Ana S. Macedo

Current State-of-Art and New Trends on Lipid Nanoparticles (SLN and NLC) for Oral Drug Delivery

Lipids and lipid nanoparticles are extensively employed as oral-delivery systems for drugs and other active ingredients. These have been exploited for many features in the field of pharmaceutical technology. Lipids usually enhance drug absorption in the gastrointestinal tract (GIT), and when formulated as nanoparticles, these molecules improve mucosal adhesion due to small particle size and increasing their GIT residence time. In addition, lipid nanoparticles may also protect the loaded drugs from chemical and enzymatic degradation and gradually release drug molecules from the lipid matrix into blood, resulting in improved therapeutic profiles compared to free drug. Therefore, due to their physiological and biodegradable properties, lipid molecules may decrease adverse side effects and chronic toxicity of the drug-delivery systems when compared to other of polymeric nature. This paper highlights the importance of lipid nanoparticles to modify the release profile and the pharmacokinetic parameters of drugs when administrated through oral route.

Characterization of antibiotic resistant enterococci isolated from untreated waters for human consumption in Portugal.

Untreated drinking water is frequently overlooked as a source of antibiotic resistance in developed countries. To gain further insight on this topic, we isolated the indicator bacteria Enterococcus spp. from water samples collected in wells, fountains and natural springs supplying different communities across Portugal, and characterized their antibiotic resistance profile with both phenotypic and genetic approaches. We found various rates of resistance to seven antibiotic families. Over 50% of the isolates were resistant to at least ciprofloxacin, tetracyclines or quinupristin-dalfopristin and 57% were multidrug resistant to ≥3 antibiotics from different families. Multiple enterococcal species (E. faecalis, E. faecium, E. hirae, E. casseliflavus and other Enterococcus spp) from different water samples harbored genes encoding resistance to tetracyclines, erythromycin or gentamicin [tet(M)-46%, tet(L)-14%, tet(S)-5%, erm(B)-22%, aac(6´)-Ie-aph(2″)-12%] and putative virulence factors [gel-28%, asa1-16%]. The present study positions untreated drinking water within the spectrum of ecological niches that may be reservoirs of or vehicles for antibiotic resistant enterococci/genes. These findings are worthy of attention as spread of antibiotic resistant enterococci to humans and animals through water ingestion cannot be dismissed.

Therapeutic nanosystems for oncology nanomedicine

Cancer is a complex disease which includes many pathologies featuring abnormal growth of healthy cells, invasion and metastization. Cellular uncontrolled growth increases the amount of abnormal cells, these cells reach the blood stream and other healthy tissues giving rise to secondary tumors. Even though great progresses have been made in understanding cancer aetiology and in the development of new anticancer drugs, cancer still remains one of the leading causes of death worldwide. Most common cancers include breast cancer, lung cancer, colorectal cancer and brain cancer. Conventional chemotherapeutics have proven to be inefficient in cancer treatment due to lack of specificity and poor drug accumulation in tumors. In addition, they cause severe side effects. Available treatments must be prolonged on time to achieve some therapeutic effect; however, this often leads to the development of multidrug resistance by tumor cells. Nanotechnology platforms are, therefore, being exploited as potential alternatives. Nanosystems have been reported to target and deliver the drug in situ to selectively kill cancer cells, decreasing toxicity on healthy organs and tissues as well as side effects. Furthermore, some nanosystems have been reported to overcome tumor resistance, at least to some extent. Over the years several nanosystems have been proposed to diagnose and treat cancers, such as dendrimers, polymeric micelles, superparamagnetic iron oxide cores, gold nanoparticles, liposomes and other lipid nanoparticles. Due to their small size and biocompatibility, they can reach the target site without being detected by the immune system and suffer cellular uptake or deliver the drug in the tumor vicinity.

Nanoemulsions for delivery of flavonoids: formulation and in vitro release of rutin as model drug.

Abstract The aim of the present study is to design and characterize a rutin-loaded nanoemulsion (RT-NE) and determine the release profile of the drug in vitro. RT-NE was prepared by a high pressure homogenization technique. The obtained droplets were analyzed by optical microscopy and were shown to be of spherical shape. By dynamic light scattering, characterization of RT-NE showed an average diameter of 127 nm, polydispersity index of 0.168 and zeta potential values near neutrality (−3.49 mV). Encapsulation efficiency was of ∼82% (82.3 ± 1.62%). Drug release was characterized by an initial burst which decreased over the time, showing a sustained release profile. After 24 h, rutin released from NE reached nearly 65%. The developed system proved to be stable and suitable to encapsulating poorly water-soluble drugs.