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2.
Int J Pharm ; 547(1-2): 291-302, 2018 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-29883791

RESUMO

This study examines the preparation of sustained-release lidocaine polyelectrolyte complex using reactive melt extrusion. Eudragit L100-55 was selected as the ionic polymer. The influence of drug forms (freebase vs. hydrochloride salt) on lidocaine-Eudragit L100-55 interactions, physical stability, and dissolution properties of extrudates was investigated. It was confirmed by DSC, FT-IR and Raman spectroscopy that polyelectrolyte could only form via the acid-base reaction between Eudragit L100-55 and lidocaine freebase. Due to this ionic interaction, the lidocaine extrudate was physically more stable than the lidocaine hydrochloride extrudate during the storage under stressed condition. Drug release from lidocaine extrudate was a function of drug solubility, polymer solubility, drug-polymer interaction, and drug-induced microenvironment pH. At 30% drug loading, extrudate exhibited sustained release in aqueous media at pH 1.2 and 4.5. Due to the alkaline microenvironment pH induced by dissolved lidocaine, Eudragit L100-55 was solubilized and sustained-release was not achieved in water and aqueous media at pH 5.5. In comparison, lidocaine hydrochloride induced an acidic microenvironment. Drug release of lidocaine hydrochloride extrudate was similar at pH 1.2, 4.5, 5.5 and water with drug being released over 10 h. The release of lidocaine hydrochloride from the extrudates in these media was primarily controlled by microenvironment pH. It is concluded that different forms of lidocaine resulted in different drug-polymer interactions and distinctive physicochemical properties of extrudates.


Assuntos
Resinas Acrílicas/química , Química Farmacêutica/métodos , Portadores de Fármacos/química , Lidocaína/administração & dosagem , Anestésicos Locais/administração & dosagem , Anestésicos Locais/química , Varredura Diferencial de Calorimetria , Preparações de Ação Retardada , Liberação Controlada de Fármacos , Concentração de Íons de Hidrogênio , Lidocaína/química , Polímeros/química , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Água/química
3.
Int J Offender Ther Comp Criminol ; 62(11): 3499-3508, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29161911

RESUMO

Naikan is a contemplative self-observation practice that originated from Japanese Shin Buddhism and is utilized for rehabilitating prison inmates in many countries. Although some investigations have provided initial evidence for its efficiency in decreasing recidivism, there is still a need for further investigation of the effectiveness of Naikan on other outcomes through more controlled studies. The present study aimed to investigate the efficacy of Naikan therapy on male offenders' perceived social support and externalized blame. Ninety-two male offenders were randomly assigned to either the experimental group or to the waiting group. All participants were evaluated by the Multidimensional Scale of Perceived Social Support and the Externalization subscale of the Test of Self-Conscious Affect before and after Naikan therapy. The results suggested that participants who received Naikan therapy showed higher levels of perceived social support and lower levels of externalized blame after Naikan therapy than before.


Assuntos
Prisioneiros , Psicoterapia/métodos , Apoio Social , Adulto , China , Humanos , Masculino , Pessoa de Meia-Idade , Distribuição Aleatória , Adulto Jovem
4.
J Control Release ; 243: 11-20, 2016 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-27693750

RESUMO

Nanoparticle formulations have found increasing applications in modern therapies. To achieve desired treatment efficacy and safety profiles, drug release kinetics of nanoparticles must be controlled tightly. However, actual drug release kinetics of nanoparticles cannot be readily measured due to technique difficulties, although various methods have been attempted. Among existing experimental approaches, dialysis method is the most widely applied one due to its simplicity and avoidance of separating released drug from the nanoparticles. Yet this method only measures the released drug in the medium outside a dialysis device (the receiver), instead of actual drug release from the nanoparticles inside the dialysis device (the donor). Thus we proposed a new method using numerical deconvolution to evaluate actual drug release kinetics of nanoparticles inside the donor based on experimental release profiles of nanoparticles and free drug solution in the receptor determined by existing dialysis tests. Two computer programs were developed based on two different numerical methods, namely least square criteria with prescribed Weibull function or orthogonal polynomials as input function. The former was used for all analyses in this work while the latter for verifying the reliability of the predictions. Experimental data of drug release from various nanoparticle formulations obtained from different dialysis settings and membrane pore sizes were used to substantiate this approach. The results demonstrated that this method is applicable to a broad range of nanoparticle and microparticle formulations requiring no additional experiments. It is independent of particle formulations, drug release mechanisms, and testing conditions. This new method may also be used, in combination with existing dialysis devices, to develop a standardized method for quality control, in vitro-in vivo correlation, and for development of nanoparticles and other types of dispersion formulations.


