Generation of curcumin-loaded albumin nanoparticles by using off-the-shelf microfluidics driven by gravity.

The generation albumin-based nanocarriers by precipitation from solution has great interest in the formulation of advanced nutritional products. Microfluidic techniques enable the implementation of low energy and continuum processes, with fast mass transfer and homogeneous mixing at the microscale. Here we describe the microfluidic generation of curcumin-loaded alpha lactalbumin nanoparticles in a simple and inexpensive way, by using off-the-shelf devices designed to produce solvent-shifting nanoprecipitation in core-sheath flows driven by gravity, which has not been reported before. Nanoparticles were characterized by dynamic light scattering, electron microscopy, and infrared spectroscopy. The microfluidic operating conditions were defined by theory and experiments, and the critical parameters controlling the nanoparticles diameter were identified. The prepared nanoparticles resulted practically monodisperse, the curcumin entrapment efficiency was about 40 %, and almost 70 % of the bioactive was gradually delivered in release experiments. The proposed methodology is a promising route to scale up the microfluidic elaboration of nanoparticles for the entrapment of active ingredients.

Progesterone loaded thermosensitive hydrogel for vaginal application: Formulation and in vitro comparison with commercial product.

Progesterone (PGT) is a natural hormone that stimulates and regulates various important functions, such as the preparation of the female body for conception and pregnancy. Due to its low water solubility, it is administered in a micronized form and/or in vehicles with specific solvents requirements. In order to improve the drug solubility, inclusion complexes of PGT and ß-cyclodextrins were obtained by the freeze-drying method. Two ß-cyclodextrins (native and methylated) in two solvents (water and water:ethanol) and different molar ratio of the reagents were the variables tested for the selection of the best condition for the preparation of the complexes. The PGT/randomly methylated-ß-cyclodextrin complexes were incorporated into chitosan thermosensitive hydrogels, as an alternative formulation for the vaginal administration of PGT. Neither the micro and macroscopic characteristics of the gels nor the transition time from solution to gel were modified after the complexes incorporation. In addition, chitosan gels with complexes resisted better the degradation in simulated vaginal fluid in comparison to commercial gel (Crinone®). The chitosan gel with inclusion complexes and Crinone® were tested in vitro in a diffusion assay to evaluate the delivery of the hormone and its diffusion through porcine epithelial mucosa obtained from vaginal tissue. Chitosan gel presented sustained diffusion similar to the exhibited by commercial gel. The use of chitosan gels with inclusion complexes based on cyclodextrins would be a viable alternative for vaginal administration of PGT.

Paclitaxel/ß-Cyclodextrin interactions, a perspective from pulsed NMR spectroscopy experiments.

Cyclodextrins are cyclic cone shaped oligosaccharides. A guest molecule can be incorporated into the hydrophobic inner of the cyclodextrin to form non-covalent complexes. The formation of these complexes in general, increases the solubility, stability, dissolution rate, and bioavailability of drugs with poor water solubility. Different techniques were applied to gain insights about the interaction between paclitaxel and randomly methylated-ß-cyclodextrin during the formation of an inclusion complex. Results from infrared spectroscopy, differential scanning calorimetry, nuclear magnetic resonance and scanning electron microscopy were compared. The fast and economical pulsed nuclear magnetic resonance spectroscopy allows to explain that mol paclitaxel:mol RAMEß-CD 1:20 was the best ratio to obtain inclusion complexes. In addition, the preferred aromatic ring for the inclusion is that in the position 3' of the side chain of paclitaxel molecule.

Paclitaxel delivery system based on poly(lactide-co-glycolide) microparticles and chitosan thermo-sensitive gel for mammary adenocarcinoma treatment.

OBJECTIVES: To evaluate the combination of more than one release system in the same formulation as a useful strategy to achieve paclitaxel delivery in a more sustained and controlled manner. METHODS: The present study deals with the preparation of poly(lactide-co-glycolide) microparticles loaded with paclitaxel and included in a chitosan thermo-sensitive gelling solution. The microparticles were characterized by their size, shape and drug loading. The formulation was characterized by scanning electron microscopy, in vitro release experiments and was evaluated in mice bearing mammary adenocarcinoma. KEY FINDINGS: The formation of paclitaxel crystals in a pharmaceutical formulation reduces its efficacy. In this work, the use of microparticles avoided this phenomenon. Combining more than one delivery system allowed delivering paclitaxel in a more sustained and controlled manner leading to a long-term effect in the site of action. The formulation showed an inhibition in tumour volume of 63.0% in comparison with the control group. CONCLUSIONS: One intratumour injection of gelling solution containing the microparticles was at least as efficacious as four intraperitoneal injections of a commercial formulation. In addition, the delivery system was nontoxic, and the treated mice presented the highest percentage of tumour regression and median survival time.

In vitro evaluation of suspoemulsions for in situ-forming polymeric microspheres and controlled release of progesterone.

