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1.
J Strength Cond Res ; 38(6): 1072-1081, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38489587

RESUMEN

ABSTRACT: Hughes, W, Healy, R, Lyons, M, Higginbotham, C, Lane, A, and Beattie, K. The strength characteristics of elite and subelite female Gaelic football players. J Strength Cond Res 38(6): 1072-1081, 2024-There is currently an underrepresentation of sports science research focused on the female athlete, specifically in the context of Gaelic football. The aims of this study are to (a) compare the strength characteristics of elite and subelite players and (b) establish normative-based values and percentile scores for the strength characteristics of female Gaelic football players. Ninety-two female Gaelic football players were recruited for this study and subsequently categorized as elite (intercounty n = 30, age; 25.1 ± 5.3 years, stature; 1.69 ± 0.06 m, mass; 69.5 ± 5.9 kg) or subelite (club n = 62, age; 25.4 ± 6.8 years, stature; 1.66 ± 0.06 m, mass; 65.1 ± 8.9 kg). The physical strength characteristics of the subjects were assessed through the isometric midthigh pull (IMTP), countermovement jump (CMJ), and 10-5 repeated jump test. Statistically significant differences were found in the physical strength characteristics between the groups with elite players demonstrating greater peak force (large effect), relative peak force (moderate effect), and reactive strength index (large effect). Statistically significant differences were also observed for key CMJ phase characteristics with elite players producing greater RSI mod (moderate effect), jump height (large effect), and propulsion peak power (large effect) than subelite players. This study demonstrated that there are moderate to large differences between playing standards with elite players displaying superior reactive-, explosive-, and maximal-strength than their subelite counterparts. The strength characteristics evaluated in this study may be used in conjunction with other performance indices to distinguish between elite and subelite playing standards in female Gaelic football players.


Asunto(s)
Fuerza Muscular , Humanos , Femenino , Fuerza Muscular/fisiología , Adulto Joven , Adulto , Rendimiento Atlético/fisiología , Atletas , Prueba de Esfuerzo , Músculo Esquelético/fisiología
2.
Polymers (Basel) ; 16(16)2024 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-39204558

RESUMEN

This work looks at the effects of a varying concentration, soak time, pH and temperature on the sorption of tetraammineplatinum(II) chloride (Pt-Ammine) in Nafion-117 films in the context of the electroless plating of ionic polymer-metal composites (IPMCs). Sorption is characterised by atomic absorption spectroscopy. A definitive screening design carried out determined all four factors to be significant for further analysis using response surface modelling. A duplicated central composite design (CCD) was utilised to characterise how the four factors affect the sorption amount and efficiency. Regression models for both responses were of poor fit. Nevertheless, key insights were obtained on the effects of the process parameters on sorption behaviour. The results indicate that above 0.5 g/L Pt-Ammine sorption, the platinisation of 10 × 50 mm IPMC samples through sodium borohydride reduction becomes redundant by the surface resistance metric. IPMCs with surface resistance values of approximately 2.5 Ω/square were obtained through only one round of chemical reduction. Varying surface morphologies and electrode thicknesses were analysed under a scanning electron microscope. The CCD parameter settings were validated. Recommended settings for optimised Pt-Ammine sorption in 10 × 50 mm Nafion-117 films were identified as follows: 1.0 g/L Pt-Ammine concentration, 24 h soak time, pH of 3 and temperature of 20 °C.

