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1.
Mar Drugs ; 18(2)2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-32079246

RESUMO

Chitin has been investigated in the context of finding new excipients suitable for direct compression, when subjected to roller compaction. Ball milling was concurrently carried out to compare effects from different energy or stress-inducing techniques. Samples of chitin powders (raw, processed, dried and humidified) were compared for variations in morphology, X-ray diffraction patterns, densities, FT-IR, flowability, compressibility and compactibility. Results confirmed the suitability of roller compaction to convert the fluffy powder of raw chitin to a bulky material with improved flow. X-ray powder diffraction studies showed that, in contrast to the high decrease in crystallinity upon ball milling, roller compaction manifested a slight deformation in the crystal lattice. Moreover, the new excipient showed high resistance to compression, due to the high compactibility of the granules formed. This was correlated to the significant extent of plastic deformation compared to the raw and ball milled forms of chitin. On the other hand, drying and humidification of raw and processed materials presented no added value to the compressibility and compactibility of the directly compressed excipient. Finally, compacted chitin showed direct compression similarity with microcrystalline cellulose when formulated with metronidazole (200 mg) without affecting the immediate drug release action of the drug.


Assuntos
Quitina/química , Composição de Medicamentos/métodos , Excipientes/química , Liberação Controlada de Fármacos , Tamanho da Partícula , Pós , Pressão , Comprimidos/química
2.
Molecules ; 25(22)2020 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-33198143

RESUMO

The objective of the research reported herein is to compare the compaction properties of three different chitin extracts from the organisms most used in the seafood industry; namely crabs, shrimps and squids. The foregoing is examined in relation to their polymorphic forms as well as compression and compaction behavior. Chitin extracted from crabs and shrimps exhibits the α-polymorphic form whilst chitin extracted from squid pins displays a ß-polymorphic form. These polymorphs were characterized using FTIR, X-ray powder diffraction and scanning electron microscopy. Pore diameter and volume differ between the two polymorphic powder forms. The ß form is smaller in pore diameter and volume. Scanning electron microscopy of the two polymorphic forms shows clear variation in the arrangement of chitin layers such that the α form appears more condensed due to the anti-parallel arrangement of the polymer chains. True, bulk and tapped densities of these polymorphs and their mixtures indicated poor flowability. Nevertheless, compression and compaction properties obtained by applying Heckle and Kawakita analyses indicated that both polymorphs are able to be compacted with differences in the extent of compaction. Chitin compacts, regardless of their origin, showed a very high crushing strength with very fast dissolution which makes them suitable for use as fast mouth dissolving tablets. Moreover, when different chitin powders are granulated with two model drugs, i.e., metronidazole and spiramycin they yielded high crushing strength and their dissolution profiles were in accordance with compendial requirements. It is concluded that the source of chitin extraction is as important as the polymorphic form when compression and compaction of chitin powders is carried out.


Assuntos
Quitina/química , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos , Pós , Força Compressiva , Composição de Medicamentos , Excipientes , Teste de Materiais , Metronidazol/química , Microscopia Eletrônica de Varredura , Porosidade , Pressão , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Espiramicina/química , Comprimidos , Água/química , Difração de Raios X
3.
Eur Biophys J ; 47(7): 723-737, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30066130

RESUMO

Despite the importance of membrane proteins in cellular processes, studies of these hydrophobic proteins present major technical challenges, including expression and purification for structural and biophysical studies. A modified strategy of that proposed previously by Saidijam et al. (2005) and others, for the routine expression of bacterial membrane proteins involved in environmental sensing and antimicrobial resistance (AMR), is proposed which results in purification of sufficient proteins for biophysical experiments. We report expression successes amongst a collection of enterococcal vancomycin resistance membrane proteins: VanTG, VanTG-M transporter domain, VanZ and the previously characterised VanS (A-type) histidine protein kinase (HPK). Using the same strategy, we report on the successful amplification and purification of intact BlpH and ComD2 HPKs of Streptococcus pneumoniae. Near-UV circular dichroism revealed both recombinant proteins bound their pheromone ligands BlpC and CSP2. Interestingly, CSP1 also interacted with ComD. Finally, we evaluate the alternative strategy for studying sensory HPKs involving isolated soluble sensory domain fragments, exemplified by successful production of VicKESD of Enterococcus faecalis VicK. Purified VicKESD possessed secondary structure post-purification. Thermal denaturation experiments using far-UV CD, a technique which can be revealing regarding ligand binding, revealed that: (a) VicKESD denaturation occurs between 15 and 50 °C; and (b) reducing conditions did not detectably affect denaturation profiles suggesting reducing conditions per se are not directly sensed by VicKESD. Our findings provide information on a modified strategy for the successful expression, production and/or storage of bacterial membrane HPKs, AMR proteins and sensory domains for their future crystallisation, and ligand binding studies.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Proteínas de Membrana/metabolismo , Feromônios/metabolismo , Sequência de Aminoácidos , Proteínas de Membrana/química , Desnaturação Proteica , Solubilidade , Temperatura
4.
Mar Drugs ; 15(10)2017 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-28946687

