Development of a new disintegration method for orally disintegrating tablets.

Recently, the focus has been on the importance of assessing the oral disintegrative properties of orally disintegrating tablets (ODTs). In particular, in the development stages and the quality control field of ODT products, a physical assessment method which easily measures oral disintegrative properties is desired. For this reason, we developed a new disintegration test method (Kyoto-model disintegration method or KYO method), which is useful to predict the oral disintegrative properties of an ODT easily, and examined the availability of the method. In the KYO method, ODT samples were classified in terms of their water permeability, and a moderate water volume was decided. Subsequently, the disintegrative properties were assessed with the newly proposed method. For 25 commercial prescription ODTs used as samples, a good correlation was shown between the results of a human sensory test by five healthy male volunteers and the results using the KYO method. Furthermore, the KYO method could evaluate time-dependent changes in ODT samples. On the other hand, no correlation was observed between the Japanese Pharmacopeia disintegration test and the human sensory test. These results suggested that the KYO method reflected the disintegration nature of the ODTs in the oral cavity, and could easily be applied to development stages and the quality control field of ODT products.

Determination of indapamide in human serum using 96-well solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS).

A sensitive and specific method using high-performance liquid chromatography (LC)-electrospray tandem mass spectrometry (ESI-MS/MS) for the determination of indapamide in human serum was developed and validated. Indapamide and an internal standard (4-diethylaminobenzoic acid) were isolated from serum samples by solid-phase extraction (SPE) with Oasis HLB 96-well plates and determined by LC-MS/MS in multiple reaction monitoring (MRM) mode. The calibration curve of serum indapamide was linear in the range of 0.2-20 ng/ml with a correlation coefficient of 0.9999. The repeatability, intermediate precisions, and accuracies at 0.2, 5, and 20 ng/ml in serum were less than 15%. The absolute recoveries of indapamide and the internal standard were 79.4-81.5% and 87.5%, respectively, and the low limit of quantitation of serum indapamide was 0.2 ng/mL. The analytical method was applied to a bioequivalence study of KYD-041 (1 mg as film-coated tablets, test formulations) and Natrix Tab.1 (1 mg as sugar-coated tablets, reference formulation). The 90% confidence interval of the ratios (test formulation/reference formulation) for log(Cmax) and log(AUCt) were in the range log(0.80)-log(1.25), which supports the conclusion that KYD-041 is bioequivalent to Natrix Tab.1 with respect to the rate and extent of indapamide absorption.

Application of an electronic nose system for evaluation of unpleasant odor in coated tablets.

The purpose of this study was to apply an electronic nose system for evaluation of unpleasant odor in tablets containing L-cysteine, an unpleasant odor drug, and demonstrate the odor masking ability of thin-layer sugarless coated tablets, which we have newly developed, by both electronic nose system and sensory evaluations. We demonstrated the qualitative evaluation of the unpleasant odor using air as a reference indicator and the quantitative evaluation of the unpleasant odor using the distances between air and samples in the electronic nose system evaluation. The electronic nose system evaluation was positively and well-correlated with the sensory evaluation by volunteers. We suggest that the electronic nose system evaluation is appropriate as an alternative or a support method for sensory evaluation by volunteers. As the results of both electronic nose system and sensory evaluations, we demonstrated that the thin-layer sugarless coated tablets have excellent masking ability of the unpleasant odor, equivalent to that of sugar-coated tablets due to the dense coating layers.

Monitoring of the tissue distribution of fibroblast growth factor containing a high mannose-type sugar chain produced in mutant yeast.

Most therapeutic glycoproteins have been produced in mammalian cell lines. However, the mammalian cell culture system has various disadvantages, i.e., a high culture cost, difficulty in performing a large scale-up because of complicated handling requirements, and the risk of contamination by prion or other unknown pathogenic components through cultivation in the presence of bovine serum. There is thus a growing need for other host cells in which the recombinant glycoproteins can be produced. Recently, we successfully developed a mutant yeast strain engineered in a glycosylation system. The sugar chain produced in the mutant yeast is not immunogenic to the human immuno-surveillance system. In the present study, we selected fibroblast growth factor (FGF) as a model glycoprotein and assessed the bioactivity of FGF produced in yeast in terms of its proliferating activity and tissue distribution in mammalian cells and in the whole body. Structural changes in the sugar chains of FGFs derived from mutant yeast, as compared with those from mammalian cells, did not affect the proliferating activity remarkably. However, the tissue distribution in the mouse differed significantly; a high-mannose type sugar chain was the major determinant of the specific distribution of FGF to the kidney. The mechanism of this phenomenon is still unclear, but our observations suggest that recombinant glycoproteins derived from mutant yeasts producing high-mannose type sugar chains would be applicable for tissue-targeting therapy.

Characteristics of erythritol and formulation of a novel coating with erythritol termed thin-layer sugarless coating.

The purpose of this study was to clarify the characteristics of erythritol and to develop the optimum basic formulation of a novel coating with erythritol termed thin-layer sugarless coating. Characteristics of erythritol were investigated compared with maltitol, mannitol, sorbitol, xylitol, and sucrose. Furthermore, the optimum basic formulation of thin-layer sugarless coating with erythritol was determined by coating glass beads. We selected a continuous spray mist method for thin-layer sugarless coating due to the formation of a thin sugarless coating layer by a simple method. We demonstrated that erythritol is a suitable coating material for thin-layer sugarless coating compared with maltitol, mannitol, sorbitol, xylitol, and sucrose because of its high water solubility, low hygroscopicity, instant crystallization, and low tackiness. We also demonstrated that thin-layer sugarless coating with erythritol can reduce coating time compared with the coating with maltitol or sucrose due to its characteristics. We developed the optimum basic formulation of thin-layer sugarless coating consists of erythritol, powdered acacia, and talc. We confirmed that a smooth coating layer and high coating efficiency were achieved using the formulation.