3.
Ir J Med Sci ; 192(3): 1115-1124, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35840827

RESUMEN

BACKGROUND: It is widely accepted that there is an association between diet and inflammatory bowel disease (IBD). Diet may play a role in disease pathogenesis but also in treatment and management of IBD. There is an increased interest in dietary aspects of people with IBD. AIMS: To investigate dietary practices, beliefs and behaviours of adults with IBD in Ireland. METHODS: An online questionnaire was adapted to explore dietary practices, beliefs and behaviours of people with IBD, and to identify any dietary modifications made due to their IBD. RESULTS: A total of 475 participants (female n = 354, male n = 121) took part in this study, 62% had Crohn's disease and 38% had ulcerative colitis. Dietary restrictions were imposed in the hope of preventing a relapse by 85% of participants. The most reported foods avoided included fatty foods (68%), spicy foods (64%) and raw vegetables or fruit (58%). Low fibre white plain foods (74%) appeared to improve symptoms during a relapse. Participant's appetites were higher during remission (8.36, SD = ± 1.95), compared to during relapse (3.71, SD = ± 2.32) (P ≤ 0.001). Almost three-quarters (73%) avoided the same menu as others living in their household and 56% avoided eating out to prevent or for fear of causing a relapse. Additionally, 70% avoided food or drink they liked to try prevent a relapse. CONCLUSION: These findings provide important insights into the dietary practices, beliefs and behaviours of adults with IBD. Its evident diet plays an important role, and our findings reiterate the importance of patient education and support.


Asunto(s)
Colitis Ulcerosa , Enfermedad de Crohn , Enfermedades Inflamatorias del Intestino , Humanos , Adulto , Masculino , Femenino , Estudios Transversales , Dieta , Recurrencia
4.
Sports Med ; 53(5): 993-1015, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36877405

RESUMEN

BACKGROUND: There has been a rise in the participation, professionalism, and profile of female sports in recent years. Sprinting ability is an important quality for successful athletic performance in many female team sports. However, much of the research to date on improving sprint performance in team sports is derived from studies with male participants. Given the biological differences between the sexes, this may be problematic for practitioners when programming to enhance sprint performance in female team-sport athletes. Therefore, the aims of this systematic review were to investigate (1) the overall effect of lower body strength training on sprint performance, and (2) the effect of specific strength training modalities (i.e., reactive-; maximal-; combined-; special-strength) on sprint performance in female team-sport athletes. METHODS: An electronic database search was performed using PubMed, MEDLINE, SPORTDiscus, CINAHL, The Cochrane Library, and SCOPUS to identify relevant articles. A random-effects meta-analysis was performed to establish standardised mean difference with 95% confidence intervals and the magnitude and direction of the effect. RESULTS: Fifteen studies were included in the final analysis. The 15 studies represent a total sample size of 362 participants (intervention n = 190; control n = 172) comprising 17 intervention groups and 15 control groups. The overall effects revealed small improvements in sprint performance in favour of the experimental group over 0-10 m and moderate improvements over sprint distances of 0-20 m and 0-40 m. The magnitude of improvement in sprint performance was influenced by the strength modality (i.e., reactive-, maximal-, combined-, and special-strength) utilised in the intervention. Reactive- and combined-strength training methods had a greater effect than maximal- or special-strength modalities on sprint performance. CONCLUSION: This systematic review and meta-analysis demonstrated that, when compared with a control group (i.e., technical and tactical training), the different strength training modalities exhibited small to moderate improvements in sprint performance in female team-sport athletes. The results of a moderator analysis demonstrated that youth athletes (< 18 years) yielded a greater improvement in sprint performance compared with adults (≥ 18 years). This analysis also supports the use of a longer programme duration (> 8 weeks) with a higher total number of training sessions (> 12 sessions) to improve overall sprint performance. These results will serve to guide practitioners when programming to enhance sprint performance in female team-sport athletes.


Asunto(s)
Rendimiento Atlético , Entrenamiento de Fuerza , Carrera , Adulto , Adolescente , Masculino , Humanos , Femenino , Entrenamiento de Fuerza/métodos , Deportes de Equipo , Atletas , Fuerza Muscular
5.
Cell Biol Int ; 36(1): 57-61, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21883092

