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PubMed2001

Acrylic resins as rate-controlling membranes in novel formulation of a nine-day 17beta-estradiol transdermal delivery system: in vitro and release modifier effect evaluation.

The feasibility of transdermal controlled delivery system of 17beta-estradiol was investigated by conducting in vitro release studies. Several new 17beta-estradiol unilaminate adhesive devices capable of releasing 17beta-estradiol in a controlled fashion over a 24-h, 36-h, 96-h, 104-h, 168-h, and 216-h period have been developed using acrylic resins (Eudragits E100, RSPO, and RLPO) as adhesive and rate-controlling polymers. The in vitro release profiles of 17beta-estradiol from various TDS unilaminate devices were characterized in a new developed dissolution tester vessel (total volume 200 ml), using a new paddle. The release of drug from different formulations was measured by a sensitive high-performance liquid chromatographic (HPLC) method. The release of drug from all prepared adhesive devices seems to obey zero-order kinetics (r > 0.98). The effect of two different plasticizers (acetyltriburyl citrate [ATBC] and triethyl citrate [TEC]) on the release patterns of 17beta-estradiol from TDS formulations was studied, and they were almost identical. The effect of two different release modifiers, propylene glycol (PG) and myristic acid (MA), on the release pattern of 17beta-estradiol from prepared unilaminate devices was evaluated. It was shown that the use of these release modifiers significantly increased the release of 17beta-estradiol from a TDS unilaminate patch. Furthermore, these data clearly demonstrated that the acrylic resins are suitable polymers for the preparation of 17beta-estradiol TDS adhesive devices.

Acrylic Resins↗

PubMed2003

Acrylate-based transdermal therapeutic system of nitrendipine.

The objective of the present research investigation was to fabricate an acrylate-based transdermal therapeutic system (TTS) of nitrendipine, which could deliver drug at maximum input rate so as to deliver drug in minimum patch size. Transdermal patches were fabricated using synthesized acrylate pressure-sensitive adhesives (PSAs): PSA1, PSA2, and commercially available PSA3 and PSA4 using d-limonene as permeation enhancer. Effect of concentration of d-limonene on permeation kinetics of nitrendipine in PSAs was studied. Fabricated TTS in mentioned PSAs were evaluated for in-vitro release and permeation kinetics through guinea-pig skin. Cumulative release of drug in PSA1, PSA2, PSA3, and PSA4 was observed to be 45%, 40%, 25%, and 25%, respectively, upto 24 hr. Flux of drug through guinea-pig skin calculated at 48 hr in PSA1, PSA2, PSA3, and PSA4, with and without d-limonene, was observed to be 0.346+/-0.10, 0.435+/-0.17, 0.410+/-0.17, and 0.162+/-0.06, and 0.625+/-0.19, 1.161+/-0.46, 0.506+/-0.17, and 0.520+/-0.18 (microg/cm2/hr), respectively. The TTS in PSA2 showed comparatively high flux and could deliver drug at high input rate through transdermal route. PSA2 was found to have good rate-controlling property and could be successfully employed in transdermal delivery of nitrendipine.

Acrylates↗

PubMed2003

Acrylic matrix type nicotine transdermal patches: in vitro evaluations and batch-to-batch uniformity.

Nicotine transdermal patches (NTPs) were fabricated using an acrylic pressure sensitive adhesive emulsion to form a transparent matrix film. An automated thin layer chromatography (TLC) plate scraper was used to control the thickness of the cast nicotine matrix film. The in vitro release behavior and permeation of nicotine across abdominal human epidermis (HE) from the NTPs was studied using United States Pharmacopeia (USP) dissolution apparatus 5 (paddle over disk) and modified Franz-diffusion cell, respectively. The release of nicotine from the NTPs showed a good linear correlation with the square root of time (R2 > 0.99). This indicated a matrix diffusion controlled-release mechanism. The surface morphology of the matrix of the NTP was uniform and nonporous before and after release, indicating that the dried adhesive nicotine matrix was a homogeneous single-phase film. Neither the nicotine content in the range 4.70-8.41% w/w nor the film thicknesses of the NTPs affected the apparent diffusion coefficient of nicotine in the acrylic matrix. A good relationship between the amount of nicotine permeated across the HE and the square root of time was also observed with R2 > 0.98. This study also showed that the NTPs provided a good delivery system with more than 65% of the nicotine delivery being controlled by the device. Moreover, the release of nicotine from six production batches met the criteria of USP 24. This finding presented a good potential of this method for upscaling to industrial manufacturing.

Acrylic Resins↗

PubMed2001

Influence of film additives on stabilizing drug release rates from pellets coated with acrylic polymers.

