic model of drug release. The hydrogels were found to be non-thrombogenic, non-haemolytic, mucoadhesive and antioxidant in nature. Incorporation of the GO nano-sheets in the composite hydrogel matrix has improved its mechanical and drug delivery properties and also exerted strong influence on the network density and mesh size of the hydrogels.

Films based on κ-carrageenan incorporated with curcumin for freshness monitoring

Novel films based on κ-carrageenan (Car) incorporated with curcumin (Cur) were developed for freshness monitoring of foods. Cur and Car were interacted by hydrogen bonds. A low amount of Cur (no higher than 3%) could be well-dispersed in Car matrix. These characteristics significantly improved the film barrier and tensile strength, besides the enhancement of thermal stability. Hence, the Car film with 3% Cur exhibited the best performance. The films showed a good release control of Cur and a predominant Fickian diffusion release mechanism, which was favorable to sustainable pH change sensing. The Car-Cur films demonstrated a strong redness-shift under alkaline condition. This characteristic was successfully used to monitor the spoilage of pork and shrimp during storage. As a pH colorimetric indicator, the Cur incorporated Car films may have a great potential in the freshness monitoring of foods.

Development of Novel Biodegradable Enrofloxacin–Silica Composite for In Vitro Drug Release Kinetic Studies

A sustained drug delivery system is developed by using nonionic polymer to formulate drug release rate from silica capsules. To serve this purpose, silica capsules filled with poly(ethylene glycol) (PEG) were incorporated with a veterinary antibiotic drug enrofloxacin (ENF); as a model hydrophobic drug by using a general and facile sol–gel route. The physicochemical properties of the prepared drug-loaded composites were investigated by scanning electron microscope (SEM), nitrogen adsorption, Fourier transform infrared spectroscopy and thermal analysis (TGA). The impact of the media’s ionic strength on the drug release was evaluated over a range of 0–0.4 M to simulate the gastrointestinal feed in two physiological pH conditions. Sodium chloride was applied for ionic concentration adjustment due to its ability to salt out polymers in the midrange of the lyotropic series. Simultaneously, the drug release kinetics was evaluated by fitting experimental data to common empirical (zero-order, first order and Higuchi) and semi-empirical (Ritger–Peppas and Sahlin–Peppas) models. The drug release kinetics from capsules revealed a non-Fickian diffusion and pure relaxation-controlled release. Of these models, Sahlin–Peppas equation best fit the release data of ENF. To determine the best model, non-linear regressions were carried out.

Use of seaweed and filamentous fungus derived polysaccharides in the development of alginate-chitosan edible films containing fucoidan: Study of moisture sorption, polyphenol release and antioxidant properties

Alginate and fucoidan extracted from the brown macroalga Sargassum latifolium and chitosan derived from the filamentous fungus Aspergillus niger were used for the development of edible films with natural antioxidant properties. The incorporation of fucoidan and/or Ca2+ into the alginate-chitosan films decreased water solubility, but increased film thickness, water vapor permeability and oxygen permeability. The developed films showed good barrier properties against ultraviolet light. The interactions between film components were investigated using FTIR analysis which confirmed the presence of hydrogen bonded interaction. Kinetics of moisture sorption and polyphenol release exhibited a good fit to Peleg's model. Film moisture content at equilibrium was increased by fucoidan blending. Additionally, the water vapor diffusion and polyphenol release were expressed in terms of effective diffusion coefficient based on simplified Fick's second law. The developed films exhibited good antioxidant properties as measured by total antioxidant assay, ferric reducing antioxidant power and hydroxyl radical scavenging activity. Both film type and the type of the food simulant markedly affected the polyphenol release and the subsequent antioxidant activity of the films.