RESUMEN

Nanoparticle cytotoxicity testing based on in vitro methods frequently lack consistency. Even the inclusion of the commonly employed growth supplement, FCS (fetal calf serum), generates variable results. Thus, our object was to investigate the effect of FCS concentration on the cytotoxic behaviour of the unmodified nanoclay, Cloisite® Na(+). Human monocytic U937 cells in medium supplemented with 5% FCS, 2.5% FCS or serum-free medium were treated with 1 mg/ml Cloisite Na(+). Cell growth in 2.5% FCS was significantly inhibited by Cloisite Na(+) within 48 h, whereas little effect was seen with a supplement of 5% FCS. Without serum, cell growth was inhibited and Cloisite Na(+) had a detrimental effect on these cells. In media supplemented with FCS, the nanoclays agglomerated together to form large bundles, whereas they were evenly dispersed throughout the medium in the absence of serum. Clay particles, therefore, have cytotoxic properties that may be linked to their dispersion pattern. These adverse effects seem to be masked by 5% FCS. Serum supplementation is an important consideration in the toxicological assessments of nanomaterials on cells, which needs to be addressed in the standardization of in vitro testing methods.


Asunto(s)
Silicatos de Aluminio/toxicidad , Nanopartículas/toxicidad , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Permeabilidad de la Membrana Celular , Supervivencia Celular/efectos de los fármacos , Arcilla , Medio de Cultivo Libre de Suero/farmacología , Humanos , Concentración de Iones de Hidrógeno , Células U937
6.
J Appl Toxicol ; 31(1): 27-35, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20677180

RESUMEN

The term 'nanoclay' generically refers to the natural clay mineral, montmorillonite, with silica and alumina as the dominant constituents. The incorporation of nanoclays into polymeric systems dramatically enhances their barrier properties as well as their thermal and mechanical resistance. Consequently, nanoclays are employed in a wide range of industrial applications with recent studies reporting potential use in the modulation of drug release. With the increase in manufacturing of nanoclay-containing products, information on the toxicological and health effects of nanoclay exposure is warranted. Thus, the objective of the present study was to evaluate the cytotoxicity of two different nanoclays: the unmodified nanoclay, Cloisite Na+ ®, and the organically modified nanoclay, Cloisite 93A®, in human hepatoma HepG2 cells. Following 24 h exposure the nanoclays significantly decreased cell viability. Cloisite Na+ induced intracellular reactive oxygen species (ROS) formation which coincided with increased cell membrane damage, whilst ROS generation did not play a role in Cloisite 93A-induced cell death. Neither of the nanoclays induced caspase-3/7 activation. Moreover, in the cell culture medium the nanoclays aggregated differently and this appeared to have an effect on their mechanisms of toxicity. Taken together, our data demonstrate that nanoclays are highly cytotoxic and as a result pose a possible risk to human health.


Asunto(s)
Apoptosis , Bentonita/toxicidad , Nanopartículas/toxicidad , Caspasa 3/metabolismo , Caspasa 7/metabolismo , Supervivencia Celular , Células Hep G2 , Humanos , Especies Reactivas de Oxígeno/metabolismo
7.
Pharmaceutics ; 12(3)2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-32121578

RESUMEN

: The effect of cooling on the degree of crystallinity, solid-state and dissolution properties of multi-component hot-melt extruded solid dispersions [SD] is of great interest for the successful formulation of amorphous SDs and is an area that is unreported, especially in the context of improving the stability of these specific systems. The thermal solid-state properties, degree of crystallinity, drug-polymer interactions, solubility and physical stability over time were investigated. X-ray powder diffraction [XRPD] and hyper differential scanning calorimetry [DSC] confirmed that indomethacin [INM] was converted to the amorphous state; however, the addition of poloxamer 407 [P407] had a significant effect on the degree of crystallinity and the solubility of the SD formulations. Spectroscopy studies identified the mechanism of interaction and solubility studies, showing a higher dissolution rate compared to amorphous and pure INM in pH 1.2 with a kinetic solubility of 20.63 µg/mL and 34.7 µg/mL after 3 and 24 h. XRPD confirmed that INM remained amorphous after 5 months stability testing in solid solutions with Poly(vinylpyrrolidone-co-vinyl acetate) [PVP VA64] and Plasdone S-630 [PL-S630]. Although cooling had a significant effect on the degree of crystallinity and on solubility of INM, the cooling method used did not have any significant effect on the amorphous stability of INM over time.

