A Broad-Host-Range Tailocin from Burkholderia cenocepacia.

The Burkholderia cepacia complex (Bcc) consists of 20 closely related Gram-negative bacterial species that are significant pathogens for persons with cystic fibrosis (CF). Some Bcc strains are highly transmissible and resistant to multiple antibiotics, making infection difficult to treat. A tailocin (phage tail-like bacteriocin), designated BceTMilo, with a broad host range against members of the Bcc, was identified in B. cenocepacia strain BC0425. Sixty-eight percent of Bcc representing 10 species and 90% of non-Bcc Burkholderia strains tested were sensitive to BceTMilo. BceTMilo also showed killing activity against Pseudomonas aeruginosa PAO1 and derivatives. Liquid chromatography-mass spectrometry analysis of the major BceTMilo proteins was used to identify a 23-kb tailocin locus in a draft BC0425 genome. The BceTMilo locus was syntenic and highly similar to a 24.6-kb region on chromosome 1 of B. cenocepacia J2315 (BCAL0081 to BCAL0107). A close relationship and synteny were observed between BceTMilo and Burkholderia phage KL3 and, by extension, with paradigm temperate myophage P2. Deletion mutants in the gene cluster encoding enzymes for biosynthesis of lipopolysaccharide (LPS) in the indicator strain B. cenocepacia K56-2 conferred resistance to BceTMilo. Analysis of the defined mutants in LPS biosynthetic genes indicated that an α-d-glucose residue in the core oligosaccharide is the receptor for BceTMilo.IMPORTANCE BceTMilo, presented in this study, is a broad-host-range tailocin active against Burkholderia spp. As such, BceTMilo and related or modified tailocins have potential as bactericidal therapeutic agents against plant- and human-pathogenic Burkholderia.

Screening methodologies for the development of spray-dried amorphous solid dispersions.

PURPOSE: To present a new screening methodology intended to be used in the early development of spray-dried amorphous solid dispersions. METHODS: A model that combines thermodynamic, kinetic and manufacturing considerations was implemented to obtain estimates of the miscibility and phase behavior of different itraconazole-based solid dispersions. Additionally, a small-scale solvent casting protocol was developed to enable a fast assessment on the amorphous stability of the different drug-polymer systems. Then, solid dispersions at predefined drug loads were produced in a lab-scale spray dryer for powder characterization and comparison of the results generated by the model and solvent cast samples. RESULTS: The results obtained with the model enabled the ranking of the polymers from a miscibility standpoint. Such ranking was consistent with the experimental data obtained by solvent casting and spray drying. Moreover, the range of optimal drug load determined by the model was as well consistent with the experimental results. CONCLUSIONS: The screening methodology presented in this work showed that a set of amorphous formulation candidates can be assessed in a computer model, enabling not only the determination of the most suitable polymers, but also of the optimal drug load range to be tested in laboratory experiments. The set of formulation candidates can then be further fine-tuned with solvent casting experiments using a small amount of API, which will then provide the decision for the final candidate formulations to be assessed in spray drying experiments.

Process Optimization and Upscaling of Spray-Dried Drug-Amino acid Co-Amorphous Formulations.

The feasibility of upscaling the formulation of co-amorphous indomethacin-lysine from lab-scale to pilot-scale spray drying was investigated. A 2² full factorial design of experiments (DoE) was employed at lab scale. The atomization gas flow rate (Fatom, from 0.5 to 1.4 kg/h) and outlet temperature (Tout, from 55 to 75 °C) were chosen as the critical process parameters. The obtained amorphization, glass transition temperature, bulk density, yield, and particle size distribution were chosen as the critical quality attributes. In general, the model showed low Fatom and high Tout to be beneficial for the desired product characteristics (a co-amorphous formulation with a low bulk density, high yield, and small particle size). In addition, only a low Fatom and high Tout led to the desired complete co-amorphization, while a minor residual crystallinity was observed with the other combinations of Fatom and Tout. Finally, upscaling to a pilot scale spray dryer was carried out based on the DoE results; however, the drying gas flow rate and the feed flow rate were adjusted to account for the different drying chamber geometries. An increased likelihood to achieve complete amorphization, because of the extended drying chamber, and hence an increased residence time of the droplets in the drying gas, was found in the pilot scale, confirming the feasibility of upscaling spray drying as a production technique for co-amorphous systems.

In Vitro-In Vivo Correlations of Carbamazepine Nanodispersions for Application in Formulation Development.

