Takehisa Nakajima

Preparation and properties of inhalable nanocomposite particles for treatment of lung cancer.

Nanoparticles have widely been studied in drug delivery research for targeting and controlled release. The aim of this article is application of nanoparticles as an inhalable agent for treatment of lung cancer. To deposit effectively deep the particles in the lungs, the PLGA nanoparticles loaded with the anticancer drug 6-{[2-(dimethylamino)ethyl]amino}-3-hydroxyl-7H-indeno[2,1-c]quinolin-7-one dihydrochloride (TAS-103) were prepared in the form of nanocomposite particles. The nanocomposite particles consist of the complex of drug-loaded nanoparticles and excipients. In this study, the anticancer effects of the nanocomposite particles against the lung cancer cell line A549. Also, the concentration of TAS-103 in blood and lungs were determined after administration of the nanocomposite particles by inhalation to rats. TAS-103-loaded PLGA nanoparticles were prepared with 5% and 10% of loading ratio by spray drying method with trehalose as an excipient. The 5% drug-loaded nanocomposite particles were more suitable for inhalable agent because of the sustained release of TAS-103 and higher FPF value. Cytotoxicity of nanocomposite particles against A549 cells was higher than that of free drug. When the nanocomposite particles were administered in rats by inhalation, drug concentration in lung was much higher than that in plasma. Furthermore, drug concentration in lungs administered by inhalation of nanocomposite particles was much higher than that after intravenous administration of free drug. From these results, the nanocomposite particle systems could be promising for treatment of lung cancer.

Preparation and properties of inhalable nanocomposite particles: Effects of the size, weight ratio of the primary nanoparticles in nanocomposite particles and temperature at a spray-dryer inlet upon properties of nanocomposite particles

Nanoparticles are expected to be applicable to inhalation as carrier but there exist disadvantages because of their size. Their deposition dose to the lung will be small. To overcome this problem and utilize nanoparticles for inhalation, we have prepared nanocomposite particles as drug carriers targeting lungs. The nanocomposite particles are prepared as drug-loaded nanoparticles-additive complex to reach deep in the lungs and to be decomposed into nanoparticles when they deposit into lung. In this study, we examined the effect of preparation condition--inlet temperature, size of primary nanoparticles and weight ratio of primary nanoparticles--on the property of nanocomposite particles. When the size of primary nanoparticles was 400 nm and inlet temperature was 90 degrees C, only the nanocomposite particles containing between 45 and 55% of primary nanoparticles could be decomposed into nanoparticles in water. On the other hand, when the inlet temperature was 80 degrees C, nanocomposite particles were decomposed into nanoparticles independent of the weight ratio of primary nanoparticles. Also, the aerodynamic diameter of the nanocomposite particles was between 1.5 and 2.5 microm, independent of the weight ratio of primary nanoparticles. When the size of primary nanoparticles was 200 nm and inlet temperature was 70 degrees C, nanocomposite particles were decomposed into nanoparticles independent of the weight ratio of primary nanoparticles. Also, the aerodynamic diameters of them were almost 2.0 microm independent of the weight ratio of primary nanoparticles. When the nanocomposite particles containing nanoparticles with the size of 200 nm are prepared at 80 degrees C, no decomposition into nanoparticles was observed in water. Fine particle values, FPF, of the nanocomposite particles were not affected by the weight ratio of primary nanoparticles when they were prepared at optimum inlet temperature.

Pulsatile drug release from poly (lactide-co-glycolide) microspheres: how does the composition of the polymer matrices affect the time interval between the initial burst and the pulsatile release of drugs?

Abstract Pulsatile release of estradiol was observed from poly (lactide-co-glycolide) microspheres, of which the monomer composition was 75% lactide and 25% glycolide. Estradiol was monolithically dissolved in the polymer matrices. The microspheres were immersed in a pH 7.4 phosphate buffer saline at 37°C. When estradiol was loaded in microspheres consisting of poly (lactide-co-glycolide) of average molecular weight ( M w ) of 74 000 before degradation, the pulse of estradiol release was observed almost 50 days after the initial burst. On the other hand, if poly (lactide-co-glycolide) of M w 44 000 before degradation was used as a material to prepare the microspheres, then estradiol was released in a pulsatile manner almost 20 days after the initial burst effect. It was found that the time interval between the initial burst and the pulsatile release can be regulated by mixing the above two types of poly (lactide-co-glycolide) with different M w to prepare microspheres. For example, the pulsatile release of estradiol was observed 30 days after the degradation starts when the microspheres were composed of 50% poly (lactide-co-glycolide) of M w 74 000 and 50% poly (lactide-co-glycolide) of M w 44 000. In another case where the microspheres were composed of 75% poly (lactide-co-glycolide) of M w 74 000 and 25% poly (lactide-co-glycolide) of M w 44 000, the pulsatile release was observed 38 days after the degradation starts.

