Publications by authors named "D CoffinBeach"

Frequency-domain photon migration (FDPM) measurements of time-dependent light propagation are conducted to provide the powder absorbance for quantitative prediction of terazosin as the active pharmaceutical ingredient (API) in a low-dose (0.72 wt %) oral tablet formulation. Calibration of the FDPM-derived powder absorbance at discrete wavelengths of 514, 650, 687, and 785 nm was performed for API contents ranging between 0 and 1.

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The roles of blender rotational speed and blender discharge on the homogeneity of free-flowing art sand and of a cohesive placebo formulation were investigated in the tote blender. For three practical operating speeds, 6, 10, and 14 RPM, spanning the entire range of commercial equipment, the homogeneity of the free-flowing mixture was independent of rotational speed and blender size. On the other hand, the homogeneity of the cohesive pharmaceutical powder mixture was dependent on vessel rotational speed in a complex fashion, with 10 RPM producing a better final mixture than either 5 or 15 RPM.

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Experiments were conducted to determine the influence of process parameters such as fill level, mixing time, shear, and baffle presence along with material attributes such as initial active aggregate size and concentration on the homogeneity of a cohesive placebo formulation in a pilot plant scale tote blender. The formulation was a ternary system made up of microcrystalline cellulose, NaCl or KCl salt, and magnesium stearate. Blend homogeneity was evaluated by sampling the blend using core samplers.

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An NMR imaging method was developed to estimate the rate of water movement in slow-release capsule matrices of pseudoephdrine HCl and hydroxypropyl cellulose (HPC). Test capsules were first placed in a USP method 2 (paddles, 50 rpm) dissolution apparatus. Each plug was removed from the dissolution medium at predetermined times, blotted dry, and placed within the magnetic field of a General Electric 400-MHz wide-bore NMR spectrometer equipped with a microimaging accessory.

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Crystalline polyvinyl alcohol (PVA) polymer and low-crystallinity polyvinyl alcohol-methyl acrylate copolymer (PVA-MA) were examined as sustained-release tablet excipients with theophylline as a model drug. By blending of different proportions of the crystalline polymer and the low-crystallinity copolymer, it was possible to affect the release characteristics of the tablets. Tablets made with crystalline PVA provided instant release of theophylline in vitro.

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