During formulation development, efficiently integrating in vitro dissolution testing can significantly improve one's ability to estimate in vivo performance and aide in the selection of premier drug candidates. The concept of in vitro-in vivo relationship/correlation has garnered significant attention from pharmaceutical scientists to predict expected bioavailability characteristics for drug substances and products. The present work illustrates a comparative evaluation of in vitro tests to access crystalline carbamazepine and various types of amorphous and crystalline dispersions of carbamazepine and Eudragit® L100 produced by spray drying, including a membrane-permeation dissolution methodology and nonsink dissolution. To establish the best model, parameters such as pH, membrane constitution, and dissolution media composition were investigated. The in vitro results were compared against in vivo mice pharmacokinetic studies and qualitatively, the membrane-permeation dissolution methodology correlated well with in vivo. Various correlations were performed in order to evaluate the optimal model for characterizing the relationship. Results exhibited a coefficient of determination (R2) values of 0.90 and 1.00, depicting a linear relationship of the data in comparison. Therefore, for the current formulation system (drug/polymer/technique), membrane-permeation dissolution can guide formulation development and potentially reduce the number of animal and clinical pharmacokinetic studies required.

Green production of cocrystals using a new solvent-free approach by spray congealing.

Pharmaceutical cocrystals are used as a strategy to overcome poor physicochemical properties of drugs. The use of cocrystals in the pharmaceutical industry remains to be fully exploited due, in part, to the scarcity of suitable large-scale production methods and lack of robust and cost-effective processes. To overcome these challenges, spray congealing was used for the first time in the preparation of cocrystals. The work considered a feasibility study, followed by a design of experiments to assess the impact of varying atomization and cooling-related process parameters on cocrystal formation, purity, particle size, shape and bulk powder flow properties. It was demonstrated that spray congealing could be used to produce cocrystals. The thermal analysis and X-ray results of the spray-congealed products were different from the pure components or physical mixtures and were aligned with those reported for the same cocrystals systems produced by other techniques. Cocrystal particles were compact and spherical consisting of aggregates of individual cocrystals entangled or adhered with each other. From the design of experiments, the results demonstrated that varying the process parameters did not influence cocrystal formation, but had an impact on cocrystal purity. Moreover, it was demonstrated that cocrystal particle properties can be adjusted, in situ, by varying atomization and cooling efficiency, in order to produce particles more suited for incorporation in final dosage forms such as tablets.

Thermal analysis, X-ray powder diffraction and electron microscopy data related with the production of 1:1 Caffeine:Glutaric Acid cocrystals.

The data presented in this article are related to the production of 1:1 Caffeine:Glutaric Acid cocrystals as part of the research article entitled "Green production of cocrystals using a new solvent-free approach by spray congealing" (Duarte et al., 2016) [1]. More specifically, here we present the thermal analysis and the X-ray powder diffraction data for pure Glutaric Acid, used as a raw material in [1]. We also include the X-ray powder diffraction and electron microscopy data obtained for the 1:1 Caffeine:Glutaric Acid cocrystal (form II) produced using the cooling crystallization method reported in "Operating Regions in Cooling Cocrystallization of Caffeine and Glutaric Acid in Acetonitrile" (Yu et al., 2010) [2]. Lastly, we show the X-ray powder diffraction data obtained for assessing the purity of the 1:1 Caffeine:Glutaric cocrystals produced in [1].

Production of nano-solid dispersions using a novel solvent-controlled precipitation process - Benchmarking their in vivo performance with an amorphous micro-sized solid dispersion produced by spray drying.

A novel solvent controlled precipitation (SCP) process based on microfluidization was assessed to produce solid dispersions of carbamazepine, a poorly water-soluble drug with dissolution-rate limited absorption. A half-factorial design (2(3-1)+2 central points) was conducted to study the effect of different formulation variables (viz. polymer type, drug load, and feed solids' concentration) on the particle size and morphology, drug's solid state and drug's molecular distribution within the carrier of the co-precipitated materials produced. Co-precipitated powders were isolated via spray drying (SD). Nano-composite aggregated particles were obtained among all the tests. The particle size of the aggregates was dependent on the feed solids' concentration, while the level of aggregation between nanoparticles was dependent on the drug-polymer ratio. Both amorphous and crystalline nano-solid dispersions were produced using the proposed SCP process. The solid dispersion produced was dependent on both the type of polymeric stabilizer chosen and the drug load. Controls of amorphous and crystalline nano-solid dispersions produced by SCP and an amorphous micro-solid dispersion produced by SD were tested for: in vitro dissolution, in vivo pharmacokinetics in mice, and long-term storage physical stability. Both nano-amorphous and nano-crystalline presented faster dissolution rates and enhanced bioavailabilities than the micro-sized amorphous powder. The reduction of particle size to the nano-scale was found to be more important than the amorphization of the drug. The long-term physical stability of the amorphous nano-solid dispersion and the amorphous micro-solid dispersion were comparable.