Release Rate Of Aspirin Research Articles

Drug release studies of titanium-based polyethylene glycol coating as a multifunctional substrate

Thrombosis is the fundamental basis of a catastrophe of cardiovascular and other blood-reaching biomedical gadgets. Drug-eluting inserts for the nearby conveyance of anti-infection agents at clinical locales are believed to be promising in averting cardiovascular diseases. Titanium and its compositions have been generally utilized for blood-reaching biomedical devices because of its excellent biocompatibility; however, their blood compatibility should be improved. In this present study, titanium surface was modified with sodium hydroxide (NaOH) which generate hydroxyl group (–OH) groups thereby facilitating encapsulation of aspirin (200 mg) accompanied by the coating of various percentage (0.5%,1%,2%, 2.5% and 3% w/v) of polyethylene glycol (PEG) (MW-20,000). The drug release amount could be managed by the aspirin loading quantity and the PEG covering thickness. The measure of aspirin delivered in phosphate buffer solution (pH = 7.4) was resolved by utilizing a UV–Vis spectrophotometer. Aspirin was released continuously till 8 h for 0.5% to 2.5% PEG coating whereas for 2.5% and 3% PEG coating it has been released till 9 h. The aspirin release rate from the titanium substrates was performed by fitting the data to the Ritger–Peppas equation. The diffusional type n for a lower percentage of PEG coating indicates non-fickian transport because of swelling of the PEG layer whereas a higher percentage of PEG coating indicates the super case II transport mechanism in aspirin discharge. Therefore, the developed Ti-based substrates have the potential to elute drugs continuously thereby making them suitable for cardiovascular implants.

Tailoring surface properties of polyethylene terephthalate by atmospheric pressure plasma jet for grafting biomaterials

Tailoring surface hydrophilicity on polyethylene terephthalate (PET) by a radio frequency (RF) atmospheric pressure plasma jet (APPJ) for grafting biomaterials was investigated in this study. Two thermally responsive biomaterials of hydrophilic non-ionic surfactant of polyoxyethylene polymer and hydroxypropyl cellulose were used, while hydroxyethylmethacrylate (HEMA) was applied as the carrier for drug release. As applying the RF power in an APPJ system, PET substrates represented a tendency from an originally hydrophobic surface to a hydrophilic one, while apparent damaged areas were observed as the RF power exceeded 200 W. APPJ-induced polar functional groups onto PET surface without serious etching were most likely to improve the surface hydrophilicity for further grafting biomaterials. The grafted polyoxyethylene polymer on APPJ-treated PET substrates exhibited a surface change from opaque into transparent as the ambient temperature exceeded lower critical solution temperature of 37°C, while hydroxypropyl cellulose displayed a change from transparent into milky white as the temperature over 55°C. For the drug release behavior of aspirin on APPJ-treated PET substrates, the cumulative release rate of aspirin entrapped substrate for 3 h was 22%. Our results suggest that tailoring surface hydrophilicity of PET substrates without surface etching by 100W-APPJ process possessed a higher surface energy with a higher polar interaction, resulting in a good bonding with the grafted biomaterials.

Effect of Quaternary Ammonium Carboxymethylchitosan on Release Rate In-vitro of Aspirin Sustained-release Matrix Tablets.

The aim of this study was to develop a derivative of chitosan as pharmaceutical excipient used in sustained-release matrix tablets of poorly soluble drugs. A water-soluble quaternary ammonium carboxymethylchitosan was synthesized by a two-step reaction with carboxymethylchitosan (CMCTS), decylalkyl dimethyl ammonium and epichlorohydrin. The elemental analysis showed that the target product with 10.27% of the maximum grafting degree was obtained. To assess the preliminary safety of this biopolymer, cell toxicity assay was employed. In order to further investigate quaternary ammonium carboxymethylchitosan application as pharmaceutical excipient, aspirin was chosen as model drug. The effect of quaternary ammonium CMCTS on aspirin release rate from sustained-release matrix tablets was examined by in-vitro dissolution experiments. The results showed that this biopolymer had a great potential in increasing the dissolution of poorly soluble drug. With the addition of CMCTS-CEDA, the final cumulative release rate of drug rose up to 90%. After 12 h, at the grade of 10, 20 and 50 cps, the drug release rate increased from 58.1 to 90.7%, from 64.1 to 93.9%, from 69.3 to 96.1%, respectively. At the same time, aspirin release rate from sustainedrelease model was found to be related to the amount of quaternary ammonium CMCTS employed. With the increase of CMCTS-CEDA content, the accumulated release rate increased from 69.1% to 86.7%. The mechanism of aspirin release from sustained-release matrix tablets was also preliminary studied to be Fick diffusion. These data demonstrated that the chitosan derivative has positive effect on drug release from sustained-release matrix tablets.

