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- In vitro behaviour of konjac glucomannan microparticles aimed at pulmonary tuberculosis therapyPublication . Guerreiro, Filipa; Swedrowska, Magda; Rosa Da Costa, Ana; Grenha, Ana; Forbes, BenTuberculosis is one of the highest causes of death worldwide. Long periods of treatment are required and result in some cases in therapeutic incompliance, potentiating the development of multidrug-resistant tuberculosis. Thus, new approaches to treat the infection are required as an alternative to conventional orally administered treatment. This work proposes the development of an inhalable system, which is specifically targeted to alveolar macrophages, where the Mycobacterium tuberculosis is located. The targeting is mainly driven by the selected matrix material, konjac glucomannan (KGM), a natural polymer comprising mannan units that are expected to potentiate phagocytosis. Microparticles were loaded with two antitubercular drugs, isoniazid (INH) and rifabutin (RFB). KGM/INH/RFB microparticles were produced by spray-drying to produce particles with suitable characteristics to deliver INH and RFB to the alveolar region. The KGM/INH/RFB microparticles possessed an aerodynamic diameter of approximately 3 µm, meeting the requirement of a therapy targeted to alveolar macrophages. Moreover, KGM microparticles exhibited suitable geometric size (2.24 µm) and shape (spherical) to be phagocytosed to deliver drugs to infected macrophages. INH and RFB were associated with KGM microparticles with efficiencies of 91% and 74%, respectively. Similar in vitro release profiles were observed for both drugs in simulated lung fluid (SLF) replicating the lining fluid composition found in human alveoli.
- Sulphated locust bean gum-coated lipid nanocapsules as potential lung delivery carriersPublication . Pontes, Jorge Filipe; Braz, L.; Guerreiro, Filipa; Rosa Da Costa, Ana; Almouazen, Eyad; Lollo, Giovanna; Grenha, AnaDrugs pertaining to Biopharmaceutics Classification System (BCS) classes II and IV have limitations in their delivery, including in the lung. Therefore, drug delivery carriers have been proposed to improve the therapeutic effectiveness of such drugs. This work proposes lipid nanocapsules (LNC) as a potential platform for lung drug delivery. Locust bean gum (LBG), which is a galactomannan, was used as polymeric shell, protecting the oily core of the nanocapsules and providing their surface with hydrophilic character. Due to the neutral character of LBG, in order to enable nanocapsule formation, a sulphate derivative (LBGS) was prepared, which was confirmed by Fourier-transformed infrared (FTIR) spectroscopy. The electrostatic interaction between the negatively charged sulphate groups of LBGS and the positively charged groups of the used cationic lipid (1,2-dioleoyloxy-3- trimethylammoniumpropanchloride, DOTAP), allowed the formation of monodisperse nanocapsules, with sizes around 200 nm and strongly negative zeta potentials, between -70 and -85 mV. Envisaging potential lung drug delivery, the LBGS-coated LNC were co-formulated with mannitol using spray-drying, producing microencapsulated nanocapsules. Feret’s diameter was determined to be 2.6 ± 1.8 µm and 3.1 ± 1.9 µm for Man (control) and Man/LNC microparticles, respectively. Further studies are underway in order to optimise both the nanoplatform and the dry powder formulation.
- Dual antibiotherapy of tuberculosis mediated by inhalable locust bean gum microparticlesPublication . Rodrigues, Susana; Alves, Ana D.; Cavaco, Joana S.; Pontes, Jorge Filipe; Guerreiro, Filipa; Rosa Da Costa, Ana; Buttini, Francesca; Grenha, AnaDespite the existence of effective oral therapy, tuberculosis remains a deadly pathology, namely because of bacterial resistance and incompliance with treatments. Establishing alternative therapeutic approaches is urgently needed and inhalable therapy has a great potential in this regard. As pathogenic bacteria are hosted by alveolar macrophages, the co-localisation of antitubercular drugs and pathogens is thus potentiated by this strategy. This work proposes inhalable therapy of pulmonary tuberculosis mediated by a single locust bean gum (LBG) formulation of microparticles associating both isoniazid and rifabutin, complying with requisites of the World Health Organisation of combined therapy. Microparticles were produced by spray-drying, at LBG/INH/RFB mass ratio of 10/1/0.5. The aerodynamic characterisation of microparticles revealed emitted doses of more than 90% and fine particle fraction of 38%, thus indicating the adequacy of the system to reach the respiratory lung area, thus partially the alveolar region. Cytotoxicity results indicate moderate toxicity (cell viability around 60%), with a concentration-dependent effect. Additionally, rat alveolar macrophages evidenced preferential capture of LBG microparticles, possibly due to chemical composition comprising mannose and galactose units that are specifically recognised by macrophage surface receptors. (C) 2017 Elsevier B.V. All rights reserved.
