1,720,973 research outputs found
Mathematical modelling of drug release from microemulsions: theory in comparison with experiments
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Acyclovir permeation through rat skin: mathematical modelling and in vitro experiments
No full textAbstract The aim of this work is to characterise the skin permeation properties of a male rat by means of a purely diffusive mathematical model based on Fick's second law. Additionally, in the attempt of proposing a reliable tool allowing the skin permeability (or resistance) determination on the basis of experimental data, the model automatically accounts also for two typical experimental conditions. In particular, drug dissolution in the donor environment and receiver sampling technique (part of the receiver volume is withdrawn and immediately replaced by fresh solvent) are considered. The results of this characterisation are then compared with those coming from a common simplified approach. Acyclovir is chosen as model drug and a thermostatic (37 • C) Franz cell apparatus is used to perform permeation experiments. This study suggests that Acyclovir permeation through the rat skin can be well described by the proposed model and that some differences arise in the evaluation of the full-skin resistance performed by means of our model or the usual simpler approach
Biphasic multicomponent pharmaceutical dosage forms containing substances able to modify the partitioning of drugs
No full textThe present invention refers to a drug multicomponent biphasical composition that enables to solve the problems of prior art
Permeazione di acyclovir attraverso la mucosa intestinale di ratto: esperimenti in vitro e modellizzazione matematica
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Theoretical and experimental analysis of drug release from an ensemble of polymeric particles containing amorphous and nano-crystalline drug
No full textThe analysis of the release kinetics from a delivery system containing amorphous and/or nano-crystalline drug requires the evaluation of many parameters among which the water solubility of the amorphous/nano-crystalline drug is one of the most important. This, in turn, needs the determination of the drug melting enthalpy/temperature dependence on the curvature radius of the crystalline phase (thought, for the sake of simplicity, of spherical shape). Accordingly, this paper is aimed to develop a general theoretical approach devoted to model the melting enthalpy/temperature variation with nano-crystals radius, the solubility dependence on nano-crystals radius and the release process from an ensemble of polymeric particles (crosslinked polyvinylpyrrolidone) containing a poorly water soluble drug (nimesulide) in its amorphous and nano-crystalline status. Drug loading was achieved by means of drug and polymer co-grinding. This study allowed the determination of the nanocrystals fraction and size distribution in the co-ground systems, the drug solubility increase of nano-crystals and the estimation of amorphous drug solubility. This approach yielded to the conclusion that, in the case of nimesulide, a significant increase of solubility occurs for the amorphous form and for nanocrystals characterised by radii lower than 4 nm
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