8.
J Mater Sci Mater Med ; 20(5): 1193-9, 2009 May.
Artículo en Inglés | MEDLINE | ID: mdl-19115091

RESUMEN

This body of work describes the development of a porous hydrogel for wound healing applications. In the present study poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) based hydrogels were prepared, and their properties were examined. Varying concentrations of the polymers and distilled water were used to prepare the hydrogels. The use of a high shear mixer, for foaming the PVA and PVA/PAA gels, and how this physical change can affect the structure and porosity of the hydrogel in question, represents a key feature of this work. The mechanical and thermal properties were determined by parallel plate rheometry and modulated differential scanning calorimetry (MDSC) respectively. The results indicated that the hydrogels containing low concentration of PVA and high volume of H(2)O are significantly weaker than those synthesised with higher concentrations of PVA. The thermal analysis shows distinct endotherms and provides evidence of crystallisation. The chemical structure of the hydrogels was confirmed by means of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR).


Asunto(s)
Resinas Acrílicas/química , Materiales Biocompatibles/química , Alcohol Polivinílico/química , Cicatrización de Heridas , Vendas Hidrocoloidales , Rastreo Diferencial de Calorimetría , Hidrogeles/química , Ensayo de Materiales , Reología , Espectroscopía Infrarroja por Transformada de Fourier , Propiedades de Superficie , Sustancias Viscoelásticas/química , Agua
9.
Gels ; 5(3)2019 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-31470691

RESUMEN

Previous studies involving poly N-vinylcaprolactam (PNVCL) and itaconic acid (IA) have synthesised the hydrogels with the presence of a solvent and a crosslinker, producing chemically crosslinked hydrogel systems. In this study, however, temperature sensitive PNVCL was physically crosslinked with a pH-sensitive comonomer IA through ultraviolet (UV) free-radical polymerization, without the presence of a solvent, to produce hydrogels with dual sensitivity. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy indicated successful polymerisation of the hydrogels. The temperature and pH sensitivity of the hydrogels was investigated. The lower critical solution temperature (LCST) of the gels was determined using the UV spectrometry and it was found that the incorporation of IA decreased the LCST. Rheology was conducted to investigate the mechanical and viscoelastic properties of the hydrogels, with results indicating IA that enhances the mechanical properties of the gels. Swelling studies were carried out at ~20 °C and 37 °C in different buffer solutions simulating the gastrointestinal tract (pH 2.2 and pH 6.8). In acidic conditions, the gels showed gradual increase in swelling while remaining structurally intact. While in basic conditions, the gels had a burst in swelling and began to gradually degrade after 30 min. Results were similar for drug release studies. Acetaminophen was incorporated into the hydrogels. Drug dissolution studies were carried out at 37 °C in pH 2.2 and pH 6.8. It was found that <20% of acetaminophen was released from the gels in pH 2.2, whereas the maximum drug released at pH 6.8 was 74%. Cytotoxicity studies also demonstrated the hydrogels to be highly biocompatible. These results indicate that physically crosslinked P(NVCL-IA) gels possess dual pH and temperature sensitive properties, which may be beneficial for biomedical applications such as drug delivery.

10.
J Mech Behav Biomed Mater ; 99: 1-10, 2019 11.
Artículo en Inglés | MEDLINE | ID: mdl-31319331

RESUMEN

The main aim of this study was to examine the stability of a range of polyethyleneglycol dimethacrylate (PEGDMA) hydrogels over a 28-day period in simulated physiological solution. Upon optimisation of the ultraviolet (UV) curing conditions, the PEGDMA hydrogels were prepared using four different monomer concentrations (25, 50, 75 and 100 wt% PEGDMA) in water and cross-linked by photopolymerisation. Initial results revealed a correlation between monomer concentration and swelling behaviour, where a decrease in swelling was observed with increase in monomer content. On storage in physiological solutions at 37 °C, a decrease in the weight remaining of the hydrogels and the pH of the solutions was observed over a 28-day period. Using scanning electron microscopy, the surface topography of the hydrogels appeared to get smoother and in parallel changes in hydrophilicty were observed, with the biggest changes observed for the higher monomer concentrations where water contact angle values were seen to increase toward 90°. However, the mechanical properties remained relatively unaffected and there was no adverse effect on cell metabolic activity observed for cells grown in the presence of PEGDMA samples or using elution methods. Looking at the combination of mechanical chemical and thermal properties shown these results are an important finding for scaffolds intended for tissue engineering applications, where provision of mechanical support without the elicitation of an inflammatory response due to polymer degradation products is crucial for successful integration and neotissue formation during the first 28 days post implantation.


