Kotaro Iida’s research while affiliated with Meijo University and other places

An attempt was made to produce carrier particles for dry powder inhalation with lactose carrier particles surface-coated using a Wurster fluidized bed. The lactose carrier particles were coated with lactose aqueous solution containing hydroxypropyl methyl cellulose (HPMC) as a binder using a Wurster coating apparatus. Drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers under various particle surface conditions. These powder mixtures were aerosolized by a Jethaler((R)), and the in vitro deposition properties of salbutamol sulfate were evaluated by a twin impinger. The in vitro inhalation properties of the powder mixture prepared using the coated lactose carrier differed significantly compared with those of the powder mixture prepared using the uncoated lactose carrier, indicating improvements in in vitro inhalation properties of sulbutamol sulfate. In vitro inhalation properties increased with the surface coating time. This surface coating system would thus be valuable for increasing the in vitro inhalation properties of dry powder inhalation with lactose carrier particles.

The present study examined the stability of a gene in powders prepared with supercritical carbon dioxide (CO(2)) from the viewpoints of the ternary structure of DNA and in vivo transfection potential. An aqueous chitosan-pCMV-Luc complex solution containing mannitol was injected into the stream of a supercritical CO(2)/ethanol admixture to precipitate a gene powder. The obtained gene powders and gene solutions were placed in stability chambers at 25 or 40 degrees C for 4 weeks. The integrity and transfection potency of the gene were examined by electrophoresis and in vivo pulmonary transfection study in mice. The supercritical CO(2) process decreased the supercoiled DNA during the manufacturing process; however, the decrease in the remaining supercoiled and open circular DNA in the powders during storage was much slower than that in solutions. In addition, the powders had higher transfection potency than the solutions containing the same amount of DNA. The effect of chitosan on the stability of DNA in solutions was not obvious in the solutions but it improved the stability of DNA in powders during manufacturing and storage. Thus, a gene powder with a cationic vector is a promising ready-to-use formulation for inhalation therapy of pulmonary diseases.

The effects of the surface processing of lactose carrier particles on the dry powder inhalation properties of salbutamol sulfate were investigated. Lactose carrier particles were processed using a high-speed elliptical-rotor-type powder mixer (Theta-Composer). In the present study, drug/carrier powder mixtures were prepared, consisting of micronized salbutamol sulfate and coarse lactose carriers with various particle surface conditions prepared by surface processing. These powder mixtures were aerosolized by a Jethaler, and the in vitro inhalation properties of salbutamol sulfate were evaluated with a twin impinger. Compared with those of the powder mixed with unprocessed lactose carriers, the in vitro inhalation properties of the powder mixture prepared using the surface processed lactose carriers were significantly different, showing that the in vitro inhalation properties of salbutamol sulfate were improved. The in vitro inhalation properties increased with the rotor rotation rate. Using this surface processing system would thus be valuable for increasing the inhalation properties of dry powder inhalation with lactose carrier particles.

The influence of storage humidity on the in vitro inhalation properties of salbutamol sulfate dry powder with surface covered lactose carrier was investigated. In the present study, drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers with different particle surface conditions prepared by surface covering. Lactose carrier surfaces were covered with vegetable magnesium stearate (Mg-St-V) by a high-speed elliptical-rotor-type powder mixer (Theta-Composer). These powder mixtures were aerosolized by a Jethaler), and the in vitro inhalation properties of salbutamol sulfate were evaluated by a twin impinger. Compared with the powder mixed with uncovered lactose carrier, the in vitro inhalation properties of the powder mixture prepared using the surface covered lactose carrier were little decreased with increased in relative humidity (RH), showing that the in vitro inhalation properties of salbutamol sulfate were improved at high RH. Using this surface covering technique would thus be valuable for storage humidity of dry powder inhalation (DPI) with lactose carrier particles.

The effect of pulmonary absorption enhancers on the stability of active ingredients is an important factor for successful inhalation therapy as well as the effect on pharmacological activity and safety. We examined the effect of pulmonary absorption enhancers on the stability of insulin in dry powders prepared by a spray-drying technique. Although the hypoglycemic effect was greatly improved when a dry insulin powder containing citric acid (MIC SD) was administered, insulin in the MIC SD was unstable compared with the other powders examined. Bacitracin and Span 85, which are potent pulmonary absorption enhancers of insulin formulated in solutions, showed no deteriorative effect on the stability of dry insulin powder. However, they did not improve the hypoglycemic effect of insulin in dry powders. We modified the insulin dosage form with citric acid to improve the insulin stability at room temperature without loss of hypoglycemic activity. MIC Mix was formulated as a combination of insulin powder (MI') and citric acid powder (MC). MIC Mix showed hypoglycemic activity comparable to MIC SD while the insulin stability was much better than that of MIC SD at a 60 degrees C/dry condition. However, moisture lowered the insulin stability and changed the particle morphology of MIC Mix with time at a 60 degrees C/75% relative humidity condition, suggesting that a package preventing moisture absorption was necessary for the MIC Mix powder.