RESUMO

Hydrophilic matrices composed of chitosan (CS) and xanthan gum (XG) complexes are of pharmaceutical interest in relation to drug delivery due to their ability to control the release of active ingredients. Molecular dynamics simulations (MDs) have been performed in order to obtain information pertaining to the effect of the state of protonation and degree of N-acetylation (DA) on the molecular conformation of chitosan and its ability to interact with xanthan gum in aqueous solutions. The conformational flexibility of CS was found to be highly dependent on its state of protonation. Upon complexation with XG, a substantial restriction in free rotation around the glycosidic bond was noticed in protonated CS dimers regardless of their DA, whereas deprotonated molecules preserved their free mobility. Calculated values for the free energy of binding between CS and XG revealed the dominant contribution of electrostatic forces on the formation of complexes and that the most stable complexes were formed when CS was at least half-protonated and the DA was ≤50%. The results obtained provide an insight into the main factors governing the interaction between CS and XG, such that they can be manipulated accordingly to produce complexes with the desired controlled-release effect.


Assuntos
Quitosana/química , Polissacarídeos Bacterianos/química , Acetilação , Interações Hidrofóbicas e Hidrofílicas , Simulação de Dinâmica Molecular , Eletricidade Estática , Água/química
5.
Anal Chem ; 87(9): 4996-5003, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25874899

RESUMO

Hematocrit (HCT)-based assay bias (composed of area and recovery bias) is an important contributing factor to the barriers that currently hinder the development and acceptance of dried blood spots (DBS) as a widely used quantitative bioanalytical sampling technique for regulatory studies. This article describes the evaluation of a practical internal standard spray addition technique, used prior to LC-MS/MS analysis, which is demonstrated to nullify the effect of recovery bias. To our knowledge, this is the first time a potential solution to HCT-based recovery bias has been investigated in detail and reported in the literature. This new technique is coupled with accurate volume DBS sampling, whole-spot extraction, and automated direct elution techniques to demonstrate a workflow that both nullifies HCT-based assay bias and the additional manual extraction burden associated with DBS analysis.


Assuntos
Teste em Amostras de Sangue Seco , Cromatografia Líquida , Hematócrito , Humanos , Espectrometria de Massas em Tandem
6.
Analyst ; 140(20): 6814-23, 2015 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-26131453

RESUMO

Ion mobility mass spectrometry is used to measure the drift-time of an ion. The drift-time of an ion can be used to calculate the collision cross-section (CCS) in travelling wave ion mobility (e.g. Waters Synapt and Vion instruments) or directly determine the experimental CCS (e.g. Agilent 6560 instrument and many drift-tube instruments). A comparison of the experimental CCS and theoretical CCS values obtained from trajectory method He(g) parameterised MOBCAL and N2(g) parameterised MOBCAL software, for a range of 20 'small molecules' is presented. This study utilises density functional theory B3LYP methods and the 6-31G+(d,p) basis set to calculate theoretical CCS values. This study seeks to assess the accuracy of a common procedure using CCS calibration with poly-(d/l)-alanine derived from drift-cell measurements and the original release of MOBCAL software and compare it with recent improvements with a drug-like molecule calibration set and a revision of MOBCAL parameterised for N2(g) drift gas. This study represents one of the first quantitative evaluations of the agreement between theoretical CCS and experimental CCS values for a range of small pharmaceutically relevant molecules using travelling wave ion mobility mass spectrometry. Accurate theoretical CCS may allow optimisation of ion mobility separations in silico, provide CCS databases that can confirm structures without the need for alternative analytical tools such as nuclear magnetic resonance spectroscopy (NMR) and assignment of unknowns and positional isomers without requiring reference materials.