The objective of this study was to investigate the influence of talc and triethyl citrate (TEC) on stabilizing the drug release rates following curing and storage at elevated temperature of pellets coated with an aqueous acrylic polymeric dispersion. Core pellets containing anhydrous theophylline (20%), microcrystalline cellulose, and polyvinylpyrrolidone were prepared by extrusion-spheronization. The aqueous dispersions were prepared by adding up to 30% TEC as a plasticizer and talc up to 200% as an antiadherent to a mixture of Eudragit RS 30D/RL 30D (95:5). The theophylline pellets were coated in a fluidized-bed coating unit and then cured at elevated temperatures. Theophylline pellets were successfully coated with the Eudragit dispersions that contained up to 200% talc, based on the dry polymer weight, and the coating efficiency was greater than 93%. Our results demonstrated that the polymer, which was plasticized by TEC, was able to function as a film-forming agent for dispersions containing high levels of talc. No sticking of the coated pellets was observed during the coating process or during the curing or equilibrating phase, even with high levels of TEC in the film. The dissolution rate of theophylline from the coated pellets was delayed when the film coating dispersion contained high levels of talc. Additionally, the stability of the drug release profiles from the coated pellets after storage was significantly improved. Furthermore, a modified dissolution testing used to simulate mechanical stresses that may be encountered in vivo showed the film coated pellets would have sufficient strength. The results of this study demonstrated that high levels of film additives in the acrylic dispersion contributed to the stabilization of the drug release rates as well as the reproducibility of the coating process.

Acrylic Resins↗

PubMed1986

Comparative in-vitro activity of antibiotics incorporated in acrylic bone cement.

We compared the persistence of antibacterial activity around antibiotic-impregnated acrylic bone cement discs which were serially transferred on seeded agar plates. On plates inoculated with Staphylococcus aureus ATCC 25923, CMW1 discs containing 2.5% by dry weight of cephalothin, coumermycin or fusidic acid (as diethanolamine fusidate) produced zones of inhibition for four to eight weeks when transferred daily. In contrast, ceftriaxone, cotrimoxazole, rifampicin and vancomycin ceased to be inhibitory within a week. Discs made of 'Palacos-R with Garamycin,' which contains gentamicin 1.25%, had an intermediate duration of activity. When Escherichia coli ATCC 25922 was used as the test organism, ceftriaxone and 'Palacos-R with Garamycin' showed activity for almost three weeks, cephalothin and cotrimoxazole were briefly inhibitory and the remainder not at all. When discs were transferred each week instead of daily, the ranking of antibiotics was similar but antibacterial activity persisted for longer. A combination of gentamicin plus fusidic acid in CMW1 was active for a much shorter time than either fusidic acid alone or 'Palacos-R with Garamycin'. We conclude that coumermycin is a promising new agent for incorporation in acrylic cement.

Acrylates↗

PubMed2004

Ethyl acrylate risk assessment with a hybrid computational fluid dynamics and physiologically based nasal dosimetry model.

Cytotoxicity in the nasal epithelium is frequently observed in rodents exposed to volatile organic acids and esters by inhalation. An interspecies, hybrid computational fluid dynamics and physiologically based pharmacokinetic (CFD-PBPK) dosimetry model for inhaled ethyl acrylate (EA) is available for estimating internal dose measures for EA, its metabolite acrylic acid (AA), and EA-mediated reductions in tissue glutathione (GSH). Nasal tissue concentrations of AA were previously used as the dose metric for a chronic Reference Concentration (RfC) calculation with this compound. However, EA was more toxic than expected, based on calculated tissue AA concentrations. Unlike AA, EA causes depletion of tissue GSH. We have developed an RfC for EA using tissue GSH depletion in the olfactory epithelium as the primary measure of nasal tissue dose. The hybrid CFD-PBPK model was refined to improve the accuracy of simulations for GSH in rat olfactory tissues. This refined model was used to determine the concentration for continuous human exposures to EA predicted to reduce nasal GSH levels to the same extent as seen in rats exposed to EA at the no-observed-effect level (NOEL). Importantly, AA concentrations in the human nasal olfactory epithelium at the proposed chronic RfC were predicted to be lower than the AA concentrations estimated in the rat at the NOEL. Thus, a chronic RfC based on maintaining GSH in the human nasal olfactory epithelium at levels equivalent to the rat NOEL would also provide an adequate margin of safety with respect to AA concentrations in nasal tissues.

Acrylates↗

PubMed1993

Acrylic splints for dental alignment in complex facial injuries.

