scispace - formally typeset
Search or ask a question
Author

Toshio Oguchi

Other affiliations: Chiba University
Bio: Toshio Oguchi is an academic researcher from University of Yamanashi. The author has contributed to research in topics: Differential scanning calorimetry & Solubility. The author has an hindex of 25, co-authored 111 publications receiving 1911 citations. Previous affiliations of Toshio Oguchi include Chiba University.


Papers
More filters
Journal ArticleDOI
TL;DR: The results demonstrated that acid value (AV) of shellac increased with prolongation of hydrolysis time, and the films prepared from hydrolysed shellac were more flexible and soft than those prepared from native shellac.

115 citations

Journal ArticleDOI
TL;DR: In order to characterize the amorphous clarithromycin (CAM) obtained by grinding and spray drying, physicochemical properties were evaluated and the increase of the special term, deltas, indicated that the energy change was due to the polarity of the surface energy of the powder particles by grinding.

108 citations

Journal ArticleDOI
TL;DR: In this article, the dissolution rate of ofloxacin was markedly increased in solid dispersion of urea and mannitol, and the results from differential scanning calorimetry (DSC), powder x-ray diffraction (PXRD) analysis and infrared spectroscopy (IR) were performed to evaluate the physicochemical properties of the prepared solid dispersions.

104 citations

Journal ArticleDOI
K Itoh1, Adchara Pongpeerapat1, Yuichi Tozuka1, Toshio Oguchi1, Keiji Yamamoto1 
TL;DR: Poorly water-soluble drugs N-5159, griseofulvin (GFV), glibenclamide (GBM) and nifedipine (NFP) were ground in a dry process with polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS).
Abstract: Poorly water-soluble drugs N-5159, griseofulvin (GFV), glibenclamide (GBM) and nifedipine (NFP) were ground in a dry process with polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS). Different crystallinity behavior of each drug during grinding was shown in the ternary Drug/PVP/SDS system. However, when each ternary Drug/PVP/SDS ground mixture was added to distilled water, crystalline nanoparticles which were 200 nm or less in size were formed and had excellent stability. Zeta potential measurement suggested that the nanoparticles had a structure where SDS was adsorbed onto the particles that were formed by the adsorption of PVP on the surface of drug crystals. Stable existence of crystalline nanoparticles was attributable to the inhibition of aggregation caused by the adsorption of PVP and SDS on the surface of drug crystals. Furthermore, the electrostatic repulsion due to the negative charge of SDS on a shell of nanoparticles could be assumed to contribute to the stable dispersion.

76 citations

Journal ArticleDOI
TL;DR: The optimization of oral dosage form formulation has been developed for N-4472, N-[2-(3,5-di-tert-butyl-4-hydroxyphenethyl)-4,6-difluorophenyl]-N'-[4-(N-benzylpiperidyl)] urea, which was a poorly water-soluble drug having a lipid-lowering effect.

72 citations


Cited by
More filters
Journal ArticleDOI
10 Mar 1970

8,159 citations

Journal ArticleDOI
TL;DR: The historical background and definitions of the various systems including eutectic mixtures, solid dispersions and solid solutions, as well as the production, the different carriers and the methods used for the characterization of solid dispersion are outlined.

2,695 citations

Journal ArticleDOI
TL;DR: Amorphous pharmaceuticals are markedly more soluble than their crystalline counterparts, however, their experimental solubility advantage is typically less than that predicted from simplethermodynamic considerations.
Abstract: Purpose To evaluate the magnitude of the solubility advantage foramorphous pharmaceutical materials when compared to their crystallinecounterpartsMethods The thermal properties of several drugs in their amorphousand crystalline states were determined using differential scanningcalorimetry From these properties the solubility advantage for theamorphous form was predicted as a function of temperature using a simplethermodynamic analysis These predictions were compared to theresults of experimental measurements of the aqueous solubilities of theamorphous and crystalline forms of the drugs at several temperaturesResults By treating each amorphous drug as either an equilibriumsupercooled liquid or a pseudo-equilibrium glass, the solubilityadvantage compared to the most stable crystalline form was predicted to bebetween 10 and 1600 fold The measured solubility advantage wasusually considerably less than this, and for one compound studied indetail its temperature dependence was also less than predicted It wascalculated that even for partially amorphous materials the apparentsolubility enhancement (theoretical or measured) is likely to influencein-vitro and in-vivo dissolution behaviorConclusions Amorphous pharmaceuticals are markedly more solublethan their crystalline counterparts, however, their experimental solubility advantage is typically less than that predicted from simplethermodynamic considerations This appears to be the result of difficulties indetermining the solubility of amorphous materials under trueequilibrium conditions Simple thermodynamic predictions can provide a useful indication of the theoretical maximum solubility advantage foramorphous pharmaceuticals, which directly reflects the driving forcefor their initial dissolution

1,322 citations

Journal ArticleDOI
TL;DR: The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology where required.
Abstract: Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

1,201 citations

Journal ArticleDOI
TL;DR: In this article, the authors reviewed several novel examples of pharmaceutical cocrystals from the past decade and analyzed the enhanced solubility profiles of cocrystal profiles, showing that the peak dissolution for pharmaceutical cocystals occurs in a short time (<30 min), and high-solubility is maintained over a sufficiently long period (4-6 h) for the best cases.
Abstract: The current phase of drug development is witnessing an oncoming crisis due to the combined effects of increasing R&D costs, decreasing number of new drug molecules being launched, several blockbuster drugs falling off the patent cliff, and a high proportion of advanced drug candidates exhibiting poor aqueous solubility. The traditional approach of salt formulation to improve drug solubility is unsuccessful with molecules that lack ionizable functional groups, have sensitive moieties that are prone to decomposition/racemization, and/or are not sufficiently acidic/basic to enable salt formation. Several novel examples of pharmaceutical cocrystals from the past decade are reviewed, and the enhanced solubility profiles of cocrystals are analyzed. The peak dissolution for pharmaceutical cocrystals occurs in a short time (<30 min), and high solubility is maintained over a sufficiently long period (4–6 h) for the best cases. The enhanced solubility of drug cocrystals is similar to the supersaturation phenomenon ...

818 citations