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Abstract Background and purpose: Recent researches have shown that liquisolid technique is a new and promising method for controlling the dissolution rate of drugs. In this study the effects of Eudragit RS PO and HPMC on theophylline release from liquisolid compacts were evaluated. Materials and methods: Theophylline was dispersed in PEG 200 as the liquid vehicle. Then a binary mixture of carrier coating materials (Eudragit or HPMC as the carrier and silica as coating material with 2:1 ratio) was added to the liquid medication under continuous mixing in a mortar for 10 minutes. The mixture was compressed using the manual tableting machine. After preparing several formulations the release profiles were evaluated. To evaluate any interaction between theophylline and the other components in liquisolid formulations the differential scanning calorimetery (DSC) and FTIR were used. Results: Theophylline tablets prepared by liquisolid technique and contained Eudragit RS PO showed greater retardation properties in comparison with conventional matrix tablets. This investigation provided evidence that PEG 200 has important role in sustaining the release of drug from liquisolid. The kinetic studies revealed that in liquisolid formulations, release kinetic was changed in evaluated formulations containing several polymers. DSC and FTIR showed no complexation between drug and polymer and no change in drug polymorphism. Conclusion: The results showed significant effect of liquisolid technique on the theophylin release rate from related liquisolid systems.

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Background and purpose: The potential of liquisolid systems for increasing drug dissolution has been proved in many researches. Recent studies have shown that liquisolid technique is a new and promising method for controlling the dissolution rate of drugs. Based on thermal treating effect on polymer structure, in this study the effects of thermal treating on theophylline release from liquisolid compacts containing Eudragit RS PO and HPMC (hydroxypropyl methylcellulose) were evaluated. Materials and methods: Theophylline was dispersed in PEG 200 as the liquid vehicle. Then a binary mixture of carrier coating materials (Eudragit or HPMC as the carrier and silica as coating material with 2:1 ratio) was added to the liquid medication under continuous mixing in a mortar for 10 minutes. The mixture was compressed using the manual tableting machine, and then treated in 50, 60, and 70 0C for several periods of times. The release profiles were evaluated. The differential scanning calorimetery (DSC) and fourier transform infrared (FTIR) were used to evaluate any interaction between theophylline and the other components in liquisolid formulations. Results: Thermal treating showed significant decrease in drug release from Eudragit RS containing liquisolid systems. The thermal treating time showed significant effect on theophylline release. This was not observed in liquisolid tablets containing HPMC. DSC and FTIR showed no complexation between drug and polymer and no change in drug polymorphism. Conclusion: The liquisolid technique could be used for design controlled release systems. Thermal treating could affect drug release by affect on polymer structure

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Background and purpose: Despite growing use of energy-saving lamps or compact fluorescent lamps (CFLs), there are concerns about ultraviolet radiation in their output. In this study, the output of CFLs available in Iranian market in the range of infrared, visible, and ultraviolet were measured and the possibility of hydroxyl radical production by their radiation was evaluated.
Materials and methods: The spectrum and light intensity of 33 CFLs were recorded by a spectrometer and radiometers equipped with special infrared, visible, and ultraviolet sensors. The possibility of hydroxyl radical production by three lamps with highest ultraviolet emission intensity was examined and fluorimetric signal of the terephthalic acid dosimeters was evaluated. Parameters such as luminescence efficiency, spectrum integral and the output percentage of lamps were determined in different areas of the spectrum and compared with photopeak curve of human vision.
Results: In lamps with identical powers, there was no significant difference between the intensity of visible and infrared lights. In ultraviolet radiation, the intensity of daylight CFLs was twice as much as soft white CFLs, which had greater intensity compared to incandescent lights.  The infrared intensity in incandescent lamps is ten times more than CFLs. The chemical dosimetry showed that lamps produced by three manufacturers were able to generate hydroxyl radicals in short distances and during long radiations.
Conclusion: CFLs’ radiation is considered to be safe at more than one meter distance. However, at shorter distances and long exposures, some lamps may cause damage to eyes and skin due to ultraviolet radiation. Therefore, it is recommended to monitor specifications of CFLs released into the market.