1,721,026 research outputs found
Drug delivery to retinal photoreceptors
Full text linkThe photoreceptors of the retina are afflicted by diseases that still often lack satisfactory treatment options. Although suitable drugs might be available in some cases, the delivery of these compounds into the eye and across the blood–retinal barrier remains a significant challenge for therapy development. Here, we review the routes of drug administration to the retina and highlight different options for drug delivery to the photoreceptor cells
Dexamethasone-cyclodextrin-chitosan nanoparticles
No full textTrabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014Cyclodextrins are oligosaccharides that have been studied for over 100 years and they have been used in numerous industries, ranging from food or cosmetic to pharmaceutical industry. However, some of them are still regarded as novel pharmaceutical excipients.
Their characteristics make them particularly interesting since they can form complexes with poorly-water soluble lipophilic drugs, enhancing its water solubility. This strategy may improve the drugs oral bioavailability and their permeability through biological membranes.
One of the interesting areas of research in drug delivery is the design of nanomedicines consisting of nanosystems that are able to deliver drugs to the right place, at appropriate time. Natural polysaccharides have received more and more attention in this field and they seem to be very promising materials in the preparation of nanometric carriers.
The main goal of the present study was to develop dexamethasone nanoparticles using a polymer (chitosan) and an anionic cyclodextrin, sulfobutylether-β-cyclodextrin, and investigate its characteristics.
The results obtained reveal that it is possible to form NPs consisting of those components, and they also show that the NPs present good proprieties such as stability at room temperature.As Ciclodextrinas são oligossacáridos que têm vindo a ser estudadas há mais de 100 anos e são usadas em inúmeras indústrias, desde a indústria alimentar ou cosmética até à indústria farmacêutica. Contudo, muitas delas ainda são encaradas como excipientes farmacêuticos novos.
As suas características tornam-nas particularmente interessantes, uma vez que podem formar complexos com fármacos lipofílicos, melhorando a sua solubilidade em água. E assim, melhoram a biodisponibilidade dos fármacos e influenciam a sua permeabilidade através das membranas biológicas.
Uma das áreas de investigação na administração de fármacos é o design de nanomedicamentos que consistam em nanosistemas com capacidade para fazer o fármaco chegar ao local de acção no período adequado. Polissacáridos naturais têm recebido cada vez mais atenção nesta área e perecem ser materiais muito promissores na preparação de transportadores à escala nano.
O objectivo principal deste estudo é desenvolver nanopartículas de dexametasona, usando um polímero (quitosano) e uma ciclodextrina aniónica, a sulfobutileter- β-ciclodextrina, e investigar as suas características.
Os resultados demonstraram que é possível criar NPs que consistam nestes componentes, e ainda revelam que as NPs formadas apresentam boas propriedades, tal como a estabilidade à temperatura ambiente
Dexamethasone-cyclodextrin-chitosan nanoparticles
No full textTrabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014Cyclodextrins are oligosaccharides that have been studied for over 100 years and they have been used in numerous industries, ranging from food or cosmetic to pharmaceutical industry. However, some of them are still regarded as novel pharmaceutical excipients.
Their characteristics make them particularly interesting since they can form complexes with poorly-water soluble lipophilic drugs, enhancing its water solubility. This strategy may improve the drugs oral bioavailability and their permeability through biological membranes.
One of the interesting areas of research in drug delivery is the design of nanomedicines consisting of nanosystems that are able to deliver drugs to the right place, at appropriate time. Natural polysaccharides have received more and more attention in this field and they seem to be very promising materials in the preparation of nanometric carriers.
The main goal of the present study was to develop dexamethasone nanoparticles using a polymer (chitosan) and an anionic cyclodextrin, sulfobutylether-β-cyclodextrin, and investigate its characteristics.
The results obtained reveal that it is possible to form NPs consisting of those components, and they also show that the NPs present good proprieties such as stability at room temperature.As Ciclodextrinas são oligossacáridos que têm vindo a ser estudadas há mais de 100 anos e são usadas em inúmeras indústrias, desde a indústria alimentar ou cosmética até à indústria farmacêutica. Contudo, muitas delas ainda são encaradas como excipientes farmacêuticos novos.