Sustained release of 17β-estradiol from poly (lactide-co-glycolide) microspheres in vitro and in vivo

Poly (lactide-co-glycolide) microspheres containing four different concentrations (0.15, 0.3, 1.5, 2.25% (w/w)) of 17β-estradiol, all of which are monolithic devices, were prepared by a solvent evaporation method. In the preparation process, poly (lactide-co-glycolide) was dissolved in dichloromethane and estradiol was then dissolved or partly dispersed in the solution. The polymer solution containing drugs was emulsified in water to prepare o/w emulsion. Effects of surfactants and aqueous polymers added to the outer aqueous phase upon the emulsion stability were studied. It was found that polyvinylalcohol effectively stabilizes the dichloromethane in water emulsion. Effects of the estradiol concentration in the microspheres upon its release rate were studied. When the estradiol concentration in the microsphere is less than 0.3% (w/w), estradiol molecules can be dissolved in polymer matrices. When the estradiol concentrations in the microspheres are 1.5 and 2.25% (w/w), however, estradiol crystals exist in a microsphere as a dispersion in the polymer matrices together with estradiol molecules dissolved in the matrices. Sustained release of estradiol from poly (lactide-co-glycolide) microspheres containing 0.15 and 0.3% (w/w) was observed for 30 days in both systems, while that from poly (lactide-co-glycolide) microspheres containing 1.5 and 2.25% (w/w) was observed for 100 days in both systems. It was found that the release of estradiol from poly (lactide-co-glycolide) microspheres is affected by the following three mechanisms: (i) the release of estradiol molecules accompanied with the removal of degraded short polymer chains; (ii) the dissolution of estradiol crystals into polymer matrices and aqueous solution and (iii) pore formation in polymer matrices caused by the polymer degradation. In vivo study, estradiol was released with a constant rate from poly (lactide-co-glycolide) microspheres containing 0.3% estradiol and the plasma concentration of estradiol was kept constant at 1.5 ng ml−1 for 50 days.

Preparation and properties of carrageenan microspheres containing allopurinol and local anesthetic agents for the treatment of oral mucositis

For the treatment of oral mucositis, carrageenan microspheres containing allopurinol and local anesthetic agents, such as lidocaine hydrochloride, dibucaine hydrochloride and tetracaine hydrochloride were prepared using a spray-drying method. As base materials, kappa-carrageenan and iota-carrageenan were evaluated, since carrageenan mitigates bitter taste of lidocaine hydrochloride, dibucaine hydrochloride and tetracaine hydrochloride. The microspheres were spherical and their average diameters were about 10 microm. The drug loading efficiency was more than 70%. Allopurinol and local anesthetic agents became amorphous by the spray drying. Allopurinol and the local anesthetic agents were released from the microspheres for at least 400 min when iota-carrageenan was used as a base material. On the other hand, the release was prolonged to 600 min when kappa-carrageenan was used. The microspheres were spread and made membranes at the air/water interfaces immediately after dropped on the water surfaces. The properties of the microspheres such as dispersing efficacy and membrane production on the water surfaces suggest that the microspheres can uniformly cover inner surfaces of oral cavity to prevent and treat oral mucositis.

Exact determination of phagocytic activity of alveolar macrophages toward polymer microspheres by elimination of those attached to the macrophage membrane

A method for exact determination of phagocytic activity of alveolar macrophage (Mvarphi) cells toward synthetic microspheres (MS) by optical microscopy was developed. We examined the effectiveness of the treatment of Mvarphi samples with trypsin, acid or xylene to remove the polystyrene latex microspheres (PSL MS) attached to Mvarphi cell membranes during their phagocytosis by Mvarphi cells. We found that centrifugation, which was employed to collect Mvarphi samples after incubation with MS, affected significantly the efficiency of the various treatments. Of the three treatments, xylene treatment without centrifugation was the most effective to determine the phagocytic activity of Mvarphi cells, as xylene dissolved the PSL MS on the cell surface almost completely. This treatment was also effective in the case of poly(lactic-co-glycolic acid) MS (PLGA MS), which have been commonly used as an efficient vehicle for drug delivery system.

