Michael J. Tobyn

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Atomic force microscopy (AFM) was used to investigate drug-carrier interactions between beclometasone dipropionate (BDP) and a series of untreated and modified lactose surfaces. This quantitative information was correlated with bulk characterization methods and an in-vitro study. Modified lactose surfaces were prepared using a proprietary process referred(More)
This study investigates the impact of micronization on the measured surface energy characteristics of an active pharmaceutical ingredient (API), ibipinabant, by inverse gas chromatography (IGC) using both a fixed probe concentration, commonly used in standard IGC methods, and a fixed probe surface coverage approach applied by the surface energy analyzer(More)
Methods are proposed and tested for mimicking the in vitro food effect on controlled release dosage forms, using USP dissolution apparatus 3. Using in vivo data a pH and time profile was constructed, and the methods utilized either presoaking in peanut oil or continuous oil contact to mimic the presence of a high fat meal. A water soluble drug (propranolol(More)
The surface morphology of a-lactose monohydrate particles was modified by a new wet-smoothing process performed in a high-shear mixer using solvents. Successive steps of wetting and drying of lactose powders during rolling in the mixer's cylindrical bowl were performed. Smoothed particles were tested for size distribution, flow, and packing. The(More)
The atomic force microscope (AFM) has been used to characterize the cohesive nature of a micronized pharmaceutical powder used for inhalation therapy. Salbutamol sulfate (also referred to as albuterol sulfate), a therapeutic drug commonly delivered from dry powder inhalers (DPI), was chosen as a model system because the cohesion and subsequent(More)
Surface energy data for samples of microcrystalline cellulose have been obtained using two techniques: capillary intrusion and inverse gas chromatography. Ten microcrystalline cellulose materials, studied using capillary intrusion, showed significant differences in the measured surface energetics (in terms of total surface energy and the acid-base(More)
The role of surface properties, influenced by particle processing, in particle-particle interactions (powder cohesion) is investigated in this study. Wetting behaviour of mefenamic acid was found to be anisotropic by sessile drop contact angle measurements on macroscopic (>1cm) single crystals, with variations in contact angle of water from 56.3° to 92.0°.(More)
This study reports an experimental approach to determine the contribution from two different components of surface energy on cohesion. A method to tailor the surface chemistry of mefenamic acid via silanization is established and the role of surface energy on cohesion is investigated. Silanization was used as a method to functionalize mefenamic acid(More)
The variation of aerosolization with humidity for three micronized drugs used in the treatment of asthma was evaluated by using in vitro methods. Micronized samples of disodium cromoglycate (DSCG), salbutamol sulphate, and triamcinolone acetonide (TAA) were stored for 12hr at 15, 30, 45, 60, and 75% relative humidity (RH). A suitable "reservoir" dry powder(More)