Assuntos
Espectrometria de Massas , Modelos Moleculares , Compostos Orgânicos/química , Calibragem , Nitrogênio/química , Teoria Quântica , Software
7.
J Phys Chem A ; 119(46): 11280-92, 2015 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-26496173

RESUMO

IR and Raman spectra of eugenol, isoeugenol and methyl eugenol have been obtained in the liquid phase. Vibrational spectroscopic results are discussed in relation to computed structures and spectra of the low energy conformations of these molecules obtained from DFT calculations at the B3LYP/cc-pVTZ level. Although computed differences in vibrational spectra for the different conformers were generally small, close examination, in conjunction with the experimental spectra, enabled conformational analysis of all three molecules. Anharmonic contributions to computed vibrational spectra were obtained from calculations of cubic and quartic force constants at the B3LYP/DZ level. This permitted the determination of the anharmonic fundamentals for comparison with the experimental IR and Raman band positions, leading to an excellent fit between calculated and experimental spectra. Band assignments were obtained in terms of potential energy distributions (ped's).

8.
Mar Drugs ; 13(4): 1765-84, 2015 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-25830681

RESUMO

The aim of the work reported herein was to investigate the effect of various low molecular weight chitosans (LMWCs) on the stability of insulin using USP HPLC methods. Insulin was found to be stable in a polyelectrolyte complex (PEC) consisting of insulin and LMWC in the presence of a Tris-buffer at pH 6.5. In the presence of LMWC, the stability of insulin increased with decreasing molecular weight of LMWC; 13 kDa LMWC was the most efficient molecular weight for enhancing the physical and chemical stability of insulin. Solubilization of insulin-LMWC polyelectrolyte complex (I-LMWC PEC) in a reverse micelle (RM) system, administered to diabetic rats, results in an oral delivery system for insulin with acceptable bioactivity.


Assuntos
Quitina/análogos & derivados , Diabetes Mellitus Experimental/tratamento farmacológico , Sistemas de Liberação de Medicamentos , Eletrólitos/química , Excipientes/química , Hipoglicemiantes/administração & dosagem , Insulina/administração & dosagem , Administração Oral , Animais , Disponibilidade Biológica , Biotransformação , Quitina/química , Quitosana , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/metabolismo , Liberação Controlada de Fármacos , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Hiperglicemia/prevenção & controle , Hipoglicemiantes/sangue , Hipoglicemiantes/farmacocinética , Hipoglicemiantes/uso terapêutico , Insulina/análogos & derivados , Insulina/análise , Insulina/sangue , Insulina/farmacocinética , Insulina/uso terapêutico , Masculino , Micelas , Peso Molecular , Oligossacarídeos , Tamanho da Partícula , Distribuição Aleatória , Ratos Sprague-Dawley
9.
Mar Drugs ; 13(4): 1739-64, 2015 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-25830680

RESUMO

This study describes the preparation, characterization and performance of a novel excipient for use in oro-dispersible tablets (ODT). The excipient (Cop-CM) consists of chitin and mannitol. The excipient with optimal physicochemical properties was obtained at a chitin: mannitol ratio of 2:8 (w/w) and produced by roll compaction (RC). Differential scanning calorimetry (DSC), Fourier transform-Infrared (FT-IR), X-ray powder diffraction (XRPD) and scanning electron microscope (SEM) techniques were used to characterize Cop-CM, in addition to characterization of its powder and ODT dosage form. The effect of particle size distribution of Cop-CM was investigated and found to have no significant influence on the overall tablet physical properties. The compressibility parameter (a) for Cop-CM was calculated from a Kawakita plot and found to be higher (0.661) than that of mannitol (0.576) due to the presence of the highly compressible chitin (0.818). Montelukast sodium and domperidone ODTs produced, using Cop-CM, displayed excellent physicochemical properties. The exceptional binding, fast wetting and superdisintegration properties of Cop-CM, in comparison with commercially available co-processed ODT excipients, results in a unique multifunctional base which can successfully be used in the formulation of oro-dispersible and fast immediate release tablets.