Twenty-four patients with complex facial injuries were managed by wide subperiosteal exposure, precise anatomical reduction, rigid internal fixation, and immediate bone grafting when indicated, in conjunction with dental impressions, model surgery, and fabrication of dental splints to establish proper preinjury occlusion. The study population consisted of 18 men and 6 women, whose ages ranged from 18 to 49 years (mean, 30.7 yr) at the time of injury. High velocity motor vehicle accidents were responsible for facial injuries in 18 patients, gunshot wounds in 2, low velocity blunt trauma in 3, and falls in 1. All facial fractures involved the occlusion, and unstable and/or comminuted palatal/maxillary and mandibular fractures, often with edentulous segments, were the major indications for fabrication of acrylic splints. Depending on the nature of the fracture pattern, model surgery was performed on the maxillary and/or mandibular models and segmented along fracture lines. These fragments were then repositioned according to dental wear facets and preinjury occlusion. When possible, preinjury occlusal records were obtained before splint fabrication. Models were mounted on a Galetti articulator and palatal, lingual, and/or occlusal splints were fabricated. Edentulous segments were compensated for by local buildup of the splints to produce an occlusal stop. Arch bars were fixed directly to the splint with acrylic. Twenty-six splints were used in the 24 patients to establish proper occlusal relationships before internal fixation of fractures. The types of splints were palatal (n = 8), palatal-occlusal (n = 6), lingual (n = 8), lingual-occlusal (n = 1), and occlusal (n = 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylic Resins↗

PubMed1990

Rat sciatic nerve regeneration within an acrylic semipermeable tube and comparison with a silicone impermeable material.

Sectioned rat sciatic nerves were placed in tubes to study the regrowth of injured nerve processes. First, we characterized quantitatively the regeneration of myelinated fibers at different levels of an acrylic semipermeable tube, from two to 27 weeks postoperatively. From the fifth week, myelinated fiber counts at mid-tube level were equal to the value of an intact nerve, but at the distal part the number of fibers exceeded both mid-tube level and unsectioned nerve values. At the proximal part of the tube an important fiber disorganization was observed. Second, we have compared acrylic semipermeable and totally impermeable silicone tubes at four and 27 weeks postoperatively. In terms of the number of myelinated fibers and the surface of the endoneurium at the mid-tube level, the most effective tube was the impermeable one. This study points out the importance of the tube wall permeability in nerve regeneration.

Acrylates↗

PubMed2004

Fatal pulmonary complications after arterial embolization with 40-120- micro m tris-acryl gelatin microspheres.

Hepatic arterial embolization is a recognized method of treating primary malignancies and some secondary hepatic malignancies. Particle embolization alone has been shown to be safe and effective and is routinely performed for hypervascular tumors. Tris-acryl gelatin microspheres have been widely acclaimed for their ease of delivery and uniform size, allowing for accurate targeting of particular end arteries. There have been three deaths at the author's institution related to respiratory compromise since the 40-120- micro m particles became available 31 months ago. These complications were never observed with larger tris-acryl gelatin microspheres or polyvinyl alcohol particles. This is an unusual and serious complication of which interventionalists performing embolotherapy need to be aware.

Acrylates↗

PubMed2005

Acrylates induced rhinitis and contact dermatitis.

Acrylates are a well-known cause of occupational contact dermatitis due to its widespread use in several settings such as dentistry, orthopaedic surgery, graphic industry and cosmetics. We describe the case of a manicurist who developed occupational rhinitis and allergic contact dermatitis induced by the application of acrylic-sculptured nails.

Acrylates↗

PubMed1978

Skin problems associated with multifunctional acrylic monomers in ultraviolet curing inks.

Fifteen cases of contact dermatitis and three of irritant contact conjunctivitis due to multifunctional acrylic monomers in printing inks are described. Seven with dermatitis were sensitized to pentaerythritol triacrylate but evidenced no cross-reactivity to methyl methacrylate. The other eight cases of dermatitis were irritant. Pentaerythritol triacrylate has been shown experimentally to be a cutaneous sensitizer for guinea-pigs and man. Multi-functional acrylates should be handled with minimal skin contact, to avoid cutaneous problems.

Acrylates↗

PubMed1981

Addition of fluoride compounds to acrylic resin plates: bending strength and fluoride release.