Preparation, characterization, and release behavior of aspirin‐loaded poly(2‐hydroxyethyl acrylate)/silica hydrogels

Poly(2-hydroxyethyl acrylate) (PHEA) is a polymer hydrogel that can be used as a biomaterial. In this study, PHEA/silica composites containing aspirin as a model drug were prepared, and their drug release behaviors were tested. 2-Hydroxyethyl acrylate (HEA) was first copolymerized with 3-(trimethoxysilyl) propyl methacrylate (MSMA) in the presence of ammonium persulphate and then condensed with silicic acid oligomer. The composites were characterized with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). In addition, water uptake and matrix erosion of PHEA/silica of different weight ratios were also investigated. The results indicated that the silica particles were well dispersed in PHEA hydrogels. The in vitro drug release test revealed that the release rate of aspirin decreased with the increasing content of silica. The drug release behaviors were analyzed by employing the power law, which showed that the release profiles were governed either by Case II diffusion or by anomalous diffusion. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay of rabbit chondrocytes revealed that adding silica can improve the biocompatibility of PHEA to some extent.

The effect of carboxymethyl chitin on sustained drug release of aspirin tablet

Carboxymethyl chitin (CM-chitin) was prepared at room temperature and characterized using 1H NMR, FTIR and elemental analysis methods. The prepared CM-chitin was then used as a hydrophilic matrix for the preparation of the aspirin sustained release tablets via the wet granulation technique. The aspirin release profiles of the prepared tablets in a simulated gastric fluid and simulated intestinal fluid, respectively, were studied with the rotating-basket dissolution method. The results showed that the aspirin release rate in simulated gastric fluid was lower than that in simulated intestinal fluid. Thus, CM-chitin proved to be a pH-sensitive hydrophilic matrix.

Bimodal Mesoporous Silicas Functionalized with Different Level and Species of the Amino Groups for Adsorption and Controlled Release of Aspirin

The synthesis of modified bimodal mesoporous materials (BMMs) with a small pore size of around 2.9 nm and a large pore size of about 20 nm has been performed via post-grafting methods. To study the application of functionalized BMMs in drug delivery, loading and releasing profiles using aspirin as model drug were carried out. XRD, SEM, TEM, N2 adsorption, FT-IR, 29Si-NMR, TG and UV-Vis spectroscopy were used to characterize the related samples. The post-grafting modification was performed through the weak chemical interaction or hydrogen bonding in between OH groups of the mesopore surface and 3-aminopropyltriethoxysilane (N-TES) or 3-(2-aminoethylamino) propyItrimethoxysilane (NN-TES). The results showed that N-TES groups with different amount and NN-TES groups were successfully incorporated onto the mesopore surface. Subsequently, the controlled aspirin delivery properties from the resulting modified BMMs were investigated in detail. The aspirin adsorption experiments indicated that the adsorption capacities of modified BMMs were improved with the increasing amount of N-TES groups, while the NN-TES functionalized samples showed higher adsorption capacity than N-TES modified samples with the same ratio of modification. The most reason is that the interaction between the NN-TES groups and aspirin molecules is stronger than that between the N-TES groups and aspirin molecules. The in vitro tests exhibited that aspirin release behaviors mainly depended on the variation of the amount and species of the functional groups in mesoporous carries. According to the Korsmeyer-Peppas model, it is found that the kinetic release constant k reduced with the increase amount of the amino groups on the mesopore surface of modified BMMs, suggesting that the aspirin release rate from the pores of BMMs was influenced directly by organic groups on the surface. The release exponent n of all the situations were above 0.5, indicating the drug release mechanism followed a non-Fickian model that was diffusion based. Therefore, this type of materials described in this paper is of strong potential for the controlled drug release applications.

