Effect of gamma radiation on amlodis and its potential for radiosterilization
In the present work, radiation sensitivity of amlodis (AML) and its active ingredient Amlodipin Besylate (AML-B) were separately investigated by electron spin resonance (ESR) spectroscopy using radiolytic products induced in these drugs. Irradiation in the dose range of 2.5-25kGy did not create any ESR resonance line in AML-B, but it create five characteristic ESR resonance lines associated with more than one radical species in the case of AML. This signal is attributed to the radical species created upon irradiation of inactive ingredients such as microcrystalline cellulose and sodium starch glycolate of AML. Five resonance lines were observed to be divided into three sub groups of different characteristic behaviors associable with three different radical species. Radical species responsible from observed ESR lines were unstable at room and above room temperatures, however, they conserved their identities over a storage period of 92 days. This permitted to discriminate irradiated AML from unirradiated one. A quadratic function was found to describe best the variations of the intensities of observed resonance lines with applied radiation dose. A model based on three tentative radical species with a pyranose ring formed by the rapture of CH bonds in positions 1 and 4 was proposed to explain the observed five lines experimental ESR spectra. AML was considered not providing the characteristic features of a good dosimetric material due to its low radiation yield and relatively fast decays of the created radical species, but very low radiation sensitivity of its active ingredient, namely AML-B makes AML a good candidate for radiosterilization.
Available from: Hasan Tuner
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ABSTRACT: In the present work, the effects of gamma radiation on solid butylated hydroxytoluene (BHT), which is used as an antioxidant, were investigated by ESR spectroscopy. While unirradiated BHT presented no ESR signal, irradiated BHT exhibited an ESR spectrum with many resonance maxima and minima spread over a magnetic field range of 12 mT and centered at about g = 2.0026. Weak satellite and central intense resonance lines, likely, originated from radical species of different stabilities and ratios were observed to be responsible from experimental ESR spectrum of gamma irradiated BHT. Studies based on the variations of the observed line intensities and spectrum area under different experimental conditions were carried out and characteristic features of the radical species responsible from experimental ESR spectrum were determined. Mesomeric radical species of different stabilities providing to BHT a G value of 0.25 were believed to be induced in gamma irradiated BHT. While species responsible from weak satellite lines were unstable, the species causing central intense lines were found to be relatively stable. BHT belongs to a class of compounds with low radiosensitivity (G = 0.25). This feature of BHT enables the feasibility of radiosterilizations of the products containing BHT as antioxidant without very much loss from its antioxidant benefit. BHT has been shown to provide an opportunity in the estimation of applied radiation dose with a reasonable accuracy if an appropriate mathematical function is used to describe experimental dose-response data.
Available from: Mine Silindir Gunay
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ABSTRACT: The interaction of radiation, whether it has natural or artificial, electromagnetic or particle-type characterizations, with materials causes different effects depending on the dose and type of radiation and physicochemical properties of the material. In the medical field, understanding the effect of radiation on a variety of materials including pharmaceuticals, medical devices, polymers as biomaterials, and packaging is crucial. Although there are many kinds of sterilization methods, the use of radiation in sterilization has many advantages such as being a substantially less toxic, safer terminal sterilization method. Radiosterilization is sterilization with an ionizing radiation such as gamma rays or electron beam (e-beam), the latter being a newer but less-frequently used technique. However, the need for large facilities with proper radiation protections for personnel and the environment from the effects of radiation and radioactive wastes makes this procedure highly costly. The effects of radiation on materials, especially pharmaceuticals and polymer-containing medical devices, cause degradation or chemical changes. The effects of radiation on a variety of different materials is a growing research area that can create safer techniques that reduce radiation damage and increase cost-effectiveness in the future.
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ABSTRACT: Both in the pharmaceutical industry and in pharmacology, crystallization and dissolution processes play an important role in the production and physiological action of active pharmaceutical ingredients. For the first, recrystallization or other phase transformations present an indispensable step in downstream separation and purification processing, while for the second, solubility is of vital importance for drug delivery systems such as tablets. In the present study, the anhydrous form of amlodipine was investigated from its basic structural and conformational characteristics using molecular modeling, to the laboratory-scale formation of its solid phase from solution, and finally, to industrial-size operation by applying models, based on the hydrodynamic characteristics in the crystallizer due to mixing (computational fluid dynamics (CFD)), transport phenomena (specifically heat transfer), and population balance modeling. Simulations revealed that an efficient process intensification and control may be realized through the seeding and widening of the metastable zone (nucleus absence albeit supersaturation), providing a uniform and monodisperse size distribution.
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