The effect of incorporated CaF2 (2.04%), NaF (2.27%) and amine fluoride (0.71%) in acrylic resin plates, on bending strength and fluoride release by rinsing and immersion in synthetic saliva, was determined. Bending strength was reduced by 6.7, 9.5 and 20% respectively. The most elevated release of fluoride from the NaF containing--and the most protracted from the CaF2 containing--plates may be related to the solubilities of the compounds. It appears that the organic molecule of the AmF compound affects the strength of the acrylic plates most significantly. The F- concentrations released in the in vitro rinsing experiment may be presumed to occur in vivo at some higher level due to the larger size of dental appliances.

Acrylic Resins↗

PubMed1992

Effect of metal strengthener's surface roughness on fracture resistance of acrylic denture base material.

The aim of this study was to clarify the effect of the surface roughness of various metal wires on the fracture resistance of the acrylic test specimens. The number of test groups compared were 16, and there were 30 test specimens in each group. The investigation showed that the surface roughening of the metal wires used to reinforce acrylic resin denture base material increased the fracture resistance of the test specimens. The best results were achieved by sandblasting. The differences in resistance were also statistically significant.

Acrylic Resins↗

PubMed1993

The release of chlorhexidine from modified dental acrylic resin.

A method for the incorporation of chlorhexidine into acrylic resin using monomer together with the pattern of release of chlorhexidine from treated resin into water at 37 degrees C is described. Release from polished and unpolished resin, and from acrylic prepared by short-curing and dry-curing processes are investigated. The pattern of release in all cases was of an exponential nature, showing a rapid release within the first 10 days becoming almost constant at a level of 0.4-1.5 micrograms cm-2 at about 20 days. Release was still evident at the end of the test period in all cases. Release of chlorhexidine into water from the short-cure specimens was accompanied by release of monomer, evident from the odour of the test solutions, indicating that polymerization was not complete.

Acrylic Resins↗

PubMed1994

Surface texture evaluation of glass ionomer restorative materials polished utilizing poly(acrylic acid) gel.

This study evaluated the surface texture of three different glass ionomer restorative materials and a composite resin, polished by a new method using poly(acrylic acid) gel. Conventional polishing methods and finishing agents were compared to the proposed new procedure. Evaluations were carried out employing three techniques: profilometry, scanning electron microscopy and microhardness testing. The use of a poly(acrylic acid) gel with polishing discs gave significantly better results, and is therefore recommended for clinical applications.

Acrylic Resins↗

PubMed1996

Colour changes in acrylic teeth--comparison of an objective and subjective method.

Colour changes in four currently used brands of acrylic dental teeth were measured objectively and assessed subjectively following the application of heat, acrylic monomer and light. The data indicated that no clear correlation existed between the results of visual inspection and opto-electronic measurements. It is suggested that visual assessment is an unreliable method of detecting colour change, and an objective colorimetric method is therefore recommended.

Acrylic Resins↗

PubMed2004

Effect of metal strengthener length on stress distribution in acrylic denture bases: a finite element study.

This study investigated the influence of metal strengthener length on stress created in acrylic denture bases in relation to location of the vertical support to the dentures. Finite element analysis was conducted to calculate stress generated in the straps of 2 mm-thickness and 18 mm-width that were reinforced with metal strengtheners of five different lengths. A vertical biting force of 60 N was directed on one end of each strap, while the other end was fixed. Vertical movements were restricted at one of the three support locations between the centre of the strap and the loading site. When the straps were vertically supported near the loading site, greater maximum tensile stresses were seen in the straps with relatively short strengtheners than those shown in the straps with longer strengtheners. The metal strengtheners with sufficient length may provide a preventive denture design against the acrylic fractures.

Acrylic Resins↗

PubMed2004

Reduction of shrinkage on heat-activated acrylic denture base resin obtaining gradual cooling after processing.

Heat-activated acrylic denture base resin is widely used for its many good attributes, although it does show polymerization shrinkage. Although several processing methods have been developed for the purpose of minimizing polymerization shrinkage, some warping after processing is inevitable. The purpose of this study was to examine the development of residual stress relaxation in resin denture base samples in the region where shrinkage was restricted, in order to clarify how cooling variations in the stone mould influenced the shrinkage. Flat, dumbbell-shaped specimens were used. Thermocouples and strain gauges were embedded in the resin for measuring temperature and strain during the dough-stage of resin packing. To clarify stress relaxation in the stone mould, specimens were removed from the stone mould by de-flasking 4 h after the start of cooling at room temperature (control), and 12 and 24 h from the start of gradual cooling in a water bath. The strain differences between before and after removing from the stone mould for the control, and 12- and 24-h experimental groups were 1793, 1354 and 1093 mu epsilon, respectively. Our results suggest that a gradual cooling course for 12 h or more after processing a heat-activated acrylic denture base is effective for lessening deformation of the prosthesis.

Acrylic Resins↗