Assuntos
Antiasmáticos/administração & dosagem , Antieméticos/administração & dosagem , Quitina/química , Sistemas de Liberação de Medicamentos , Excipientes/química , Manitol/química , Acetatos/administração & dosagem , Acetatos/química , Administração Oral , Antiasmáticos/química , Antieméticos/química , Varredura Diferencial de Calorimetria , Fenômenos Químicos , Quitina/ultraestrutura , Ciclopropanos , Domperidona/administração & dosagem , Domperidona/química , Composição de Medicamentos , Liberação Controlada de Fármacos , Humanos , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Difração de Pó , Quinolinas/administração & dosagem , Quinolinas/química , Espectroscopia de Infravermelho com Transformada de Fourier , Sulfetos , Comprimidos , Água/análise
10.
Matern Child Nutr ; 11(2): 202-14, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23020067

RESUMO

Quantitative analyses of the macronutrient content of eight popular commercial 'ready-to-feed' baby meals for 6-9-month old infants in the UK market have been undertaken in order to ascertain their nutritional suitability in relation to the total daily dietary intake as well as nutritional profiling of the products. The chemical analyses conducted included Kjeldhal for protein, acid hydrolysis and extraction for fat, phenol sulphuric acid for carbohydrate and Association of Official Analytical Chemists 985.29 for fibre. The only difference found between different varieties (meat- and vegetable-based) was with respect to the protein content (P=0.04) per 100 g of food. The experimentally determined concentrations of macronutrients (g/100 kcal) were compared with the declared values provided by the manufacturers on the product labels and, despite some variations, the values obtained comply with regulatory requirements (Commission Directive 2006/125/EC). The total daily intake of fat (27.0 g per day) - based on the menu composed from commercial complementary food - is suggested to exceed the daily recommended values for fat (31%), if the intake of snacks and desserts are incorporated. These findings imply that the formulation of recipes, based on a standard commercial menu, is an important consideration in relation to the nutritional quality of the diet of infants.


Assuntos
Alimentos Infantis/análise , Valor Nutritivo , Carboidratos da Dieta/análise , Gorduras na Dieta/análise , Fibras na Dieta/análise , Proteínas Alimentares/análise , Ingestão de Energia , Rotulagem de Alimentos/normas , Humanos , Lactente , Carne , Reino Unido , Verduras
11.
Mass Spectrom Rev ; 32(1): 43-71, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-22941854

RESUMO

The phenomenon of ion mobility (IM), the movement/transport of charged particles under the influence of an electric field, was first observed in the early 20th Century and harnessed later in ion mobility spectrometry (IMS). There have been rapid advances in instrumental design, experimental methods, and theory together with contributions from computational chemistry and gas-phase ion chemistry, which have diversified the range of potential applications of contemporary IMS techniques. Whilst IMS-mass spectrometry (IMS-MS) has recently been recognized for having significant research/applied industrial potential and encompasses multi-/cross-disciplinary areas of science, the applications and impact from decades of research are only now beginning to be utilized for "small molecule" species. This review focuses on the application of IMS-MS to "small molecule" species typically used in drug discovery (100-500 Da) including an assessment of the limitations and possibilities of the technique. Potential future developments in instrumental design, experimental methods, and applications are addressed. The typical application of IMS-MS in relation to small molecules has been to separate species in fairly uniform molecular classes such as mixture analysis, including metabolites. Separation of similar species has historically been challenging using IMS as the resolving power, R, has been low (3-100) and the differences in collision cross-sections that could be measured have been relatively small, so instrument and method development has often focused on increasing resolving power. However, IMS-MS has a range of other potential applications that are examined in this review where it displays unique advantages, including: determination of small molecule structure from drift time, "small molecule" separation in achiral and chiral mixtures, improvement in selectivity, identification of carbohydrate isomers, metabonomics, and for understanding the size and shape of small molecules. This review provides a broad but selective overview of current literature, concentrating on IMS-MS, not solely IMS, and small molecule applications.