Asunto(s)
Hidrogeles/química , Metacrilatos/química , Polietilenglicoles/química , Ingeniería de Tejidos/instrumentación , Ingeniería de Tejidos/métodos , Células 3T3 , Animales , Materiales Biocompatibles/química , Concentración de Iones de Hidrógeno , Ensayo de Materiales , Ratones , Osteoblastos/citología , Polímeros , Estrés Mecánico , Propiedades de Superficie , Temperatura , Rayos Ultravioleta
11.
Pharmaceutics ; 11(12)2019 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-31816898

RESUMEN

The introduction of three-dimensional printing (3DP) has created exciting possibilities for the fabrication of dosage forms, paving the way for personalized medicine. In this study, oral dosage forms of two drug concentrations, namely 2.50% and 5.00%, were fabricated via stereolithography (SLA) using a novel photopolymerizable resin formulation based on a monomer mixture that, to date, has not been reported in the literature, with paracetamol and aspirin selected as model drugs. In order to produce the dosage forms, the ratio of poly(ethylene glycol) diacrylate (PEGDA) to poly(caprolactone) triol was varied with diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure TPO) utilized as the photoinitiator. The fabrication of 28 dosages in one print process was possible and the printed dosage forms were characterized for their drug release properties. It was established that both drugs displayed a sustained release over a 24-h period. The physical properties were also investigated, illustrating that SLA affords accurate printing of dosages with some statistically significant differences observed from the targeted dimensional range, indicating an area for future process improvement. The work presented in this paper demonstrates that SLA has the ability to produce small, individualized batches which may be tailored to meet patients' specific needs or provide for the localized production of pharmaceutical dosage forms.

12.
Pharmaceutics ; 11(5)2019 May 18.
Artículo en Inglés | MEDLINE | ID: mdl-31109108

RESUMEN

Micro-injection moulding (µIM) was used for the production of enteric tablets of plasticised and unplasticised solid dispersions of poly(vinylpyrrolidone-vinyl acetate) (PVPVA), and the effect of the mechanical and thermal treatment on the properties of the dispersions was investigated. The physical state of the systems showed to be unaltered by the µIM step, maintaining the drug in the amorphous state. The dissolution profile of the tablets showed a slower dissolution rate due to the lower surface to volume ratio compared to the extruded strands. The lack of solubility of the doses in the acidic medium as a consequence of the acidity of indomethacin (IND) was observed. However, in neutral pH the drug dissolution showed slower rates without affecting the dissolution extent, showing a potential application for the development of controlled release doses. Overall, the production of tablets of amorphous solid dispersions (ASD), coupling hot-melt extrusion (HME) and µIM, proved to be a successful approach towards a continuous automated manufacturing process to improve the aqueous solubility of poorly water-soluble drugs.