Assuntos
Química Farmacêutica/métodos , Diálise/métodos , Nanopartículas , Preparações Farmacêuticas/administração & dosagem , Liberação Controlada de Fármacos , Cinética , Preparações Farmacêuticas/química , Reprodutibilidade dos Testes , Software
5.
J Environ Sci (China) ; 40: 3-9, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26969539

RESUMO

The rate constant for the gas-phase reaction of O3 and Lewisite was studied in air using the smog chamber technique. The experiments were carried out under pseudo-first-order reaction conditions with [O3]≪[Lewisite]. The observed rate constant of O3 with Lewisite was (7.83 ± 0.38) × 10(-19)cm(3)/(molecule·sec) at 298 ± 2K. Lewisite was discussed in terms of reactivity with O3 and its relationship with the ionization potential. Our results show that the rate constant for the gas-phase reaction of O3 with Lewisite is in line with the trend of the rate constants of O3 with haloalkenes.


Assuntos
Arsenicais/química , Ozônio/química , Atmosfera , Substâncias para a Guerra Química/química , Cromatografia Gasosa , Cinética , Smog , Espectroscopia de Infravermelho com Transformada de Fourier
6.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(2): 466-9, 2015 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-25970914

RESUMO

The vapor infrared transmission spectra of varied concentration of lewisite-1 were measured by a long-path FT-IR spectrometer, and its characteristic frequencies are 814, 930, 1563 cm(-1); their infrared absorption cross section (a) were determined using Beer-Lambert law. The corresponding sigma values are 3.89 +/- 0.01, 1.43 +/- 0.06, 4.47 +/- 0.05 ( X 10(-20) cm2 x molecule(-1)). Two little teeny peaks, 1158, 1288 cm(-1) were found in the measured spectra. Density Functional Theory (DFT) was applied to calculated the infrared spectra of lewisite-1, -2, -3 on a b3lyp/6-311+g(d, p) level by Gauss09 package. The vibration modes were assigned by Gaussview5. 08. The calculated spectra and experimental spectra are in good agreement with each other in 600-1600 cm(-1) range, for the Person's r is 0.9991. The calculated spectra also showed three characteristic frequencies (293, 360, 374 cm(-1)) related to As atom. 0.977 was a scaling factor we determined for lewisite-1 through least-square error and its performance to scale lewisite-1, -2, -3 was acceptable. The results of this work are useful for monitoring environmental atmospheric concentrations of lewisite.