- Microencapsulation of selenium by spray-drying as a tool to improve bioaccessibility in food matrixPublication . Grenha, Ana; Guerreiro, Filipa; Lourenço, João P.; Lopes, João Almeida; Cámara-Martos, FernandoSe in the form of sodium selenite was microencapsulated by spray - drying and added to a food matrix (yogurt) to study the potential improvement of its bioaccessibility. Yogurt samples were also supplemented with Se in free salt form. Se-loaded microparticles were successfully prepared by spray-drying with production yields above 70%. The supplementation of yogurt with Se in the form of free sodium selenite had a low effect on improving the bioaccessibility of this micronutrient (1%). In turn, Se microencapsulation with mannitol or mannitol/gastro-resistant polymer (Eudragit (R)) had a strong impact on bioaccessibility results. After the gastric phase, Se bio-accessibility reached values of 21 and 40% for the microencapsulated formulations, respectively. This percentage rose to 55% at the end of intestinal phase, showing no differences between both formulations. Our results show the relevance of microencapsulation as an effective tool to improve the bioaccessibility of micronutrients when they are used in food supplementation.
- Inhalable locust bean gum microparticles co-associating isoniazid and rifabutin: therapeutic assessment in a murine model of tuberculosis infectionPublication . Grenha, Ana; Alves, Ana D.; Guerreiro, Filipa; Pinho, Jacinta; Simões, Sandra; Almeida, António José; Gaspar, Maria ManuelaTuberculosis is a leading cause of death worldwide. Although the development of new antimycobacterial drugs is an obvious and necessary strategy to address the disease, improving the therapeutic performance of drugs already approved constitutes a valuable alternative approach. As the lung is the most affected organ, where M. tuberculosis is able to survive and proliferate, the direct pulmonary delivery of antitubercular drugs comprises a highly promising therapeutic strategy. In this work, spray-dried locust bean gum (LBG) microparticles were used to deliver a combination of two first line antitubercular drugs, isoniazid (INH) and rifabutin (RFB), to the alveolar zone, where macrophages hosting the bacteria reside. LBG is expected to mediate favoured macrophage uptake of microparticles, leading to enhanced therapeutic effect. The therapeutic effect of LBG/INH/RFB microparticles was evaluated in a murine model infected with M. tuberculosis, strain H37Rv and compared with oral co-therapy of INH and RFB in the free form. The pulmonary administration of LBG/INH/RFB microparticles 5 times per week was the only treatment schedule that provided negative growth index values in lung (-0.22), spleen (-0.14) and liver (-0.26) even using a lower therapeutic dose for both antibiotics. For the control group, the respective values were +1.95, +0.75 and +0.96.
- Spray-drying of konjac glucomannan to produce microparticles for an application as antitubercular drug carriersPublication . Guerreiro, Filipa; Pontes, Jorge Filipe; Rosa Da Costa, Ana; Grenha, AnaSpray-drying is proposed in this work as the technique to produce konjac glucomannan microparticles aimed at an application in lung tuberculosis therapy. Microparticles were developed to provide direct lung delivery of an association of two first-line antitubercular drugs, isoniazid and rifabutin, by inhalation. Mannitol or leucine were incorporated as spray-drying excipients to verify their effect on the final properties of drug-loaded konjac glucomannan microparticles. The obtained results indicate that konjac glucomannan is a suitable material for the preparation of inhalable microparticles for antitubercular therapy upon processing by spray-drying. The incorporation of excipients revealed no benefit on the characterised properties. Isoniazid and rifabutin were mostly associated to microparticles with success (efficiencies of 88-104%). However, the presence of mannitol was found to decrease the capacity to associate isoniazid (efficiency of 43%). The excipients further promoted the acceleration of drug release. Moreover, general absence of toxicity was observed for microparticles in Calu-3 and A549 cells, with cell viabilities above 70%. The results of the work suggest that microparticles composed only of KGM display the most appropriate characteristics.
- Inhalable antitubercular therapy mediated by locust bean gum microparticlesPublication . Alves, Ana; Cavaco, Joana; Guerreiro, Filipa; Lourenço, J. P.; Costa, Ana M. Rosa da; Grenha, AnaTuberculosis remains a major global health problem and alternative therapeutic approaches are needed. Considering the high prevalence of lung tuberculosis (80% of cases), the pulmonary delivery of antitubercular drugs in a carrier system capable of reaching the alveoli, being recognised and phagocytosed by alveolar macrophages (mycobacterium hosts), would be a significant improvement to current oral drug regimens. Locust bean gum (LBG) is a polysaccharide composed of galactose and mannose residues, which may favour specific recognition by macrophages and potentiate phagocytosis. LBG microparticles produced by spray-drying are reported herein for the first time, incorporating either isoniazid or rifabutin, first-line antitubercular drugs (association efficiencies >82%). Microparticles have adequate theoretical properties for deep lung delivery (aerodynamic diameters between 1.15 and 1.67 μm). The cytotoxic evaluation in lung epithelial cells (A549 cells) and macrophages (THP-1 cells) revealed a toxic effect from rifabutin-loaded microparticles at the highest concentrations, but we may consider that these were very high comparing with in vivo conditions. LBG microparticles further evidenced strong ability to be captured by macrophages (percentage of phagocytosis >94%). Overall, the obtained data indicated the potential of the proposed system for tuberculosis therapy.