12.
Drug Dev Ind Pharm ; 40(2): 145-56, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23763436

RESUMO

The majority of active pharmaceutical ingredients (APIs) found in oral dosage forms have a bitter taste. Masking the unpleasant taste of bitter, APIs is a major challenge in the development of such oral dosage forms. Taste assessment is an important quality-control parameter for evaluating taste-masked formulations of any new molecular entity. Hot-melt extrusion (HME) techniques, have very recently, been accepted from an industrial compliance viewpoint in relation to both manufacturing operations and development of pharmaceuticals. HME achieves taste masking of bitter APIs via various mechanisms such as the formation of solid dispersions and inter-molecular interactions and this has led to its wide-spread use in pharmaceutical formulation research. In this article, the uses of various taste evaluation methods and HME as continuous processing techniques for taste masking of bitter APIs used for the oral delivery of drugs are reviewed.


Assuntos
Química Farmacêutica/métodos , Temperatura Alta , Preparações Farmacêuticas/química , Paladar/efeitos dos fármacos , Administração Oral , Animais , Avaliação Pré-Clínica de Medicamentos/métodos , Humanos , Preparações Farmacêuticas/administração & dosagem , Paladar/fisiologia
13.
Mol Pharm ; 10(11): 4281-93, 2013 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-24099044

RESUMO

Sirolimus has recently been introduced as a therapeutic agent for breast and prostate cancer. In the current study, conventional and Stealth liposomes were used as carriers for the encapsulation of sirolimus. The physicochemical characteristics of the sirolimus liposome nanoparticles were investigated including the particle size, zeta potential, stability and membrane integrity. In addition atomic force microscopy was used to study the morphology, surface roughness and mechanical properties such as elastic modulus deformation and deformation. Sirolimus encapsulation in Stealth liposomes showed a high degree of deformation and lower packing density especially for dipalmitoyl-phosphatidylcholine (DPPC) Stealth liposomes compared to unloaded. Similar results were obtained by differential scanning calorimetry (DSC) studies; sirolimus loaded liposomes were found to result in a distorted state of the bilayer. X-ray photon electron (XPS) analysis revealed a uniform distribution of sirolimus in multilamellar DPPC Stealth liposomes compared to a nonuniform, greater outer layer lamellar distribution in distearoylphosphatidylcholine (DSPC) Stealth liposomes.


Assuntos
1,2-Dipalmitoilfosfatidilcolina/química , Lipossomos/química , Sirolimo/química , Varredura Diferencial de Calorimetria , Microscopia de Força Atômica
14.
Rapid Commun Mass Spectrom ; 27(21): 2399-410, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-24097396

RESUMO

RATIONALE: Ion mobility spectrometry-mass spectrometry (IMS-MS) offers an opportunity to combine measurements and/or calculations of the collision cross-sections and subsequent mass spectra with computational modelling in order to derive the three-dimensional structure of ions. IMS-MS has previously been reported to separate two components for the compound norfloxacin, explained by protonation on two different sites, enabling the separation of protonated isomers (protomers) using ion mobility with distinguishable tandem mass spectrometric (MS/MS) data. This study reveals further insights into the specific example of norfloxacin and wider implications for ion mobility mass spectrometry. METHODS: Using a quadrupole ion mobility time-of-flight mass spectrometer, the IMS and MS/MS spectra of norfloxacin were recorded and compared with theoretical calculations using molecular modelling (density functional theory), and subsequent collision cross-section calculations using projection approximation. RESULTS: A third significant component in the ion mobilogram of norfloxacin was observed under similar experimental conditions to those previously reported. The presence of the new component is convoluted by co-elution with another previously observed component. CONCLUSIONS: This case demonstrates the potential of combined IMS-MS/MS with molecular modelling information for increased understanding of 'small-molecule' fragmentation pathways.