Estimation of crystallinity of trehalose dihydrate microspheres by usage of terahertz time‐domain spectroscopy

Crystalline state of pharmaceutical materials is of great importance in the preparation of pharmaceutics because their physicochemical properties affect bioavailability, quality of products, therapeutic level, and manufacturing process. In this study, we have estimated the crystallinity of trehalose dihydrate microspheres by measuring terahertz (THz) spectroscopy. The commercially available trehalose dihydrate takes in general a crystalline state, but trehalose dihydrate microspheres prepared by using spray-drying method are in an amorphous state. We have prepared amorphous anhydrous trehalose by using melt-quenched method from crystalline trehalose dihydrate. We have measured the absorbance of trehalose dihydrate containing amorphous anhydrous trehalose (0%, 25%, 50%, 75%, and 100%) using THz time-domain spectroscopy (THz-TDS) to prepare calibration curves. Using the calibration curves, we have estimated the crystallinity of trehalose dihydrate microspheres prepared by using spray-drying method. Our results suggest that THz-TDS is well suited to distinguish crystallinity differences in pharmaceutical compounds.

Distribution and deposition of respirable PLGA microspheres in lung alveoli.

Although treatment of pulmonary tuberculosis with respirable microspheres (MS) with an incorporated antituberculosis drug is expected to be highly effective, this treatment seems to achieve a much lesser effect than expected in the case of killing Mycobacterium tuberculosis residing in the lungs. To elucidate the reason for this weaker effect, we examined the distribution and accumulation of respirable MS consisting of poly(lactic-co-glycolic) acid (PLGA) in rat lungs. For this, we delivered the PLGA MS containing fluorescent coumarin 6 or an antituberculosis agent, rifampicin (RFP), by insufflation via the trachea and then determined the pulmonary distribution by counting the number of the MS in lung cryosections observed under a microscope. In addition, the uptake of MS by alveolar macrophage (AMφ) was determined by immunostaining for Mφ cell marker CD68 and RFP content in the cells. Approximately half of the fluorescent PLGA MS reached the alveoli without entrapment by trachea and primary bronchi and were then ingested by the AMφ cells up to 24h after insufflation. RFP in a form of PLGA MS was markedly transported into AMφ at an amount 10 times greater than that for the free RFP powder. However, a large proportion of RFP was eliminated from the lungs by 6h after insufflation.

Phagostimulatory effect of uptake of PLGA microspheres loaded with rifampicin on alveolar macrophages

Our previous results on the phagocytic activity of alveolar macrophages (Mϕs) toward poly(lactic-co-glycolic) acid microspheres (PLGA MS) loaded with the anti-tuberculosis agent rifampicin (R-PLGA MS) suggest that the phagocytosis of R-PLGA MS enhances the phagocytic activity of Mϕ cells. To confirm this possibility, we examined the effect of phagocytosis of R-PLGA MS and polystyrene latex (PSL) MS on the phagocytic uptake of fluorescent PSL (F-PSL) MS by cells of the rat alveolar macrophage cell line NR8383 at 37°C. Phagocytic activity was examined in terms of the population of Mϕ cells that had phagocytosed MS (N(total)) and the total number of MS phagocytosed (n(total)) by counting the phagocytic Mϕ cells and the MS ingested in optical microscopic fields. Phagocytosis of R-PLGA MS enhanced about 1.5 times the values of N(total) and n(total) of the phagocytosis of F-PSL MS under the conditions where the phagocytosis of F-PSL MS did not attain the saturated level. In contrast, the phagocytosis of PSL MS did not enhance the phagocytic activity of Mϕ cells toward F-PSL MS. In conclusion, R-PLGA MS are favorable for drug delivery of anti-tuberculosis agents into alveolar Mϕs due to their ability to up-regulate the phagocytosis of MS.

Nondestructive Analysis of Structure and Components of Tablet Coated with Film by the Usage of Terahertz Time-Domain Reflection Spectroscopy

Nondestructive analysis of tablet is of great importance from the aspect of productivity and safety. In terahertz (THz) region, however, the analysis of core of coated tablet has not been progressed. In this study, we have measured a flat-surface push-pull osmotic pump tablet, having no orifice, having bilayer core and a coating film layer. The bilayer core was made from the drug layer and the push layer, and acetaminophen was contained in the drug layer as a model drug. To study its structure and components, we have obtained reflection spectra from the drug layer side and the push layer side measurements using THz time-domain reflection spectroscopy (THz-TDRS). From these results, detection of the peak of acetaminophen in the spectrum from the drug layer side measurements was confirmed. We have made ridges approximated toward the peak using a general method of linear regression analysis in both spectra. Two-sample t-test was applied to their gradients, and significant difference between the drug layer and the push layer was shown. These results suggested that THz-TDRS is applicable to the analysis of structure and component of a coated tablet.