Use of the brown seaweed Sargassum latifolium in the design of alginate-fucoidan based films with natural antioxidant properties and kinetic modeling of moisture sorption and polyphenolic release

Alginate and fucoidan are unique polysaccharides present in brown algae and widely used in food and medical technologies. Alginate and fucoidan were sequentially extracted from Sargassum latifolium and used for the preparation of alginate and alginate-fucoidan blend films with or without Ca-crosslinking. The incorporation of fucoidan and Ca2+ decreased water solubility, but increased film thickness, water vapor permeability and oxygen permeability. The films showed good properties against ultraviolet light, however, incorporation of fucoidan and/or Ca2+ decreased the color parameter L* value and increased the a* and b* values of the films. The interaction of Ca2+ and fucoidan with alginate was investigated using FTIR analysis which confirmed the presence of hydrogen bonded interaction. Kinetics of moisture sorption and polyphenol release exhibited a good fit to Peleg's model. Ca2+ crosslinking decreased initial moisture sorption and increased the maximum sorption capacity of the films. Additionally, the water vapor diffusion and polyphenol release were expressed in terms of effective diffusion coefficient based on simplified Fick's law. The developed films showed good antioxidant properties as measured by total antioxidant assay, ferric reducing antioxidant power and hydroxyl radical scavenging activity. Both film type and the type of the food simulant markedly affected the polyphenol release and the antioxidant activity of the films.

Preparation of Fish Skin Gelatin-Based Nanofibers Incorporating Cinnamaldehyde by Solution Blow Spinning.

Cinnamaldehyde, a natural preservative that can non-specifically deactivate foodborne pathogens, was successfully incorporated into fish skin gelatin (FSG) solutions and blow spun into uniform nanofibers. The effects of cinnamaldehyde ratios (5–30%, w/w FSG) on physicochemical properties of fiber-forming emulsions (FFEs) and their nanofibers were investigated. Higher ratios resulted in higher values in particle size and viscosity of FFEs, as well as higher values in diameter of nanofibers. Loss of cinnamaldehyde was observed during solution blow spinning (SBS) process and cinnamaldehyde was mainly located on the surface of resultant nanofibers. Nanofibers all showed antibacterial activity by direct diffusion and vapor release against Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes. Inhibition zones increased as cinnamaldehyde ratio increased. Nanofibers showed larger inhibition effects than films prepared by casting method when S. typhimurium was exposed to the released cinnamaldehyde vapor, although films had higher remaining cinnamaldehyde than nanofibers after preparation. Lower temperature was favorable for cinnamaldehyde retention, and nanofibers added with 10% cinnamaldehyde ratio showed the highest retention over eight-weeks of storage. Results suggest that FSG nanofibers can be prepared by SBS as carriers for antimicrobials.

Drug self-assembly for synthesis of highly-loaded antimicrobial drug-silica particles

Antimicrobial drug release from biomaterials for orthopedic repair and dental restorations can prevent biofilm growth and caries formation. Carriers for drug incorporation would benefit from long-term drug storage, controlled release, and structural stability. Mesoporous silica, synthesized through a co-assembly of silica and surfactant template, is an ideal drug encapsulation scaffold that maintains structural integrity upon release. However, conventional loading of drug within meso-silica pores via concentration-gradient diffusion limits the overall payload, concentration uniformity, and drug release control. Herein we demonstrate the co-assembly of an antimicrobial drug (octenidine dihydrochloride, OCT), and silica, to form highly-loaded (35% wt.) OCT-silica nanocomposite spheres of 500 nm diameter. Drug release significantly outlasted conventional OCT-loaded mesoporous silica, closely fit Higuchi models of diffusive release, and was visualized via electron microscopy. Extension of this concept to the broad collection of self-assembling drugs grants biomedical community a powerful tool for synthesizing drug-loaded inorganic nanomaterials from the bottom-up.

Analytical Approach to Estimate Salt Release from Tailings Sand Hummocks in Oil Sands Mine Closure

Integrated surface water and groundwater models are well suited for evaluating the long-term performance of oil sands mine closure landscapes to optimize reclamation designs that satisfy performance criteria. However, the scale of the problem makes it difficult to evaluate a large number of design alternatives using numerical models, while at the same time satisfying numerical criteria, such as the courant and peclet numbers. The problem becomes particularly challenging in the design of permeable sand tailings hummocks overlying relatively impermeable composite tailings, where vertical advective flushing of process-affected water through the tailings hummocks is coupled to lateral transport of diffusive release from the underlying composite tailings. We developed an analytical solution that rapidly estimates long-term mass loadings from the sand tailings without the challenges typically associated with numerical modelling. Advection and dispersion in the flushing zones, progressive diffusion into underlying low permeability layers, and purely diffusive release are all considered. A comparison of the analytical solutions to numerical simulations for a series of simple hypothetical cases demonstrated that the analytical solutions provide a reasonable simulation of the mass loadings from the reclaimed landscapes over the design life. Although the approach needs to be further verified and validated for more realistic complex mine reclamation conditions, the analytical framework provides a foundation for hydrologic analysis in mine reclamation and closure in the northern boreal environment.