15.
Phys Chem Chem Phys ; 15(46): 20046-53, 2013 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-24154789

RESUMO

γ-Aminobutyric acid (GABA), and its positional isomers DL-α-aminobutyric acid (AABA) and DL-ß-aminobutyric acid (BABA) have been analysed, in the solid state, using thermally stimulated current (TSC) spectroscopy. Secondary relaxations in these molecules have been detected for the first time. GABA displays two secondary relaxations at 77 ± 2 °C and 114 ± 2 °C, whilst AABA and BABA each display a single secondary relaxation at 109 ± 1 °C and 104 ± 1 °C, respectively. Analysis (decoupling of molecular mobilities) of secondary relaxations using thermal windowing (TW) and relaxation map analysis (RMA) show that the dipole relaxation associated with secondary transitions observed for the aminobutyric acids requires activation energies of 189.9 ± 3.2 kJ mol(-1) (GABA), 142.4 ± 1.4 kJ mol(-1) (AABA) and 195.7 ± 0.8 kJ mol(-1) (BABA). However, the ΔH(≠) values observed were found to exhibit negligible deviations from the zero entropy line. This indicates that the relaxation processes are localised, non-cooperative rotational motions that have a negligible influence on entropy changes of detected molecular mobilities. Furthermore, RMA analysis revealed that AABA and BABA display compensation behaviour i.e., entropy and enthalpy are linearly related to each other, whereas GABA did not demonstrate such behaviour. The coordinates of the compensation point (compensation temperature (Tc) and the compensation relaxation time (τc)) were found to be 214 ± 6 °C and 0.051 ± 0.024 s, respectively for AABA and 153 ± 3 °C and 0.025 ± 0.011 s for BABA. For the molecules investigated the compensation points coincide with the starting temperature of the higher temperature thermal events i.e. sublimation, melt/decomposition, and indicate a correlation between secondary relaxation processes and the main thermal transitions, found via TGA and DSC studies.


Assuntos
Varredura Diferencial de Calorimetria , Termogravimetria , Ácido gama-Aminobutírico/análise , Aminobutiratos/análise , Entropia , Isomerismo , Temperatura
16.
Drug Dev Ind Pharm ; 38(10): 1207-20, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22204701

RESUMO

Bioadhesive buccal films are innovative dosage forms with the ability to adhere to the mucosal surface and subsequently hydrate to release and deliver drugs across the buccal membrane. This study aims to formulate and characterize stable carrageenan (CAR) based buccal films with desirable drug loading capacity. The films were prepared using CAR, poloxamer (POL) 407, various grades of PEG (plasticizer) and loaded with paracetamol (PM) and indomethacin (IND) as model soluble and insoluble drugs, respectively. The films were characterized by texture analysis, thermogravimetric analysis (TGA), DSC, scanning electron microscopy, X-ray powder diffraction (XRPD), and in vitro drug release studies. Optimized films were obtained from aqueous gels comprising 2.5% w/w κ-CAR 911, 4% w/w POL 407 and 6% w/w (PM) and 6.5% w/w (IND) of PEG 600 with maximum drug loading of 1.6% w/w and 0.8 % w/w for PM and IND, respectively. TGA showed residual water content of approximately 5% of films dry weight. DSC revealed a T(g) at 22.25 and 30.77°C for PM and IND, respectively, implying the presence of amorphous forms of both drugs which was confirmed by XRPD. Drug dissolution profiles in simulated saliva showed cumulative percent release of up to 45 and 57% of PM and IND, respectively, within 40 min of contact with dissolution medium simulating saliva.


Assuntos
Acetaminofen/química , Química Farmacêutica/métodos , Sistemas de Liberação de Medicamentos/métodos , Indometacina/química , Mucosa Bucal/metabolismo , Acetaminofen/administração & dosagem , Varredura Diferencial de Calorimetria/métodos , Carragenina/química , Formas de Dosagem , Estabilidade de Medicamentos , Indometacina/administração & dosagem , Microscopia Eletrônica de Varredura/métodos , Poloxâmero/química , Polietilenoglicóis/química , Saliva/metabolismo , Solubilidade , Água/química , Difração de Raios X/métodos
17.
Food Chem ; 128(1): 123-8, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-25214338

RESUMO

There is a paucity of data in respect of the nutritional quality of complementary foods for infants and young children aged between 6 and 12months. The primary objective of this study was to examine nutritive values of such complementary infant food on the UK market in order to ascertain their suitability relative to dietary guidelines for the 6-9months age group. Quantitative analyses were conducted on eight different products representing four popular brands (meat and vegetable based) currently on sale in the UK. Eight major mineral and trace elements, namely: calcium, copper, magnesium, iron, zinc, potassium, sodium and selenium were measured by ICP-OES and ICP-MS. The results of these studies were referenced to the Recommended Nutrient Intake (RNI) values for 6-9months old children, and a menu of entire daily intake of minerals and trace elements was composed taking into consideration the nutrient and energy intake from milk consumption. Based on these comparisons, all the food samples studied in this work contained less essential minerals than expected from the RNI values except for potassium in meat and vegetable based recipes. These results suggest that commercial complementary infant foods on the UK market may not contain the minimum levels of minerals required for the labelling declaration of micronutrient content (Commission Directive 2006/125/EC). This provides opportunities and scope for product optimisation to improve their nutritive value.

