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Bruno C Hancock

Publications and source records attributed to Bruno C Hancock.

4 recordsLinked to original sources
PubMed2003

The powder flow and compact mechanical properties of sucrose and three high-intensity sweeteners used in chewable tablets.

The physical, flow, and mechanical properties of four common pharmaceutical sweeteners were measured to assess their relative manufacturability in solid dosage formulations. Sucrose, acesulfame potassium (Sunett), saccharin sodium, and aspartame were evaluated to determine significant differences in particle shape, size distribution, and true density. Powder flow and cohesivity as well as compact mechanical properties such as ductility, elasticity, and tensile strength were measured and found to be noticeably different. Among these sweeteners, sucrose and acesulfame potassium demonstrated excellent flowability and marginal mechanical property performance relative to over 100 commonly used pharmaceutical excipients evaluated in the authors' laboratory. Saccharin sodium and aspartame demonstrated poor flowability and superior compact strength relative to sucrose and acesulfame, despite their noticeably higher brittleness. These data suggest that careful selection of an appropriate sweetener is warranted in obtaining desirable process and tableting robustness, particularly if sweetener loading is high. Detailed descriptions of each material property and recommendations for sweetener selection in formulation development are included.

Elasticity↗
PubMed2002

Comparison of the mechanical properties of the crystalline and amorphous forms of a drug substance.

PURPOSE: To better understand the influence of long-range molecular order on the processing characteristics of an active pharmaceutical ingredient (API). METHODS: Crystalline and amorphous samples of a model drug substance were isolated and their "true" density, crystallinity, melting point, glass transition temperature, particle size distribution, and powder flow characteristics determined. Compacts of a standard porosity were manufactured from each form and their dynamic indentation hardness, quasi-static indentation hardness, tensile strength and "compromised tensile strength" determined. X-ray powder diffraction was used to confirm that no changes were induced by compact formation or testing. RESULTS: The crystalline and amorphous forms of the drug substance had relatively high melting and glass transition temperatures (approximately 271 and 142 degrees C, respectively) and were physically and chemically stable under the conditions of the testing laboratory. Consistent with this there was no evidence of crystallinity in the amorphous samples or vice versa before, during or after testing. The two API lots were effectively equivalent in their particulate properties (e.g. particle size distribution), although differences in their particle morphologies were observed which influenced powder flow behavior. The compacts of the bulk drug samples exhibited moderate ductility, elasticity, and strength, and high brittleness, in keeping with many other drug substance samples. A significantly greater compression stress was required to form the compacts of the crystalline material, and these sample materials were more ductile, less brittle and less elastic than those made from the amorphous API. There were no major differences in the tensile strength or the viscoelasticity of the compacts made from the crystalline and amorphous samples. CONCLUSIONS: The mechanical properties of compacted amorphous and crystalline samples of a drug substance have been measured and the contributions due to the molecular ordering of the crystalline form proposed. Small but significant differences in the mechanical properties were noted which could potentially affect the processing performance of API.

Chemical Phenomena↗
PubMed2002

Disordered drug delivery: destiny, dynamics and the Deborah number.

"Disordered drug delivery" is an innovative approach to improving the performance of new chemical entities delivered to the human body. In this technique, the molecules of the drug and/or its delivery system are kinetically trapped in a high energy non-crystalline state. The resulting disordered or "amorphous" material offers potential increases in solubility and biological activity of many thousand fold compared with more conventional crystalline forms of the drug. Despite having a molecular level structure akin to that of liquids, amorphous materials have macroscopic properties that are typical of solids and thus they may be presented to the patient in the form of a convenient solid dosage form. Significant advances in the fundamental understanding of amorphous pharmaceutical materials in the past ten years have permitted major steps forward in the rational design of disordered drug delivery systems. Recognition of significant levels of molecular mobility in the glassy regime and an in-depth appreciation of molecular relaxation times and their distributions have enabled rapid progress to be made in this field. Needs for the future include analytical techniques that can elucidate the complex, dynamic and heterogeneous structure of amorphous materials and reliable models to predict the physical stability and in-vivo performance of disordered drug delivery systems. There are also significant opportunities for the production of disordered drug delivery systems with tailor-made properties through the careful engineering of custom amorphous alloys.

Chemical Phenomena↗