As suas características tornam-nas particularmente interessantes, uma vez que podem formar complexos com fármacos lipofílicos, melhorando a sua solubilidade em água. E assim, melhoram a biodisponibilidade dos fármacos e influenciam a sua permeabilidade através das membranas biológicas.
Uma das áreas de investigação na administração de fármacos é o design de nanomedicamentos que consistam em nanosistemas com capacidade para fazer o fármaco chegar ao local de acção no período adequado. Polissacáridos naturais têm recebido cada vez mais atenção nesta área e perecem ser materiais muito promissores na preparação de transportadores à escala nano.
O objectivo principal deste estudo é desenvolver nanopartículas de dexametasona, usando um polímero (quitosano) e uma ciclodextrina aniónica, a sulfobutileter- β-ciclodextrina, e investigar as suas características.
Os resultados demonstraram que é possível criar NPs que consistam nestes componentes, e ainda revelam que as NPs formadas apresentam boas propriedades, tal como a estabilidade à temperatura ambiente
Dexamethasone-cyclodextrin-chitosan nanoparticles
No full textTrabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014Cyclodextrins are oligosaccharides that have been studied for over 100 years and they have been used in numerous industries, ranging from food or cosmetic to pharmaceutical industry. However, some of them are still regarded as novel pharmaceutical excipients.
Their characteristics make them particularly interesting since they can form complexes with poorly-water soluble lipophilic drugs, enhancing its water solubility. This strategy may improve the drugs oral bioavailability and their permeability through biological membranes.
One of the interesting areas of research in drug delivery is the design of nanomedicines consisting of nanosystems that are able to deliver drugs to the right place, at appropriate time. Natural polysaccharides have received more and more attention in this field and they seem to be very promising materials in the preparation of nanometric carriers.
The main goal of the present study was to develop dexamethasone nanoparticles using a polymer (chitosan) and an anionic cyclodextrin, sulfobutylether-β-cyclodextrin, and investigate its characteristics.
The results obtained reveal that it is possible to form NPs consisting of those components, and they also show that the NPs present good proprieties such as stability at room temperature.As Ciclodextrinas são oligossacáridos que têm vindo a ser estudadas há mais de 100 anos e são usadas em inúmeras indústrias, desde a indústria alimentar ou cosmética até à indústria farmacêutica. Contudo, muitas delas ainda são encaradas como excipientes farmacêuticos novos.
As suas características tornam-nas particularmente interessantes, uma vez que podem formar complexos com fármacos lipofílicos, melhorando a sua solubilidade em água. E assim, melhoram a biodisponibilidade dos fármacos e influenciam a sua permeabilidade através das membranas biológicas.
Uma das áreas de investigação na administração de fármacos é o design de nanomedicamentos que consistam em nanosistemas com capacidade para fazer o fármaco chegar ao local de acção no período adequado. Polissacáridos naturais têm recebido cada vez mais atenção nesta área e perecem ser materiais muito promissores na preparação de transportadores à escala nano.
O objectivo principal deste estudo é desenvolver nanopartículas de dexametasona, usando um polímero (quitosano) e uma ciclodextrina aniónica, a sulfobutileter- β-ciclodextrina, e investigar as suas características.