The effect of the surface layering time of lactose carrier particles on the dry powder inhalation properties of salbutamol sulfate was investigated. Lactose carrier particles were layered with vegetable magnesium stearate by physical mixing. In the present study, drug/carrier powder mixtures were designed consisting of micronized salbutamol sulfate and lactose carriers with various particle surface conditions prepared by surface layering. These powder mixtures were aerosolized by a Jethaler, and the in vitro deposition properties of salbutamol sulfate were evaluated by a twin impinger. Compared with the powder mixed with unlayered lactose carrier, the in vitro inhalation properties of the powder mixture prepared using the surface layering lactose carrier were significantly different, showing that the in vitro inhalation properties of the drug/carrier powder mixtures were improved. In vitro deposition properties (RP) increased with surface layering time. Using this surface layering system would thus be valuable for increasing the inhalation properties of dry powder inhalation.

The effect of the surface covering of lactose carrier particles on the dry powder inhalation properties of salbutamol sulfate was investigated. Lactose carrier surfaces were covered with sucrose tristearate (J-1803F) by a high-speed elliptical-rotor-type powder mixer (Theta-Composer). In the present study, drug/carrier powder mixtures were prepared consisting of micronized salbutamol sulfate and lactose carriers with various particle surface conditions prepared by surface covering. These powder mixtures were aerosolized by a Jethaler), and the in vitro inhalation properties of salbutamol sulfate were evaluated by a twin impinger. Compared with the powder mixed with uncovered lactose carrier, the in vitro inhalation properties of the powder mixture prepared using the surface covering lactose carrier were significantly different, showing that the in vitro inhalation properties of salbutamol sulfate were improved. In vitro inhalation properties increased with the percentage of J-1803F added. Using this surface covering system would thus be valuable for increasing the inhalation properties of dry powder inhalation with lactose carrier particles.

The purpose of this study was to improve insulin absorption from dry powder after administration in lung without an absorption enhancer. The dry powders, with mannitol as a carrier, were prepared with or without an absorption enhancer (citric acid) by supercritical carbon dioxide (SCF) and spray drying (SD) processes. Insulin powder was precipitated from dimethyl sulfoxide and aqueous solutions by dispersing the insulin solutions from parallel and V-type nozzles, respectively, into supercritical carbon dioxide, which is an antisolvent for insulin. In vitro aerosol performance was evaluated with a cascade impactor. Insulin powder containing citric acid prepared by the SCF method (MIC SCF) showed improved inhalation performance compared with insulin powder prepared by the SD process, although the particle size of the former powder was larger than that in powders prepared by SD. Insulin absorption was estimated from the change in plasma glucose level. The blood glucose level after administration of the insulin powder without citric acid prepared by the SCF process (MI SCF) decreased rapidly, and a significant difference was observed for areas under the curve of change in plasma glucose concentration versus time (AUCs) between MI SCF and the insulin powder without citric acid prepared by the SD process (MI SD). These results suggest that the SCF technique would be useful to prepare dry powders suitable for inhalation.

An attempt was made to produce carrier particles for dry powder inhalations by the surface treatment of lactose particles with aqueous ethanol solution. Drug/carrier powder mixtures were prepared consisting of lactose carriers with different particle surface properties and micronized salbutamol sulfate. These powder mixtures were aerosolized by Spinhaler, and in vitro deposition properties of salbutamol sulfate were evaluated by twin impinger. The degree of adhesion between drug particles and carrier particles was determined by the ultracentrifuge separation method. In addition, the air jet sieve method was used to evaluate characteristics of the separation of drug particles from carrier particles in airflow. The average adhesion force (F50) between the surface-treated lactose carrier and drug particles was significantly lower than that of powder mixed with the untreated lactose carrier, indicating that the degree of separation (T50) of drug particles from carrier particles was improved when surface-treated lactose carrier was used. This resulted in an improvement of in vitro inhalation properties.

Chitosan-plasmid DNA (pDNA) complex powders as a pulmonary gene delivery system were prepared with a supercritical carbon dioxide (CO(2)) process and their in vivo activity was evaluated. The powders with mannitol as a carrier were prepared by dispersing aqueous solutions of a luciferase expression plasmid driven by the cytomegalovirus promoter (pCMV-Luc) with or without chitosan as a cationic vector in a supercritical CO(2)/ethanol admixture. The supercritical CO(2) process with a V-shaped nozzle successfully produced chitosan-pDNA powders. The addition of chitosan suppressed the degradation of pCMV-Luc during the supercritical CO(2) process and increased the yield of powders. The luciferase activity in mouse lung was evaluated after pulmonary administration of the powders or pCMV-Luc solutions. The chitosan-pDNA powders increased the luciferase activity in mouse lung compared with pCMV-Luc powders without chitosan or pCMV-Luc solutions with or without chitosan. The chitosan-pDNA powder with an N/P ratio = 5 increased the luciferase activity to 2700% of that of the pCMV-Luc solution. These results suggest that gene powder with chitosan is a useful pulmonary gene delivery system.