Development and evaluation of the tablets coated with the novel formulation termed thin-layer sugarless coated tablets.

The purpose of this study was to develop and evaluate the thin-layer sugarless coated tablets containing Vitamin C, Vitamin E, Vitamin B2, calcium pantothenate, and L-cysteine. As a result of the formulation study, three coating layers, 2% under coating (UC), 38% build-up coating (BC), and 5% syrup coating (SC) were necessary for sufficient impact toughness, elegant appearance, and improvement of appearance stability after storage at 25 degrees C/75% RH for 6 months under open conditions. We demonstrated that the thin-layer sugarless coated tablets are superior to the sugar-coated tablets in terms of small tablet size and stability of calcium pantothenate. It was due to the coating method, the continuous spray mist method, which can minimize the thicknesses of coating layers and the moisture content in the tablets. We also demonstrated that the thin-layer sugarless coated tablets are superior to the film-coated tablets in terms of masking ability of the unpleasant odor and the appearance, stability of the appearance, and low hygroscopicity. It was due to the dense, opaque, and stable coating layers mainly consist of erythritol. We revealed that thin-layer sugarless coated tablets have both advantages of film-coated tablets and sugar-coated tablets.

Improvement of impact toughness of sugar-coated tablets manufactured by the dusting method.

The purpose of this study was to improve the impact toughness of sugar-coated tablets manufactured by a dusting method. The effects of sugar-coating formulations, which were the sugar-coating suspension formulations and the dusting powder formulations, on impact toughness of sugar-coated tablets were investigated. Impact toughness of sugar-coated tablets was measured by the friability test. We found that the dusting powder formulation was a control factor in impact toughness of sugar-coated tablets manufactured by the dusting method. The dusting method using dusting powder containing 20% microcrystalline cellulose (MCC, Avicel PH-F20) was a useful method for improvement of the impact toughness of sugar-coated tablets. The mechanism of improvement of impact toughness was that MCC in the subcoating layer resulted in a tight bond between the subcoating layer and the smoothing layer and prevented separation of the two layers on impact, because MCC improved the wettability of the subcoating layer, increased the surface roughness of the subcoating layer, and played the role of a binder between the two layers. We confirmed that the MCC between the subcoating layer and the smoothing layer acts to prevent separation of the two layers by impact. We demonstrated that MCC is a suitable material for sugar-coating in order to improve the impact toughness of sugar-coated tablets.

Effect of moisture on impact toughness of sugar-coated tablets manufactured by the dusting method.

The purpose of this study was to clarify the effect of moisture on the impact toughness of sugar-coated tablets manufactured by the dusting method. We demonstrated that moisture plays an important role in the impact toughness of sugar-coated tablets. Moisturizing the sugar-coating layer resulted in enhancement of impact toughness of sugar-coated tablets, while reducing moisture in the sugar-coating layer resulted in weakening of the impact toughness. This was due to the characteristics of sucrose, the main ingredient of the sugar-coating layer, which is a soft and non-fragile material at high moisture levels, but hard and fragile at low moisture levels. We also demonstrated that friability as an indicator of impact toughness changed with time, and friability should be measured at 14 d after manufacture. This is due to moisture movement from outer sugar-coating layer into the inner sugar-coated tablets. Incorporating microcrystalline cellulose (MCC) in the subcoating layer resulted in sugar-coating layers with high resistance against impact even though moisture content of sugar-coated tablets was low. We confirmed the high impact toughness of the sugar-coated tablets with MCC whose moisture content was low from the results of both free fall and friability tests. We suggest that the dusting method using dusting powder containing MCC is a useful method for the production of sugar-coated tablets containing moisture sensitive drugs.

Monitoring biodistribution of glycoproteins with modified sugar chains.

Natural human interferon (hIFN)-gamma has mainly biantennary complex-type sugar chains. Previously, we successfully remodeled its sugar chain structure into: (a) highly branched types; or (b) highly sialylated types, by overexpression of: (a) N-acetylglucosaminyltransferase (GnT)-IV and/or GnT-V; or (b) sialyltransferases, in Chinese hamster ovary (CHO) cells. In addition, we prepared asialo hIFN-gammas by treatment with sialidase in vitro. In the present study, we assessed the bioactivity of remodeled hIFN-gamma in terms of antiviral activity, anticellular activity, and biodistribution. Structural changes to the sugar chains did not have a significant influence on the antiviral and anticellular activities of hIFN-gamma, although the attachment of the sugar chain itself affected both activities. However, the biodistribution differed significantly; the number of exposed galactose residues was the major determinant of the specific distribution to the liver and blood clearance rate of hIFN-gamma. This phenomenon was considered to be mediated by the hepatic asialoglycoprotein receptor (ASGP-R), and we showed a linear, not exponential, enhancement of the distribution to the liver with an increase in the number of exposed galactose residues. We also confirmed this tendency using fibroblast growth factor (FGF). Our observation is not the same as the "glycoside cluster effect." We thus provide important information on the character of modified recombinant glycoproteins.