Os resultados demonstraram que é possível criar NPs que consistam nestes componentes, e ainda revelam que as NPs formadas apresentam boas propriedades, tal como a estabilidade à temperatura ambiente
Cyclodextrins in eye drop formulations: enhanced topical delivery of corticosteroids to the eye
No full textNeðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenCyclodextrins are cylindrical oligosaccharides with a lipophilic central cavity and hydrophilic outer surface. They can form water-soluble complexes with lipophilic drugs, which 'hide' in the cavity. Cyclodextrins can be used to form aqueous eye drop solutions with lipophilic drugs, such as steroids and some carbonic anhydrase inhibitors. The cyclodextrins increase the water solubility of the drug, enhance drug absorption into the eye, improve aqueous stability and reduce local irritation. Cyclodextrins are useful excipients in eye drop formulations of various drugs, including steroids of any kind, carbonic anhydrase inhibitors, pilocarpine, cyclosporins, etc. Their use in ophthalmology has already begun and is likely to expand the selection of drugs available as eye drops. In this paper we review the properties of cyclodextrins and their application in eye drop formulations, of which their use in the formulation of dexamethasone eye drops is an example. Cyclodextrins have been used to formulate eye drops containing corticosteroids, such as dexamethasone, with levels of concentration and ocular absorption which, according to human and animal studies, are many times those seen with presently available formulations. Cyclodextrin-based dexamethasone eye drops are well tolerated in the eye and seem to provide a higher degree of bioavailability and clinical efficiency than the steroid eye drop formulations presently available. Such formulations offer the possibility of once per day application of corticosteroid eye drops after eye surgery, and more intensive topical steroid treatment in severe inflammation. While cyclodextrins have been known for more than a century, their use in ophthalmology is just starting. Cyclodextrins are useful excipients in eye drop formulations for a variety of lipophilic drugs. They will facilitate eye drop formulations for drugs that otherwise might not be available for topical use, while improving absorption and stability and decreasing local irritation
Effect of hydrocortisone presence in aggregates size in cyclodextrin aqueous solutions
No full textTrabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014Cyclodextrins are oligosaccharides that have been extensively used in several industries, ranging from the food industry to the pharmaceutical industry. However, despite they have been studied for over 100 years, they are still regarded as novel pharmaceutical excipients. Cyclodextrins are particularly interesting because of their ability to form inclusion complexes with poorly-water soluble drugs and so to increase drug solubility and bioavailability. There are several routes for drug delivery by cyclodextrins (oral, sublingual, ocular, nasal, pulmonary, parenteral and dermic) and all of them have been carefully studied and improved in order to obtain safe formulations for human administration. It is known that cyclodextrins can form aggregates amongst each other in aqueous solutions, both as free molecule or when taking part in an inclusion complex. Although, it is not well comprehended yet what forces drive the aggregates formation or which shape or size it can present. It is also necessary to investigate its stability and safety. The work here presented was centered in the observation of the behavior of α- and β-cyclodextrins complexes with the objective to understand the differences between aggregates formed at specific environmental conditions, its stability and whether the presence of a drug influences the aggregate formation.As Ciclodextrinas são oligossacarídeos que têm sido utilizados nas mais variadas indústrias, desde a alimentar à indústria farmacêutica. Contudo, apesar de terem vindo a ser estudadas durante os últimos 100 anos, ainda são encaradas como novos excipientes farmacêuticos. Possuem particular interesse devido à sua capacidade de formar complexos de inclusão com fármacos pouco solúveis em água, permitindo assim aumentar a sua solubilidade e biodisponibilidade. Permitem também a veiculação dos fármacos por várias vias (oral, sublingual, ocular, nasal, pulmonar, intravenosa e dérmica) e todas elas foram cuidadosamente estudadas para se obterem formulações seguras para administração. Sabe-se que as ciclodextrinas formam agregados em soluções aquosas, tanto na forma livre como na forma de complexo de inclusão. No entanto, ainda não são bem conhecidas as forças que motivam