Structure and Release Behavior of PMMA/Silica Composite Drug Delivery System

The preparation, characterization, and in vitro release of aspirin from polymethylmethacrylate (PMMA)/silica composites prepared via a sol-gel route are reported. The in vitro drug release test revealed that the release rate of aspirin in PBS increased with the silica content in the composites; on the contrary, the increase of the content of 3-(trimethoxysilyl) propyl methacrylate (MSMA), a coupling agent, decreased the drug release rate. The drug release rate/composite structure relationship was studied using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and swelling ratio (SR) measurement. The results indicated that the interface between polymer matrix and inorganic fillers has significant influence on the drug release behavior of the composite materials. In addition, models of mass transfer based on Fickian diffusion law at constant temperature and pressure were employed to analyze the results of the in vitro drug release experiments. The drug release behaviors of the composite samples fitted well with the Fickian diffusion model. The values of k, which is in direct proportion to drug release rate, increased with the increasing content of silica while decreased with that of MSMA in the composite samples.

APPLICATION OF GELATIN FOR ENCAPSULATING ASPIRIN INTO ETHYL CELLULOSE MICROCAPSULE IN AN O/W EMULSION

The application of gelatin protective colloid for microencapsulating aspirin in ethylcellulose was demonstrated using an oil-in-water emulsification/solvent evaporation technique. The gelatin concentration, alcohol co-solvent amount, and ethylcellulose viscosity were investigated by analyzing the recovered weight, particle size distribution, drug loading efficiency, aspirin release rate, surface characteristics, and release kinetics. Results showed that recovery increased with greater concentrations of gelatin (up to 1%). Adding co-solvent (ethanol) also changed the microcapsule particle size distribution. Higher recovery and release rates were obtained when the ethanol content in polymer solvent was at 25% and the viscosity of ethylcellulose was low (45cps). The release rate followed Higuchi matrix release kinetics, suggesting a monolithic system with aspirin uniformly distributed over the microcapsule.

Encapsulating aspirin into a surfactant-free ethyl cellulose microsphere using non-toxic solvents by emulsion solvent-evaporation technique

Microencapsulation of aspirin in ethylcellulose was studied in a surfactant-free, water-in-oil type of emulsification/solvent evaporation process using non-toxic solvents. Ethanol was used as the dispersed phase and soybean oil as the continuous phase. The recovered weight, particle size distribution, aspirin loading efficiency, and the aspirin release rate of microspheres were analysed. The addition of a small amount of non-solvent (water) prior to the emulsification was found to have a significant impact on the microencapsulation process. Adding non-solvent increases the recovered weight and the size of the microspheres. The addition of non-solvent also markedly changes the microsphere characteristics, resulting in a coarser surface and an increased release rate. Increasing the emulsification evaporation temperature increases the size of the microsphere, but reduces the recovered weight and loading efficiency. The release rate follows a first-order kinetics and Higuchi matrix kinetics at low concentrations of non-solvent, suggesting a monolithic system with aspirin uniformly distributed in the microsphere.

An enhanced process for encapsulating aspirin in ethyl cellulose microcapsules by solvent evaporation in an O/W emulsion

An enhanced process for microencapsulating aspirin in ethylcellulose was demonstrated using an oil-in-water emulsification/solvent evaporation technique. Methylene chloride (CH2Cl2) was used as the dispersed medium and water as the dispersing medium. The recovered weight, particle size distribution, aspirin loading efficiency, and the aspirin release rate of microcapsules were analysed. The addition of appropriate amounts of non-solvent (n-heptane) prior to the emulsification increases the recovered weight, but decreases the size of the formed microcapsules. The addition of non-solvent also changes the microcapsule characteristics, resulting in a coarser surface and an increased release rate. Increasing the polymer (ethylcellulose) concentration in the dispersed phase increases the size of the microcapsules, the recovered weight, and loading efficiency, but decreases the release rate. The release rate follows first-order kinetics during the first 12h, suggesting a monolithic system with aspirin uniformly distributed in the microcapsule.

Effects of Hydrophilic Excipients and Compression Pressure on Physical Properties and Release Behavior of Aspirin-Tableted Microcapsules

Aspirin ethylcellulose microcapsules were tableted by compression with or without excipients (lactose or polyvinylpyrrolidone [PVP]). The effects of the amount of the excipients and microcapsule size on the crushing strength and release rate of aspirin from tableted microcapsules were investigated. Tablets without excipients had a crushing strength that was independent of the applied pressure and microcapsule size. An increase in compression pressure from 15 to 60 MPa resulted in an increase in the crushing strength of tablets containing 20% or 40% w/w lactose, but the reverse results were obtained for the tableted microcapsules containing 20% or 40% w/w PVP. Results showed that the release rate of aspirin from microcapsules containing lactose or PVP was independent of the compression pressure with the exception of tablets containing 40% w/w lactose. In vitro release profiles of aspirin from tableted microcapsules containing lactose or PVP showed that increasing the concentration of the excipients resulted in an increase in the release rate of aspirin. Values of n were changed by the compression pressure and the added excipients.