13.
Eur J Pharm Biopharm ; 69(3): 1147-59, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18502627

RESUMEN

Hydrogel based devices belong to the group of swelling controlled drug delivery systems. Temperature responsive poly(N-isopropylacrylamide)-poly(vinylpyrrolidinone) random copolymers were produced by free radical polymerisation, using 1-hydroxycyclohexylphenyketone as an ultraviolet-light sensitive initiator, and poly(ethylene glycol) dimethacrylate as the crosslinking agent (where appropriate). The hydrogels were synthesised to have lower critical solution temperatures (LCST) near body temperature, which is favourable particularly for 'smart' drug delivery applications. Two model drugs (diclofenac sodium and procaine HCl) were entrapped within these xerogels, by incorporating the active agents prior to photopolymerisation. The properties of the placebo samples were contrasted with the drug-loaded copolymers at low levels of drug integration. Modulated differential scanning calorimetry (MDSC), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and atomic force microscopy (AFM) were used to investigate the influence of the drugs incorporated on the solid-state properties of the xerogels. MDSC and swelling studies were carried out to ascertain their effects on the LCST and swelling behaviour of the hydrated samples. In all cases, drug dissolution analysis showed that the active agent was released at a slower rate at temperatures above the phase transition temperature. Finally, preliminary in vitro cytotoxicity evaluations were performed to establish the toxicological pattern of the gels.


Asunto(s)
Preparaciones de Acción Retardada/química , Hidrogeles/química , Acrilamidas , Resinas Acrílicas , Antiinflamatorios no Esteroideos/administración & dosificación , Antiinflamatorios no Esteroideos/química , Rastreo Diferencial de Calorimetría , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Reactivos de Enlaces Cruzados , Diclofenaco/administración & dosificación , Diclofenaco/química , Humanos , Hidrogeles/toxicidad , Polímeros , Povidona , Procaína/administración & dosificación , Procaína/química , Solubilidad , Espectroscopía Infrarroja por Transformada de Fourier , Temperatura , Sales de Tetrazolio , Tiazoles , Rayos Ultravioleta
14.
Int J Pharm ; 351(1-2): 201-8, 2008 Mar 03.
Artículo en Inglés | MEDLINE | ID: mdl-18036753

RESUMEN

The body of work described in this research paper outlines the use of PEO/PCL blends in the production of monolithic matrices for oral drug delivery. Several batches of matrix material were prepared with carvedilol used as the active pharmaceutical ingredient. The matrices were prepared using various extrusion parameters to investigate the effect of screw speed and barrel temperature on the properties of the drug delivery devices. The resultant extrudate was characterised using steady state parallel plate rheometry, differential scanning calorimetry (DSC) and dissolution testing. Higher screw speeds were observed to result in slightly lower matrix melt viscosity when compared with matrices compounded using lower screw speeds. Dissolution testing showed that the incorporation of the hydrophobic PCL polymer into a PEO matrix results in a retarded drug release profile.


Asunto(s)
Carbazoles/química , Poliésteres/química , Propanolaminas/química , Tecnología Farmacéutica/métodos , Administración Oral , Rastreo Diferencial de Calorimetría , Carbazoles/administración & dosificación , Carvedilol , Preparaciones de Acción Retardada , Propanolaminas/administración & dosificación , Reología , Solubilidad , Temperatura
15.
Int J Pharm ; 549(1-2): 50-57, 2018 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-30016675

RESUMEN

The investigation of the miscibility between active pharmaceutical ingredients (API's) and polymeric excipients is of great interest for the formulation and development of amorphous solid dispersions, especially in the context of the prediction of the stability of these systems. Two different methods were applied to determine the miscibility between model compounds poly(vinylpyrrolidone-co-vinyl acetate) (PVPVA) and indomethacin (IND), viz. the measurement of the glass transition temperature (Tg) and the melting point depression method framed on the Flory-Huggins theory. Measurement of the glass transition temperatures of the binary blends showed the formation of an amorphous single phase system between the PVPVA and the IND regardless of the composition. Variation of Tg with the composition was well described by the Gordon-Taylor equation leading to the error of concluding lack of intermolecular interactions between the materials. Application of the Brostow-Chiu-Kalogeras-Vassilikou-Dova (BCKV) model shows a negative interaction parameter (a0) suggesting the presence of drug-drug intermolecular interactions. Application of the melting point depression method within the framework of the Flory-Huggins theory proved the miscibility of the system at temperatures close to the melting point of IND.