o processo de agregação nem quais as formas e dimensões que os agregados podem apresentar. É também necessário compreender a sua estabilidade e segurança. O trabalho aqui apresentado foca-se na observação do comportamento de complexos de α- e β-ciclodextrinas com o objectivo de entender as diferenças entre agregados formados a várias condições experimentais específicas, a sua estabilidade e, por fim, se a presença do fármaco influencia ou não a formação de agregados.The work herein presented was developed under the ERASMUS protocol between the University of Lisbon and the University of Iceland from March 2013 to June 2013. All experimental procedures were carried out in the laboratories of the Pharmaceutical Sciences Department of the University of Iceland
Effect of hydrocortisone presence in aggregates size in cyclodextrin aqueous solutions
No full textTrabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014Cyclodextrins are oligosaccharides that have been extensively used in several industries, ranging from the food industry to the pharmaceutical industry. However, despite they have been studied for over 100 years, they are still regarded as novel pharmaceutical excipients. Cyclodextrins are particularly interesting because of their ability to form inclusion complexes with poorly-water soluble drugs and so to increase drug solubility and bioavailability. There are several routes for drug delivery by cyclodextrins (oral, sublingual, ocular, nasal, pulmonary, parenteral and dermic) and all of them have been carefully studied and improved in order to obtain safe formulations for human administration. It is known that cyclodextrins can form aggregates amongst each other in aqueous solutions, both as free molecule or when taking part in an inclusion complex. Although, it is not well comprehended yet what forces drive the aggregates formation or which shape or size it can present. It is also necessary to investigate its stability and safety. The work here presented was centered in the observation of the behavior of α- and β-cyclodextrins complexes with the objective to understand the differences between aggregates formed at specific environmental conditions, its stability and whether the presence of a drug influences the aggregate formation.As Ciclodextrinas são oligossacarídeos que têm sido utilizados nas mais variadas indústrias, desde a alimentar à indústria farmacêutica. Contudo, apesar de terem vindo a ser estudadas durante os últimos 100 anos, ainda são encaradas como novos excipientes farmacêuticos. Possuem particular interesse devido à sua capacidade de formar complexos de inclusão com fármacos pouco solúveis em água, permitindo assim aumentar a sua solubilidade e biodisponibilidade. Permitem também a veiculação dos fármacos por várias vias (oral, sublingual, ocular, nasal, pulmonar, intravenosa e dérmica) e todas elas foram cuidadosamente estudadas para se obterem formulações seguras para administração. Sabe-se que as ciclodextrinas formam agregados em soluções aquosas, tanto na forma livre como na forma de complexo de inclusão. No entanto, ainda não são bem conhecidas as forças que motivam o processo de agregação nem quais as formas e dimensões que os agregados podem apresentar. É também necessário compreender a sua estabilidade e segurança. O trabalho aqui apresentado foca-se na observação do comportamento de complexos de α- e β-ciclodextrinas com o objectivo de entender as diferenças entre agregados formados a várias condições experimentais específicas, a sua estabilidade e, por fim, se a presença do fármaco influencia ou não a formação de agregados.The work herein presented was developed under the ERASMUS protocol between the University of Lisbon and the University of Iceland from March 2013 to June 2013. All experimental procedures were carried out in the laboratories of the Pharmaceutical Sciences Department of the University of Iceland
Stabilization and solubilization of difluprednate in aqueous cyclodextrin solution and its characterization for ophthalmic delivery
Full text linkPublisher´s version / Útgefin greinDifluprednate is a synthetic glucocorticoid used for the treatment of postoperative inflammation and pain
associated with endogenous uveitis. It is very lipophilic with limited aqueous solubility and stability. The only
available marketed formulation is an oil-in-water ophthalmic emulsion that has many drawbacks. Cyclodextrin
(CD) molecules are widely used to increase the solubility and stability of hydrophobic drugs through the for-
mation of drug/CD complexes. This study aims to investigate degradation kinetics, stability and solubility of
difluprednate in aqueous CD solutions in an effort to develop aqueous eye drop vehicle for ophthalmic delivery.