OPTIMIZED DELIVERY OF DICLOFENAC SODIUM FORMULATED IN A SUSTAINED RELEASE RAPHIA AFRICANA HYDROCOLLOID MATRIX

Objective: The aim of this research work was to comparatively study various proportions of a natural hydrocolloid-Raphia africana, and polyvinylpyrrolidone (PVP) as release sustaining agents in diclofenac sodium tablet formulation.Methods: The purified hydrocolloid (R. africana) was characterized by evaluating its organoleptic, physicochemical and flow properties. Diclofenac-polymer ratios of 1:0, 1:0.2, 1:0.4, 1:0.6, and 1:0.8 were employed to produce different granule batches using wet granulation method (that is, the drug was formulated with 0, 5, 10, 15 and 20 % w/w of either R. africana hydrocolloid or PVP, and coded DWB-00, DRA-05, DRA-10, DRA-15, DRA-20, DPP-05, DPP-10, DPP-15 and DPP-20, respectively). Flow properties of granules were studied by determining bulk density, tapped density, Carr’s index, and Hausner’s ratio for all the formulations. Compressed tablets were evaluated using various parameters as weight variation, friability, hardness, tablet thickness and diameter, content uniformity and in vitro dissolution evaluated in phosphate buffer (pH 7.3).Results: Flowability, mechanical and release parameters determined were within pharmacopoeial limits. Generally, the values of bulk and tapped densities increase as binder concentrations increase for both PVP and R. africana hydrocolloid. The values were significantly different across the batches (p<0.05). Hardness values obtained varied significantly (p<0.05) and were between 5 and 12 KgF which imply that most of the tablet batches are harder than normal depending on the proportion of the polymer used. All the batches exhibited friability within the standard limit without significant difference in values (p>0.05), indicating that tablet formulated with the experimental binders would not undergo surface abrasion. All the formulations exhibited zero order kinetics except batches DPP-10 and DPP-15 which showed Higuchi mechanism. Formulation batches DRA-05 and DRA-10 showed maximum drug release of 98% and 95% respectively after 6 h. A prolonged drug release was observed on increasing polymer ratio. Significantly higher release rates (p<0.05) were observed in the tablets formulated with PVP than those containing R. africana gum. All the batches followed non-fickian diffusion release mechanism.Conclusion: From the study, purified R. africana hydrocolloid generally appeared to perform better than PVP as sustained release agent.

Antibacterial potency and fluoride release of a glass ionomer restorative material containing different concentrations of natural and chemical products: An in-vitro comparative study.

BackgroundThis study investigated the antibacterial efficacy against Streptococcus mutans and fluoride release of a conventional glass ionomer (GI) contained natural and chemical agents.Material and MethodsTwo hundred and ten GI specimens were divided into ten groups (n=21) according to the concentrations of the additives as; Propolis extract containing GI (Groups 1, 2, 3) with concentrations of 0.25%, 0.75% and 1.25% respectively, Miswak extract containing GI (Groups 4, 5, 6) and Chlorhexidine containing GI (Groups 7, 8, 9) with the same concentrations. The prepared specimens were subjected to antimicrobial activity by well diffusion, bacterial adherence, and fluoride release (from 2 to 72 hours) assessments.ResultsA higher statistically significant antibacterial activity was found in (Groups 2, 3) compared to (Groups 8, 9), while (Groups 1, 4, 5, 6, 7, 10) no antibacterial efficacy was reported. For (Groups 2, 3) had a higher statistically significant anti-adherence effect compared to the other tested groups. Enhanced ascending increase in fluoride release was observed for (Groups 3, 4) compared to (GI).ConclusionsThe increased concentration of propolis extract had a synergistic effect on the antimicrobial activity of the tested GI. Additive concentrations of 0.25% Miswak and 1.25% propolis could enhance the fluoride-releasing ability of the tested GI. Key words:Propolis, miswak, chlorhexidine, glass ionomer, fluoride.