Effect of tablet integrity on the dissolution rate of sustained-release preparations.

The objective of this study was to evaluate the effect of tablet integrity on the dissolution rate. The model drug used for this study was aspirin. A dissolution study was performed with three commercially-available aspirin tablets (ZORprin, Bayer 8-h aspirin and Bayer aspirin), two of which were sustained-release tablets. For ZORprin, the average dissolution data indicated that the in vitro release rate of aspirin was consistent with the intended design of the sustained-release wax matrix tablets only when the tablets were intact. The split tablets showed a consistently higher release profile over time, with a 50% higher release at 6 h. However, the Bayer 8-h aspirin and plain aspirin tablet data showed that tablet integrity had no significant impact on the dissolution rate, because the intact and split tablets showed similar drug release profiles over time. In conclusion, care should be taken to administer sustained-release tablets, avoiding any breaking or crushing of the tablets unless this is directed by the manufacturer.

Biopharmaceutical characterisation of a low-dose (75 mg) controlled-release aspirin formulation.

The release of aspirin from a 75 mg controlled-release formulation, designed to inhibit maximally thromboxane A2 production while sparing stimulated prostacyclin biosynthesis, was characterised in healthy subjects. The calculated in vivo release rate of aspirin matched the design goal of approximately 10 mg h(-1). The C(max) of aspirin associated with the controlled-release formulation was lowered 15-fold relative to a solution formulation of the same dose. The bioavailability of aspirin (based on salicylate concentrations) from the controlled-release formulation was approximately 90% relative to the solution, and drug release was not affected by co-administration of a standard breakfast.

Synthesis of Biocompatible Polymers with Aspirin-Moieties for Aspirin Delivery

Polyacrylate and polyhydroxylate polymers with aspirin moieties were prepared. The acrylate polymers were obtained by the synthesis and poly merization of several new monomers; β-(acetylsalicylyloxy)ethy methacrylate, β-(acetylsalicylyloxy)propyl methacrylate, β-(acetylsalicylyloxy)ethy acrylate, β-hydroxy-γ-(acetylsalicylyloxy)ethyl methacrylate and β-hydroxy-γ-(acetylsali cylyloxy)propyl methacrylate. The second series of biocompatible polymers with aspirin moieties was prepared by reacting the hydroxyl group of poly(vinyl alcohol) and poly(allyl alcohol) with 1-(acetylsalicylyl)benzotriazole. Both the homogeneous and heterogeneous hydrolysis of eight biocompatible polymers and copolymer with aspirin moieties were investigated in acidic or alkaline medium at 37 ° C or 60 °C, respectively. The main hydrolysis product was aspi rin with minor amounts of salicylic acid. The release rates of aspirin and sali cylic acid were related to the hydrolysis temperature, and the length of side chain. The release rate of aspirin and salicylic acid from poly[1-(acetylsalicylyl oxy)ethyl methacrylate-co-methacrylic acid] is markedly dependent on polymer composition and the pH value of hydrolysis medium.

The effect of suspending agents on the release of aspirin from aqueous suspensions in vitro

The effect of various suspending agents on the release of aspirin from aqueous suspensions in vitro was studied using a flask-stirrer method and a dialysis method. The latter proved to be more sensitive in detecting changes in the rate of release. The existence of a rank order relationship between kinetic parameters that described the release rate of aspirin and the viscosities of the suspension media was demonstrated.

In vivo Drug Release Rate from Hard Gelatin Capsules

Serum salicylate levels were utilized to evaluate the relative release rate of aspirin from a commercial aspirin tablet and from a hard gelatin capsule. Although a few subjects obtained rapid release from the capsules, the majority had an appreciable delay relative to tablets. The population distribution of levels is markedly different between capsules and tablets at the times studied. The median delay for significant levels is approximately 15 min. Serum salicylate levels were utilized to evaluate the relative release rate of aspirin from a commercial aspirin tablet and from a hard gelatin capsule. Although a few subjects obtained rapid release from the capsules, the majority had an appreciable delay relative to tablets. The population distribution of levels is markedly different between capsules and tablets at the times studied. The median delay for significant levels is approximately 15 min.