Long-acting injectable donepezil microspheres: Formulation development and evaluation.

Novel formulations of donepezil (DNP)-loaded microspheres based on a bio-degradable polymer of poly(lactic-co-glycolic acid) (PLGA) with a one-month duration of effect were developed, aimed at reducing dosing frequency and adverse effects and improving patient adherence. The spherical and monodispersed DNP-loaded microspheres were precisely fabricated by the Inventage Lab Precision Particle Fabrication method (IVL-PPFM®) based on micro-electromechanical systems (MEMS) and microfluidic technology. The types of polymers and end-groups, the drug/polymer ratio (DPR), and the routes of administration for DNP were studied to ensure an effective concentration and desired duration. Laser-light particle size analysis and scanning electron microscopy were used to characterization. Also, non-clinical animal models of beagle dogs are used to optimize DNP formulations and evaluate their pharmacokinetic properties. The PK results showed that the DPR was a critical factor in determining the exposure level and duration of DNR release. Furthermore, the lactide ratio, which varied depending upon the type of polymer, determined the hydrophobic interaction and was also an important factor affecting the desired DNP release. Since DNP shows a large inter-species variation between dogs and humans, PK modeling and simulation of the reference drug (i.e., Aricept®) and DNP-loaded microspheres were used for formulation development to overcome and interpret these variations. In addition, the developed PK model was extrapolated to humans using the estimated PK parameter and published clinical pharmacology data for DNP. The predicted PK profile of the DNP-loaded microsphere in humans showed that the formulation with PLGA 7525A and the DPR of 1/9 could maintain drug concentration for a month and could control initial burst release. The data obtained from the study could be used as scientific evidence for decision-making in future formulation development.

Comparative Evaluation of Safety and Efficacy of a Novel Hyaluronic Acid-polynucleotide/Poly-L-lactic Acid Composite Dermal Filler.

BACKGROUND: Poly-L-lactic acid (PLLA) is widely used in tissue engineering. The natural polymer hyaluronic acid (HA) shows excellent biocompatibility and affects cell signaling, proliferation, and differentiation. In addition, a polynucleotide (PN) induces cell growth of human skin fibroblasts and osteoblasts. OBJECTIVE: In this study, we evaluated the properties, safety, and efficacy of a novel composite filler consisting of cross-linked HA with PN in combination with monodisperse PLLA microspheres manufactured using Inventage Lab Precision Particle Fabrication method. MATERIALS AND METHODS: The composition of the filler and characteristics of the microspheres were examined via scanning electron microscopy, particle size analysis, gel permeation chromatography, and rheology and osmolality measurement. Additionally, safety and efficacy of HA-PN/PLLA composite filler were conducted in in vitro and in vivo. RESULTS: Analysis of PLLA microspheres revealed spherical surfaces and a narrower particle size distribution than that in PLLA filler. HA-PN/PLLA composite filler had higher viscosity and elasticity values and similar osmolality as compared to those of HA and PN fillers. The nontoxicity in in vitro and in vivo tests reflected that the composite filler may be safe for human use. In addition, the composite filler maintained a more stable volume than did HA filler for 24 weeks after administration in HWY/Slc hairless rats. Furthermore, the results support the effect of HA-PN/PLLA in restoring skin structure. CONCLUSION: Altogether, these data suggest that the novel composite filler might be a safe and effective option in terms of tissue integration, clinical management during delivery and high esthetic durability. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Analysis of 16S rRNA and mxaF genes revealing insights into Methylobacterium niche-specific plant association.

The genus Methylobacterium comprises pink-pigmented facultative methylotrophic (PPFM) bacteria, known to be an important plant-associated bacterial group. Species of this group, described as plant-nodulating, have the dual capacity of producing cytokinin and enzymes, such as pectinase and cellulase, involved in systemic resistance induction and nitrogen fixation under specific plant environmental conditions. The aim hereby was to evaluate the phylogenetic distribution of Methylobacterium spp. isolates from different host plants. Thus, a comparative analysis between sequences from structural (16S rRNA) and functional mxaF (which codifies for a subunit of the enzyme methanol dehydrogenase) ubiquitous genes, was undertaken. Notably, some Methylobacterium spp. isolates are generalists through colonizing more than one host plant, whereas others are exclusively found in certain specific plant-species. Congruency between phylogeny and specific host inhabitance was higher in the mxaF gene than in the 16S rRNA, a possible indication of function-based selection in this niche. Therefore, in a first stage, plant colonization by Methylobacterium spp. could represent generalist behavior, possibly related to microbial competition and adaptation to a plant environment. Otherwise, niche-specific colonization is apparently impelled by the host plant.

Analysis of 16S rRNA and mxaF genes reveling insights into Methylobacterium niche-specific plant association

The genus Methylobacterium comprises pink-pigmented facultative methylotrophic (PPFM) bacteria, known to be an important plant-associated bacterial group. Species of this group, described as plant-nodulating, have the dual capacity of producing cytokinin and enzymes, such as pectinase and cellulase, involved in systemic resistance induction and nitrogen fixation under specific plant environmental conditions. The aim hereby was to evaluate the phylogenetic distribution of Methylobacterium spp. isolates from different host plants. Thus, a comparative analysis between sequences from structural (16S rRNA) and functional mxaF (which codifies for a subunit of the enzyme methanol dehydrogenase) ubiquitous genes, was undertaken. Notably, some Methylobacterium spp. isolates are generalists through colonizing more than one host plant, whereas others are exclusively found in certain specific plant-species. Congruency between phylogeny and specific host inhabitance was higher in the mxaF gene than in the 16S rRNA, a possible indication of function-based selection in this niche. Therefore, in a first stage, plant colonization by Methylobacterium spp. could represent generalist behavior, possibly related to microbial competition and adaptation to a plant environment. Otherwise, niche-specific colonization is apparently impelled by the host plant.

Genetic and metabolic diversity of pink-pigmented facultative methylotrophs in phyllosphere of tropical plants

Diversity of Pink-Pigmented Facultative Methylotrophs (PPFMs) in phyllosphere of cotton, maize and sunflower was determined based on differential carbon-substrate utilization profile and Random Amplified Polymorphic DNA data. Results indicate that six diversified groups of PPFMs are found in these crops. Sunflower and maize phyllosphere harbor four different groups of methylobacteria while cotton has only two groups.

A diversidade de microrganismos metilotróficos facultativos pigmentados (PPFMs) na filosfera de algodão, milho e girassol foi determinada baseada no perfil diferencial de utilização de substratos de carbono e em dados de RAPD. Os resultados indicaram a existência de seis grupos diferentes de PPFMs nessas plantas. As filosferas de girassol e milho apresentaram quatro grupos diferentes de metilobactérias enquanto a de algodão apresentou apenas dois grupos.

Genetic and metabolic diversity of pink-pigmented facultative methylotrophs in phyllosphere of tropical plants.

Diversity of Pink-Pigmented Facultative Methylotrophs (PPFMs) in phyllosphere of cotton, maize and sunflower was determined based on differential carbon-substrate utilization profile and Random Amplified Polymorphic DNA data. Results indicate that six diversified groups of PPFMs are found in these crops. Sunflower and maize phyllosphere harbor four different groups of methylobacteria while cotton has only two groups.