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Marlene Lopes
University of Coimbra
BioavailabilityDextranInsulinType 1 diabetesPharmacology
11Publications
6H-index
165Citations
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Publications 11
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#1Marlene Lopes (UC: University of Coimbra)H-Index: 6
#2Barbara Abrahim (UFRJ: Federal University of Rio de Janeiro)H-Index: 3
Last. António J. Ribeiro (IBMC: Instituto de Biologia Molecular e Celular)H-Index: 28
view all 8 authors...
ABSTRACTIntroduction: Alginate-based particles have emerged as one of the most extensively searched drug delivery platforms due to their inherent properties, including good biocompatibility and biodegradability. Moreover, the low price, easy availability, natural origin, versatility and sol-gel transition properties, make alginate an ideal candidate to produce particles with different applications. Several techniques have been developed and optimized to prepare microparticles and nanoparticles i...
16 CitationsSource
#1Marlene Lopes (UC: University of Coimbra)H-Index: 6
#2Denise AnicetoH-Index: 1
Last. António J. Ribeiro (IBMC: Instituto de Biologia Molecular e Celular)H-Index: 28
view all 10 authors...
Abstract This study aimed to assess the biodistribution of antihyperglycemic insulin-loaded alginate/dextran sulfate-based nanoparticles dual coated with chitosan and technetium-99m-albumin ( 99m Tc-BSA) after oral administration. The oral administration of 50 IU/kg insulin-loaded nanoparticles to type 1 diabetic rats showed prolonged antihyperglycemic effects up to 12 h and relative pharmacological availability of 5.04% comparing to the subcutaneous administration. The oral antihyperglycemic ef...
6 CitationsSource
#1Marlene Lopes (UC: University of Coimbra)H-Index: 6
#2Neha Shrestha (UH: University of Helsinki)H-Index: 12
Last. Hélder A. Santos (UH: University of Helsinki)H-Index: 42
view all 10 authors...
The potential of nanoparticles (NPs) to overcome the barriers for oral delivery of protein drugs have led to the development of platforms capable of improving their bioavailability. However, despite the progresses in drug delivery technologies, the success of oral delivery of insulin remains elusive and the disclosure of insulin mechanisms of absorption remains to be clarified. To overcome multiple barriers faced by oral insulin and to enhance the insulin permeability across the intestinal epith...
54 CitationsSource
#1Marlene Lopes (UC: University of Coimbra)H-Index: 6
#2Amelie Derenne (UC: University of Coimbra)H-Index: 1
Last. António J. Ribeiro (IBMC: Instituto de Biologia Molecular e Celular)H-Index: 28
view all 7 authors...
Although the oral administration of insulin is recognized as the safest and most attractive, insulin oral bioavailability is usually reduced due to the susceptibility to acidic and enzymatic degradation in the gastrointestinal (GI) tract and intrinsic low intestinal permeability. Nanoencapsulation of insulin is, thus, foreseen as a promising approach to overcome most of these drawbacks. The effect of the GI environment on the aggregation of alginate/dextran sulfate-based nanometric-sized particl...
6 CitationsSource
Alginate–dextran sulfate-based particles obtained by emulsification/internal gelation technology can be considered suitable carriers for oral insulin delivery. A rational study focused on the emulsification and particle recovery steps was developed in order to reduce particles to the nanosize range while keeping insulin bioactivity. There was a decrease in size when ultrasonication was used during emulsification, which was more pronounced when a cosurfactant was added. Ultrasonication add-on aft...
18 CitationsSource
#1Marlene LopesH-Index: 6
Last. António J. RibeiroH-Index: 28
view all 5 authors...
Oral insulin able to induce an efficient antihyperglycemic effect either to replace or complement diabetes mellitus therapy is the major goal of health providers, governments and diabetic patients. Oral therapy is associated not only with the desire to exclude needles from the daily routine of diabetic patient but also with the physiological provision of insulin they would get. Despite numerous efforts over the past few decades to develop insulin delivery systems, there is still no commercially ...
12 CitationsSource
#1Marlene LopesH-Index: 6
#2Barbara AbrahimH-Index: 3
Last. António J. RibeiroH-Index: 28
view all 6 authors...
Increased interest in alginate-based submicron particles is due to alginate properties, such as low price, easy availability, natural origin, and versatility. Several techniques have been developed and optimized to prepare particles of several size scales. Alginate-based micro- and nanoparticles have many different applications in the fi eld of biotechnology and biomedicine. Their widespread use is essentially due to alginate unique features, namely biocompatibility and biodegradability. This en...
The oral route is the most suitable and physiological delivery route. Oral insulin delivery would minimize the health hazard implied in repeated injection, surpass complications arising from the need for sterile techniques associated with parenteral formulations and provide better glucose homeostasis. However, it is limited by various physiological barriers and still remains a scientific challenge. The desire to deliver insulin by the oral route in a conveniently and effectively way has led to t...
11 CitationsSource
#1Marlene Lopes (UC: University of Coimbra)H-Index: 6
#2Barbara Abrahim (UC: University of Coimbra)H-Index: 3
Last. António J. Ribeiro (UC: University of Coimbra)H-Index: 28
view all 7 authors...
Abstract Nanodelivery systems have been extensively studied as a strategy for the effective treatment of type 1 diabetes in animal models. Nanoparticle formulations have been shown to contribute to increased intestinal absorption of insulin according to established pathways. It is important to determine whether intestinal absorption of the hormone, specifically occurs through a privileged pathway that is favored because of particular properties of the nanoparticles. Confocal fluorescence microsc...
39 CitationsSource
Last. Lucio Mendes CabralH-Index: 19
view all 13 authors...
Aims: Develop an anti-tuberculosis (TB) Fixed Dose Combination (FDC) tablet containing an immediate release layer (IRL) composed of both rifampicin (RIF) and pyrazinamide (PYR) and a retarded release layer (RRL) comprised of isoniazid (INH) which would allow segregated delivery of RIF and INH. Study Design:Trialswere conducted on thepre-formulations andformulationsto assess the compatibilityof excipientsand obtain amodified release profile , for anIRL consisting of bothRIF and PYR and aRRL conta...
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