18.
Mater Sci Eng C Mater Biol Appl ; 127: 111946, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34225843

RESUMO

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor in Chief following the internal investigation at the University of Sussex and University of Greenwich. The investigation found that the corresponding author, Dr Mohammed Maniruzzaman, used unpublished experimental data from earlier research projects without securing the necessary permissions and approvals from the University of Greenwich.

19.
Acta Crystallogr C ; 66(Pt 2): o71-8, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20124685

RESUMO

The solid-state structures of a series of seven substituted 3-methylidene-1H-indol-2(3H)-one derivatives have been determined by single-crystal X-ray diffraction and are compared in detail. Six of the structures {(3Z)-3-(1H-pyrrol-2-ylmethylidene)-1H-indol-2(3H)-one, C(13)H(10)N(2)O, (2a); (3Z)-3-(2-thienylmethylidene)-1H-indol-2(3H)-one, C(13)H(9)NOS, (2b); (3E)-3-(2-furylmethylidene)-1H-indol-2(3H)-one monohydrate, C(13)H(9)NO(2).H(2)O, (3a); 3-(1-methylethylidene)-1H-indol-2(3H)-one, C(11)H(11)NO, (4a); 3-cyclohexylidene-1H-indol-2(3H)-one, C(14)H(15)NO, (4c); and spiro[1,3-dioxane-2,3'-indolin]-2'-one, C(11)H(11)NO(3), (5)} display, as expected, intermolecular hydrogen bonding (N-H...O=C) between the 1H-indol-2(3H)-one units. However, methyl 3-(1-methylethylidene)-2-oxo-2,3-dihydro-1H-indole-1-carboxylate, C(13)H(13)NO(3), (4b), a carbamate analogue of (4a) lacking an N-H bond, displays no intermolecular hydrogen bonding. The structure of (4a) contains three molecules in the asymmetric unit, while (4b) and (4c) both contain two independent molecules.


Assuntos
Cristalografia por Raios X , Indóis/química , Proteínas Tirosina Quinases/antagonistas & inibidores , Pirróis/química , Modelos Moleculares , Estrutura Molecular , Sunitinibe
20.
AAPS PharmSciTech ; 11(4): 1558-71, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21052880

RESUMO

A co-processed excipient was prepared from commercially available crystalline mannitol and α-chitin using direct compression as well as spray, wet, and dry granulation. The effect of the ratio of the two components, percentage of lubricant and particle size, on the properties of the prepared co-processed excipient has been investigated. α-Chitin forms non-hygroscopic, highly compactable, disintegrable compacts when co-processed with crystalline mannitol. The compaction properties of the co-processed mannitol-chitin mixture were found to be dependent upon the quantity of mannitol added to chitin, in addition to the granulation procedure used. Optimal physicochemical properties of the excipient, from a manufacturing perspective, were obtained using a co-processed mannitol-chitin (2:8, w/w) mixture prepared by wet granulation (Cop-MC). Disintegration time, crushing strength, and friability of tablets, produced from Cop-MC using magnesium stearate as a lubricant, were found to be independent of the particle size of the prepared granules. The inherent binding and disintegration properties of the compressed Cop-MC are useful for the formulation of poorly compressible, high-strength, and low-strength active pharmaceutical ingredients. The ability to co-process α-chitin with crystalline mannitol allows chitin to be used as a valuable industrial pharmaceutical excipient.


Assuntos
Quitina/química , Composição de Medicamentos/métodos , Excipientes/química , Lubrificantes/química , Manitol/química , Ácidos Esteáricos/química , Fenômenos Químicos , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Comprimidos , Molhabilidade
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