One possibility to obtain a higher dose of drug in a lower formulation volume can be by using of saturated quantity of drug in one of the phases of an emulsion. These formulations are called suspoemulsions (S/O/W). When a hydrophobic polymer is added to the organic phase of suspoemulsions, these formulations can be used to entrap the drug inside microspheres after in situ precipitation of the polymer-drug-excipients mix. In this work, performance and stability of progesterone suspensions in triacetin as organic phase of suspoemulsions were evaluated. These formulations were compared with O/W emulsions. Mathematical models were used to study in vitro release profiles. The results confirmed that S/O/W systems could be an attractive alternative to O/W formulations for the entrapment of progesterone inside poly(d,l-lactide-co-glycolide) microspheres. Diffusive-based models fit the in vitro release of progesterone from in situ-formed microspheres. For longer release periods, a time-dependent diffusion coefficient was successfully estimated.

Recent advances in chitosan films for controlled release of drugs.

Chitosan is a versatile carrier for biologically active agent from a small molecule such as an antibiotic to macromolecules such as proteins and nucleic acids. In addition, drug delivery devices based on chitosan can be available in a variety of morphologies including films, fibers, nanoparticles and microspheres. Otherwise the inherent advantages of this polymer such as biocompatibility, tissue adhesions and hydrophilic nature, chitosan can be modified to accomplish a specific purpose, for example improves release kinetics. In this review, recent patents of chitosan-based film systems for drug delivery are presented and discussed. This review include matrix type systems, membrane coated systems and film forming solution. For each one of these systems, several examples of manufacture processes, bioactive agents to be delivered and specifics applications are considered. This work highlights the use of chitosan in the film technology for drug delivery, presenting examples of chitosan used in an unmodified state and examples of modifications of the polymer backbone.

Evaluation of rapid alternative methods for drug susceptibility testing in clinical isolates of Mycobacterium tuberculosis.

A study was carried out to compare the performance of a commercial method (MGIT) and four inexpensive drug susceptibility methods: nitrate reductase assay (NRA), microscopic observation drug susceptibility (MODS) assay, MTT test, and broth microdilution method (BMM). A total of 64 clinical isolates of Mycobacterium tuberculosis were studied. The Lowenstein-Jensen proportion method (PM) was used as gold standard. MGIT NRA, MODS, and MTT results were available on an average of less than 10 days, whereas BMM results could be reported in about 20 days. Most of the evaluated tests showed excellent performance for isoniazid and rifampicin, with sensitivity and specificity values > 90%. With most of the assays, sensitivity for ethambutol was low (62-87%) whereas for streptomycin, sensitivity values ranged from 84 to 100%; NRA-discrepancies were associated with cultures with a low proportion of EMB-resistant organisms while most discrepancies with quantitative tests (MMT and BMM) were seen with isolates whose minimal inhibitory concentrations fell close the cutoff MGIT is reliable but still expensive. NRA is the most inexpensive and easiest method to perform without changing the organization of the routine PM laboratory performance. While MODS, MTT, and BMM, have the disadvantage from the point of view of biosafety, they offer the possibility of detecting partial resistant strains. This study shows a very good level of agreement of the four low-cost methods compared to the PM for rapid detection of isoniazid, rifampicin and streptomycin resistance (Kappa values > 0.8); more standardization is needed for ethambutol.

Evaluation of rapid alternative methods for drug susceptibility testing in clinical isolates of Mycobacterium tuberculosis

A study was carried out to compare the performance of a commercial method (MGIT) and four inexpensive drug susceptibility methods: nitrate reductase assay (NRA), microscopic observation drug susceptibility (MODS) assay, MTT test, and broth microdilution method (BMM). A total of 64 clinical isolates of Mycobacterium tuberculosis were studied. The Lowenstein-Jensen proportion method (PM) was used as gold standard. MGIT, NRA, MODS, and MTT results were available on an average of less than 10 days, whereas BMM results could be reported in about 20 days. Most of the evaluated tests showed excellent performance for isoniazid and rifampicin, with sensitivity and specificity values > 90 percent. With most of the assays, sensitivity for ethambutol was low (62-87 percent) whereas for streptomycin, sensitivity values ranged from 84 to 100 percent; NRA-discrepancies were associated with cultures with a low proportion of EMB-resistant organisms while most discrepancies with quantitative tests (MMT and BMM) were seen with isolates whose minimal inhibitory concentrations fell close the cutoff. MGIT is reliable but still expensive. NRA is the most inexpensive and easiest method to perform without changing the organization of the routine PM laboratory performance. While MODS, MTT, and BMM, have the disadvantage from the point of view of biosafety, they offer the possibility of detecting partial resistant strains. This study shows a very good level of agreement of the four low-cost methods compared to the PM for rapid detection of isoniazid, rifampicin and streptomycin resistance (Kappa values > 0.8); more standardization is needed for ethambutol.