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Willis R. Whitney

Bio: Willis R. Whitney is an academic researcher. The author has contributed to research in topics: Solid substance & Dissolution. The author has an hindex of 1, co-authored 1 publications receiving 1485 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the effect of the concentration on the rate at which a solid substance dissolves in its own solution, has not heretofore been investigated, probably due to the experimental difficulties in the way of keeping the surface of the dissolving substance constant during the solution.
Abstract: As far as we know, the effect of the concentration on the rate at which a solid substance dissolves in its own solution, has not heretofore been investigated. This is probably due to the experimental difficulties in the way of keeping the surface of the dissolving substance constant during the solution.

1,653 citations


Cited by
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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
Abu T.M. Serajuddin1
TL;DR: Physicochemical principles of salt solubility are presented, with special reference to the influence of pH-solubility profiles of acidic and basic drugs on salt formation and dissolution.

1,286 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: The aims of this article are to clarify under which circumstances dissolution testing can be prognostic for in vivo performance, and to present physiological data relevant to the design of dissolution tests, particularly with respect to the composition, volume, flow rates and mixing patterns of the fluids in the gastrointestinal tract.
Abstract: Dissolution tests are used for many purposes in the pharmaceutical industry: in the development of new products, for quality control and, to assist with the determination of bioequivalence. Recent regulatory developments such as the Biopharmaceutics Classification Scheme have highlighted the importance of dissolution in the regulation of post-approval changes and introduced the possibility of substituting dissolution tests for clinical studies in some cases. Therefore, there is a need to develop dissolution tests that better predict the in vivo performance of drug products. This could be achieved if the conditions in the gastrointestinal tract were successfully reconstructed in vitro. The aims of this article are, first, to clarify under which circumstances dissolution testing can be prognostic for in vivo performance, and second, to present physiological data relevant to the design of dissolution tests, particularly with respect to the composition, volume, flow rates and mixing patterns of the fluids in the gastrointestinal tract. Finally, brief comments are made in regard to the composition of in vitro dissolution media as well as the hydrodynamics and duration of the test.

1,080 citations

Journal ArticleDOI
TL;DR: The principles behind nanosizing, the production and characterization of nanoformulations as well as the current experience with utilization of such formulations in vivo are described.

967 citations