- Spray-dried polysaccharide microparticles aimed at pulmonary delivery of antitubercular drugsPublication . Guerreiro, Filipa Raquel Horta; Grenha, AnaMicroparticles (MPs) of konjac glucomannan (KGM) are proposed in this thesis as an alternative therapeutic approach for antitubercular drug delivery to the lung, in the ambit of tuberculosis (TB) therapy. KGM is composed of mannose groups that might comprise an entry mechanism in macrophages infected with Mycobacterium tuberculosis, mimicking one of the input paths of this infectious agent causer of TB. For this purpose, KGM MPs need to have certain properties, in particular an aerodynamic diameter between 1 and 3 μm that enables reaching the alveolar zone. These properties might be attained by a production using spray-drying technology. The objective of this work was to produce MPs of KGM through this process and associate two first-line antitubercular drugs, isoniazid (INH) and rifabutin (RFB). Furthermore, the effect of incorporating mannitol or leucine in the microparticle formulations was evaluated, regarding MPs aerodynamic characteristics, drug association and release, and biocompatibility profile. After an initial optimization that required a hydrolysis of the original KGM polymer to enable spray-drying, several formulations of MPs were produced and characterised. The use of mannitol or leucine has demonstrated to improve the flow properties of some formulations, as did the association of RFB. However, the incorporation of excipients brought some disadvantages, especially regarding the in vitro release rate of the drug, which became faster. Additionally, the incorporation of mannitol was found to affect the association of INH, which became lower, suggesting a competing effect between INH and mannitol. Cytotoxicity assays in alveolar epithelial cells revealed that RFB-loaded KGM MPs may have a considerably toxic effect when used at a concentration of 1 mg/mL, in particular if MPs are also comprised of leucine. The obtained results indicate that KGM MPs are suitable inhalable delivery systems for antitubercular drugs. Considering that a combination of drugs is advised by WHO in TB treatment, no benefit was found to occur from the incorporation of either leucine or mannitol in the formulation of KGM MPs.
- Respirable konjac glucomannan microparticles as antitubercular drug carriers: Effects of in vitro and in vivo interactionsPublication . Guerreiro, Filipa; Pontes, Jorge Filipe; Gaspar, Maria Manuela; Rosa Da Costa, Ana; Faleiro, Maria Leonor; Grenha, AnaPulmonary delivery of drugs is potentially beneficial in the context of lung disease, maximising drug concentrations in the site of action. A recent work proposed spray-dried konjac glucomannan (KGM) microparticles as antitubercular drug (isoniazid and rifabutin) carriers to treat pulmonary tuberculosis. The present work explores in vitro and in vivo effects of these microparticles, focusing on the ability for macrophage uptake, the exhibited antibacterial activity and safety issues. Efficient uptake of KGM microparticles by macrophages was demonstrated in vitro, while the antitubercular activity of the model drugs against Mycobacterium bovis was not affected by microencapsulation in KGM microparticles. Despite the good indications provided by the developed system, KGM is not yet approved for pulmonary applications, which is a limiting characteristic. To reinforce the available data on the performance of the material, safety parameters were evaluated both in vitro and in vivo, showing promising results. No significant cell toxicity was observed at concentrations considered realistic for lung delivery approaches (up to 125 & mu;g/mL) when lung epithelial cells and macrophages were exposed to KGM microparticles (both drug-loaded and unloaded). Finally, no signs of systemic or lung inflammatory response were detected in mice after receiving 10 administrations of unloaded KGM microparticles.
- Engineering of konjac glucomannan into respirable microparticles for delivery of antitubercular drugsPublication . Guerreiro, Filipa; Swedrowska, Magda; Patel, Roshnee; Floréz- Fernández, Noelia; Torres, María Dolores; Rosa Da Costa, Ana M.; Forbes, Ben; Grenha, AnaFew medically-approved excipients are available for formulation strategies to endow microcarriers with improved performance in lung drug targeting. Konjac glucomannan (KGM) is a novel, biocompatible material, comprising mannose units potentially inducing macrophage uptake for the treatment of macrophage-mediated diseases. This work investigated spray-dried KGM microparticles as inhalable carriers of model antitubercular drugs, isoniazid (INH) and rifabutin (RFB). The polymer was characterised and different polymer/drug ratios tested in the production of microparticles for which respirability was assessed in vitro. The swelling of KGM microparticles and release of drugs in simulated lung fluid were characterised and the biodegradability in presence of beta-mannosidase, a lung hydrolase, determined. KGM microparticles were drug loaded with 66-91% association efficiency and had aerodynamic diameter around 3 mu m, which enables deep lung penetration. The microparticles swelled upon liquid contact by 40-50% but underwent size reduction (>62% in 90 min) in presence of beta-mannosidase, indicating biodegradability. Finally, drug release was tested showing slower release of RFB compared with INH but complete release of both within 24 h. This work identifies KGM as a biodegradable polymer of natural origin that can be engineered to encapsulate and release drugs in respirable microparticles with physical and chemical macrophage-targeting properties.