Phase-solubility and kinetics studies were performed in presence of different CDs and polymers. Characterization
of the drug/CD complexes was done using techniques like NMR, DSC, and FTIR. The results show that diflu-
prednate has maximum stability at pH 5 in aqueous CD solution. HPγCD was found to be the best solubilizer and
stabilizer among all the CDs tested. The stability was further improved with the combination of HPγCD and
different polymers. Characterization of the difluprednate/HPγCD complex in solid and solution state confirmed
the presence of a drug/CD complex. It was possible to solubilize 0.1% difluprednate using HPγCD and stabilize
the drug using combination of CD and polymer in aqueous solutionThis work was financially supported by the European Union grant
no. MSCA-ITN-2017-765441 (transMed) and the Faculty of Pharmaceutical Sciences, University of Iceland.Peer-Reviewe
The Stokes-Einstein equation and the physiological effects of vitreous surgery [editorial]
No full textTo access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldRemoval of the vitreous humour influences the physiology of the eye. The diffusion characteristics of small molecules in the vitreous cavity are changed dramatically by the removal of vitreous gel and its replacement by aqueous humour. This effect is predicted by the Stokes−Einstein equation (Sinko 2006). In vitrectomy the vitreous gel is replaced by water. As vitreous humour is 99% water, the chemical change is not terribly great, but there is an enormous change in viscosity. All liquids possess a definitive resistance to flow; viscosity is a measure of internal flow friction or the resistance of liquid molecules. The higher the magnitude of viscosity, the more resistant the liquid will be to flow. The viscosity of water is 1.00 centipoise (cp) at 20 °, whereas that of vitreous gel is 300–2000 cp (Lee et al. 1992; Soman & Banerjee 2003). The change in viscosity has a major effect on diffusion and thereby on the transport of all substances through the vitreous cavity. The amount (M) of compound flowing through a unit cross-section (S) of a flow barrier in unit time (t) is known as the flux (J)
Effect of hydrocortisone presence in aggregates size in cyclodextrin aqueous solutions
No full textTrabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014Cyclodextrins are oligosaccharides that have been extensively used in several industries, ranging from the food industry to the pharmaceutical industry. However, despite they have been studied for over 100 years, they are still regarded as novel pharmaceutical excipients. Cyclodextrins are particularly interesting because of their ability to form inclusion complexes with poorly-water soluble drugs and so to increase drug solubility and bioavailability. There are several routes for drug delivery by cyclodextrins (oral, sublingual, ocular, nasal, pulmonary, parenteral and dermic) and all of them have been carefully studied and improved in order to obtain safe formulations for human administration. It is known that cyclodextrins can form aggregates amongst each other in aqueous solutions, both as free molecule or when taking part in an inclusion complex. Although, it is not well comprehended yet what forces drive the aggregates formation or which shape or size it can present. It is also necessary to investigate its stability and safety. The work here presented was centered in the observation of the behavior of α- and β-cyclodextrins complexes with the objective to understand the differences between aggregates formed at specific environmental conditions, its stability and whether the presence of a drug influences the aggregate formation.As Ciclodextrinas são oligossacarídeos que têm sido utilizados nas mais variadas indústrias, desde a alimentar à indústria farmacêutica. Contudo, apesar de terem vindo a ser estudadas durante os últimos 100 anos, ainda são encaradas como novos excipientes farmacêuticos. Possuem particular interesse devido à sua capacidade de formar complexos de inclusão com fármacos pouco solúveis em água, permitindo assim aumentar a sua solubilidade e biodisponibilidade. Permitem também a veiculação dos fármacos por várias vias (oral, sublingual, ocular, nasal, pulmonar, intravenosa e dérmica) e todas elas foram cuidadosamente estudadas para se obterem formulações seguras para administração. Sabe-se que as ciclodextrinas formam agregados em soluções aquosas, tanto na forma livre como na forma de complexo de inclusão. No entanto, ainda não são bem conhecidas as forças que motivam o processo de agregação nem quais as formas e dimensões que os agregados podem apresentar. É também necessário compreender a sua estabilidade e segurança. O trabalho aqui apresentado foca-se na observação do comportamento de complexos de α- e β-ciclodextrinas com o objectivo de entender as diferenças entre agregados formados a várias condições experimentais específicas, a sua estabilidade e, por fim, se a presença do fármaco influencia ou não a formação de agregados.The work herein presented was developed under the ERASMUS protocol between the University of Lisbon and the University of Iceland from March 2013 to June 2013. All experimental procedures were carried out in the laboratories of the Pharmaceutical Sciences Department of the University of Iceland
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