Asunto(s)
Química Farmacéutica/métodos , Excipientes/química , Indometacina/química , Pirrolidinas/química , Compuestos de Vinilo/química , Estabilidad de Medicamentos , Modelos Químicos , Transición de Fase , Solubilidad , Temperatura , Temperatura de Transición
16.
J Pharm Sci ; 107(5): 1372-1382, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29410037

RESUMEN

The optimal design of amorphous solid dispersion formulations requires the use of excipients to maintain supersaturation and improve physical stability to ensure shelf-life stability and better absorption during intestinal transit, respectively. Blends of excipients (surfactants and polymers) are often used within pharmaceutical products to improve the oral delivery of Biopharmaceutical Classification System class II drugs. Therefore, in this study, a dissolution enhancer, poloxamer 407 (P407), was investigated to determine its effect on the dissolution properties and on the amorphous nature of the active pharmaceutical ingredient contained in the formulation. Phase solubility studies of indomethacin (INM) in aqueous solutions of P407 and poly(vinylpyrrolidone-vinyl acetate copolymer) showed an increase in the kinetic solubility of INM compared with the pure drug at 37°C with a Ka value of 0.041 µg/mL. The solid dispersions showed a higher dissolution rate when compared to pure and amorphous drugs when performed in pH buffer 1.2 with a kinetic solubility of 21 µg/mL. The stability data showed that the amorphous drug in solid solutions with poly(vinylpyrrolidone-vinyl acetate copolymer) and P407 remained amorphous, and the %P407 loading had no effect on the amorphous stability of INM. This study concluded that the amorphous solid dispersion contributed to the increased solubility of INM.


Asunto(s)
Antiinflamatorios no Esteroideos/química , Compuestos Epoxi/química , Óxido de Etileno/química , Excipientes/química , Indometacina/química , Poloxámero/química , Povidona/análogos & derivados , Cristalización , Estabilidad de Medicamentos , Transición de Fase , Povidona/química , Solubilidad , Tensoactivos/química
17.
Eur J Pharm Biopharm ; 67(2): 377-86, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17398082

RESUMEN

We describe a drug delivery system based on a physically cross-linked poly(vinyl alcohol) (PVA) hydrogel for the release of Theophylline (TH). A composite was created by freezing an aqueous solution of PVA/NaOH onto a PVA/poly(acrylic acid) substrate. This formed a strong interface and demonstrated greater physical strength than the hydrogel alone. Such systems have potential for a variety of localised controlled drug delivery applications, for example, as coatings for implantable devices. Importantly, the results suggest that a versatile synthetic platform is possible that may provide different functional materials or combination of such. The resultant samples were characterised using optical microscopy, modulated differential scanning calorimetry (MDSC) and dissolution testing. The microstructure of the gels was examined using micro-thermal analysis (microTA) which is a combination of atomic force microscopy and thermal analysis. TH was found to have an effect on the crystalline structure and dissolution showed a Fickian release, suggesting that swelling and crystallinity were the controlling mechanisms.


Asunto(s)
Química Farmacéutica/métodos , Congelación , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Alcohol Polivinílico/química , Teofilina/química , Rastreo Diferencial de Calorimetría , Difusión , Portadores de Fármacos , Sistemas de Liberación de Medicamentos , Hidrogeles/química , Microscopía de Fuerza Atómica , Microesferas , Polímeros/química , Manejo de Especímenes , Temperatura
18.
Int J Pharm ; 329(1-2): 62-71, 2007 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-17010544

RESUMEN

The use of supercritical fluids as plasticisers in polymer processing has been well documented. The body of work described in this research paper outlines the use of a supercritical CO(2) assisted extrusion process in the preparation of a hot melt extruded monolithic polymer matrix for oral drug delivery. Several batches of matrix material were prepared with Carvedilol used as the active pharmaceutical ingredient (API). These batches were subsequently extruded both with and without supercritical CO(2) incorporation. The resultant matrices were characterised using steady-state parallel plate rheometry, differential scanning calorimetry (DSC), atomic force microscopy (AFM), micro-thermal analysis (microTA) and dissolution testing. Dissolution analysis showed that the use of supercritical CO(2) during the extrusion process resulted in a faster dissolution of API when compared with unassisted extrusion. The supercritical CO(2) incorporation also resulted in reduced viscosity during processing, therefore allowing for quicker throughput and productivity. The results detailed within this paper indicate that supercritical fluid assisted hot melt extrusion is a viable enhancement to conventional hot melt extrusion for the production of monolithic dosage forms.