7.
Inorg Chem ; 53(24): 12841-7, 2014 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-25423999

RESUMO

New pink organic-inorganic layered cobalt hydroxide nanofibers intercalated with benzoate ions [Co(OH)(C6H5COO)·H2O] have been synthesized by using cobalt nitrate and sodium benzoate as reactants in water with no addition of organic solvent or surfactant. The high-purity nanofibers are single-crystalline in nature and very uniform in size with a diameter of about 100 nm and variable lengths over a wide range from 200 µm down to 2 µm by simply adjusting reactant concentrations. The as-synthesized products are well-characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), fast Fourier transforms (FFT), X-ray diffraction (XRD), energy dispersive X-ray spectra (EDX), X-ray photoelectron spectra (XPS), elemental analysis (EA), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), and UV-vis diffuse reflectance spectra (UV-vis). Our results demonstrate that the structure consists of octahedral cobalt layers and the benzoate anions, which are arranged in a bilayer due to the π-π stacking of small aromatics. The carboxylate groups of benzoate anions are coordinated to Co(II) ions in a strong bridging mode, which is the driving force for the anisotropic growth of nanofibers. When NaOH is added during the synthesis, green irregular shaped platelets are obtained, in which the carboxylate groups of benzoate anions are coordinated to the Co(II) ions in a unidentate fashion. Interestingly, the nanofibers exhibit a reversible transformation of the coordination geometry of the Co(II) ions between octahedral and pseudotetrahedral with a concomitant color change between pink and blue, which involves the loss and reuptake of unusual weakly coordinated water molecules without destroying the structure. This work offers a facile, cost-effective, and green strategy to rationally design and synthesize functional nanomaterials for future applications in catalysis, magnetism, gas storage or separation, and sensing technology.

8.
J Mol Model ; 20(7): 2335, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25007917

RESUMO

The trans-2-chlorovinyldichloroarsine (Lewisite) was produced and handled during WWI and WWII as chemical warfare agents. It was very difficult to explore its chemical characterization by experiments ways. The quantum chemical calculations proved to be a precise and harmless method for the toxicological system. In this paper, the gas phase reaction mechanisms of OH radical with trans-2-chlorovinyldichloroarsine (lewisite) were studied by second-order Møller-Plesset perturbation theory (MP2) method. The geometries of reactants, products, complexes, and transition states were optimized at the MP2/6-311++G(d,p) level. To gain more accurate mechanistic knowledge, the single-point energies were calculated using G3 and CCSD(T) method. This reaction exhibited three mechanisms, namely, direct hydrogen abstraction, direct chlorine abstraction, and addition/elimination. Multichannel Rice-Ramsperger-Kassel-Marcus theory and transition-state theory have been carried out for overall and individual rate constants over a wide range of temperatures and pressures. The computational results indicated that addition/elimination reaction is more favorable than direct hydrogen abstraction and direct chlorine abstraction. The major products for the total reaction are AsCl2 and CHClCH2O generated via C(2)-addition/elimination.

9.
Chem Commun (Camb) ; 47(39): 11002-4, 2011 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-21909590

RESUMO

Metal-organic cobalt hydroxide nanorods with controllable dimensions using salicylates as bridging ligands have been synthesized in water under mild conditions in a simple process. The nanorods exhibit a reversible structural transition on dehydration and rehydration with a concomitant color change and may find potential applications in nanodevices.

10.
J Pharm Sci ; 98(11): 3886-902, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19226637

RESUMO

There are many reports in the literature referring to the utilization of drug bound to ion-exchange resin (drug-resinate), especially in the drug delivery area. Ion-exchange resin complexes, which can be prepared from both acidic and basic drugs, have been widely studied and marketed. Salts of cationic and anionic exchange resins are insoluble complexes in which drug release results from exchange of bound drug ions by ions normally present in body fluids. Resins used are polymers that contain appropriately substituted acidic groups, such as carboxylic and sulfonic for cation exchangers; or basic groups, such as quaternary ammonium group for anion exchangers. Variables relating to the resin are the exchange capacity; degree of cross-linking, which determines the permeability of the resin, its swelling potential, and the access of the exchange sites to the drug ion; the effective pK(a) of the exchanging group, which determines the exchange affinity; and the resin particle size, which controls accessibility to the exchange ions. In this review, the properties of ion-exchange resins, selection of drugs that lend themselves to such an approach, selection of the appropriate resin, preparation of drug-resinate, evaluation of drug release, recent developments of drug-resinates, and applications are discussed.


Assuntos
Portadores de Fármacos , Sistemas de Liberação de Medicamentos , Resinas de Troca Iônica/administração & dosagem , Reagentes para Ligações Cruzadas/química , Resinas de Troca Iônica/química , Tamanho da Partícula , Polímeros/química
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