Asunto(s)
Dióxido de Carbono , Preparaciones de Acción Retardada , Sistemas de Liberación de Medicamentos , Plastificantes , Polietilenglicoles , Administración Oral , Calor
19.
Eur J Pharm Biopharm ; 64(1): 75-81, 2006 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-16697170

RESUMEN

The use of filler materials in an extended release monolithic polymer matrix can lead to a vastly altered release profile for the active pharmaceutical ingredient. A range of excipients for use in monolithic matrices have been discussed in the literature. The body of work described in this research paper outlines the use of agar as a novel filler material in a hot melt extruded polymer matrix. Several batches of matrix material were prepared with Diclofenac sodium used as the active pharmaceutical ingredient (API). Agar and microcrystalline cellulose were used as the filler materials in varying ratios, to examine the effect of % filler content as well as filler type on the properties of the hot melt extruded matrix. The resultant extrudates were characterised using steady state parallel plate rheometry, differential scanning calorimetry (DSC) and dissolution testing. The rheometry analysis concluded that the fillers used resulted in an increase in the matrix viscosity. The DSC scans obtained showed negligible effects on the melting behavior of the matrix as a result of the filler inclusion. Dissolution analysis showed that the presence of the fillers resulted in a slower release rate of API than for the matrix alone. The results detailed within this paper indicate that agar is a viable filler for extended release hot melt produced dosage forms.


Asunto(s)
Agar/química , Química Farmacéutica/métodos , Diclofenaco/farmacología , Sistemas de Liberación de Medicamentos , Tecnología Farmacéutica/métodos , Rastreo Diferencial de Calorimetría , Preparaciones de Acción Retardada , Portadores de Fármacos , Composición de Medicamentos , Tamaño de la Partícula , Ácidos Polimetacrílicos/química , Solubilidad , Temperatura , Factores de Tiempo
20.
Int J Pharm ; 326(1-2): 50-9, 2006 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-16926073

RESUMEN

Copolymers of N-vinylpyrrolidinone and acrylic acid, crosslinked with ethylene glycol dimethacrylate and polyethylene glycol 600 dimethacrylate were prepared by UV-polymerisation. These polymers were analysed for their extractable content by Soxhlet extraction of the samples at 100 degrees C for 72 h. Aspirin and paracetamol were incorporated into the polymer structure at 25 wt.% during the curing process and their presence confirmed by Fourier transform infrared spectroscopy. It was found that the release rate of the drug from the polymer matrix was dependent on intermolecular bonding between the polymer and active agent with aspirin being released slower than paracetamol in all cases. Results showed that paracetamol was completely released after 24h whereas complete release of aspirin took up to 70 h. Finally preliminary in vitro biocompatibility testing was performed for crosslinked polyvinylpyrrolidinone, by determining human hepatoma HepG2 cell viability in the MTT assay and DNA damage in the comet assay following direct contact with various concentrations of polyvinylpyrrolidinone-containing media. Cytotoxicity data suggests a dose-dependent effect for both crosslinkers, with concentrations in the range 0.025-2.5 mg ml(-1) showing a marginal decrease in viability to, at most, 70% that of untreated cells. Again DNA migration in the comet assay following short-term exposure to EGDMA crosslinked hydrogels correlates with MTT data.


Asunto(s)
Resinas Acrílicas/química , Materiales Biocompatibles/química , Hidrogeles/química , Polímeros/química , Polivinilos/química , Pirrolidinonas/química , Acetaminofén/química , Aspirina/química , Supervivencia Celular , Química/métodos , Ensayo Cometa , Reactivos de Enlaces Cruzados/farmacología , Humanos , Concentración de Iones de Hidrógeno , Espectroscopía Infrarroja por Transformada de Fourier , Rayos Ultravioleta
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