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Papers by Owen I Corrigan

Research paper thumbnail of In vitro analysis of the release of incorporated agents from sodium caseinate microspheres

Journal of Microencapsulation, 1997

Drug loaded microspheres were successfully prepared using the dairy protein, sodium caseinate (SC... more Drug loaded microspheres were successfully prepared using the dairy protein, sodium caseinate (SC), as the carrier material and containing hydrochlorothiazide, eosin, patent blue violet and sodium salicylate. The morphology of the microspheres varied depending on the incorporated material. Release of the incorporated agents from these systems was rapid with over 90% release in each case within 1 h. Further drug release occurred at a greatly reduced rate with a certain proportion of the drug loading appearing to be indefinitely entrapped within some of the microspheres. The drug release profiles were poorly described using the square root of time and Sinclair and Peppas equations but were well described by a biexponential equation. Analysis of the parameter estimates from the biexponential equation indicated that the initial rapid release phase was essentially completed within 5 min for all but the eosin microsphere systems and this timeframe was of the same order of magnitude as that found for the initial swelling of these microsphere systems as analysed by swelling studies using optical microscopy. Considering both the swelling study and the results from the release experiments, it seems likely that addition of SC microspheres to aqueous media results in immediate hydration and swelling. This process facilitates the rapid diffusional passage of water soluble drugs through the swollen and hydrated microsphere matrix, with drug release occurring almost unhindered unless other factors favour the retention of the incorporated agent with the microsphere.

Research paper thumbnail of Comparison of the physicochemical properties of the N-(2-hydroxyethyl) pyrrolidine, diethylamine and sodium salt forms of diclofenac

International Journal of Pharmaceutics, Jul 1, 2001

ABSTRACT

Research paper thumbnail of Temperature dependence and thermodynamics of partitioning of clofazimine analogues in the n-octanol/water system

International Journal of Pharmaceutics, 1990

International Journal of Pharmaceutics, 58 (1990) 107-113 Elsevier UP 01962 107 Temperature depen... more International Journal of Pharmaceutics, 58 (1990) 107-113 Elsevier UP 01962 107 Temperature dependence and thermodynamics of partitioning of clofazimine analogues in the ^-octanol/water system John M. Quigley Khairi MS Fahelelbom Richard F. Timoney 1 and Owen I. ...

Research paper thumbnail of Particle engineering of materials for oral inhalation by dry powder inhalers. I—Particles of sugar excipients (trehalose and raffinose) for protein delivery

International Journal of Pharmaceutics, Feb 28, 2011

Research paper thumbnail of Erratum to: In vitro evaluation physiological availability of aspirin tablets

Irish Journal of Medical Science, May 1, 1970

Research paper thumbnail of A study of community pharmacy practice, 2: Prescription Dispensing

An observational study of prescription dispensing in 40 community pharmacies in Dublin found that... more An observational study of prescription dispensing in 40 community pharmacies in Dublin found that the mean number of prescriptions dispensed per hour was 7.7. Differences in the hourly dispensing rate were found between days of the week and parts of the day. Pharmacies with computerised dispensing dispensed a mean of 11.8 items per hour compared to 6.0 items per hour for those without computers. Prescriptions dispensed free to eligible patients accounted for 39% of all prescriptions.

Research paper thumbnail of A study of community pharmacy practice, 1: Pharmacists work patterns

Research paper thumbnail of The influence of polyvinylpyrrolidone on the dissolution properties of hydroflumethiazide

Journal of Pharmacy and Pharmacology, Oct 1, 1975

Research paper thumbnail of An Investigation Into Machine Learning Solutions Involving Time Series Across Different Problem Domains

Research paper thumbnail of Clofazimine

Analytical Profiles of Drug Substances and Excipients, 1992

Research paper thumbnail of Comparative in vivo evaluation of different delivery systems for the pulmonary administration of salmon calcitonin

Research paper thumbnail of A study of community pharmacy practice 1

Research paper thumbnail of Spray drying of budesonide, formoterol fumarate and their composites—I. Physicochemical characterisation

International Journal of Pharmaceutics, Feb 1, 2009

The objective of this work was to examine the physicochemical properties of spray dried budesonid... more The objective of this work was to examine the physicochemical properties of spray dried budesonide, formoterol fumarate and their mixtures at two different weight ratios: 100:6 and 400:6 of budesonide and formoterol fumarate, respectively. A comparison of the thermal properties, crystalline/amorphous nature and particle size of the starting micronised as well as processed materials was carried out. The micronised drugs on their own and the physical mixtures were crystalline in contrast to the spray dried counterparts which were shown to be amorphous. The glass transition temperatures (T(g)s) of the processed actives were determined and appeared at 89.5 and 88 degrees C for budesonide and formoterol fumarate, respectively. As for the spray dried composites, an indication of miscibility and/or interactions between the components was indicated by differential scanning calorimetry and infrared analysis. The spray drying in all cases resulted in smooth, spherical microparticles of sizes suitable for inhalation.

Research paper thumbnail of Reviewers for International Journal of Pharmaceutics

International Journal of Pharmaceutics, 2003

Research paper thumbnail of Irish Society of Gastroenterology

Irish Journal of Medical Science - IRISH J MED SCI, 1993

LAPAROSCOPIC APPENDICETOMY-IN1TIAL EXPERIENCE WITH 65 CASES. J. Coleman, H. TroidL J. Deasy, D. B... more LAPAROSCOPIC APPENDICETOMY-IN1TIAL EXPERIENCE WITH 65 CASES. J. Coleman, H. TroidL J. Deasy, D. Bouchier Hayes. Departments Surgery University Hospital Cologne and Beaumont Hospital, Royal College of Surgeons in Ireland. The advent of minimal ...

Research paper thumbnail of A study of pharmacy practice. Non-prescribed medicines sales and counselling 3

Research paper thumbnail of Encyclopedia of Pharmaceutical Science and Technology, Fourth Edition

Encyclopedia of Pharmaceutical Science and Technology, Fourth Edition, 2013

Research paper thumbnail of A Numerical Model of a Drug Particle Dissolving in a Dissolution Test Apparatus

PAMM, 2009

The dissolving compact, or tablet, is the most widely used method of drug delivery. Dissolution t... more The dissolving compact, or tablet, is the most widely used method of drug delivery. Dissolution tests are used to ensure consistency during tablet manufacture, to assess the dissolution characteristics of a particular tablet design, to establish in vitro/in vivo correlations, and to predict how the drug will perform in the body. Dissolution tests also form a part of the drug approval process. The United States Pharmacopeia (USP) Type 2 Paddle Dissolution Apparatus,from here on referred to as the USP apparatus, is a standard dissolution test device, used by the Food and Drug Administration (FDA)and the pharmaceutical industry. Although the USP apparatus is much used, detailed theoretical descriptions of its characteristics are still not well developed. This work considers one possible end state of a dissolving tablet, i.e. fragmentation into small particles with dissolution continuing from the disintegrated solid masses. A framework for calculating the motion of and mass transfer from a drug particle moving through the USP apparatus is outlined. Calculations demonstrate that small particles move with the USP apparatus flow and that, for small particles below a critical diameter, natural convection and radial diffusion dominate, i.e. forced convection effects can be neglected for small particles.

Research paper thumbnail of An Analysis of Drug Dissolution Rates in the USP 24 Type 2 Apparatus

PAMM, 2009

This paper applies boundary layer theory to the process of drug dissolution in the USP 24, Type 2... more This paper applies boundary layer theory to the process of drug dissolution in the USP 24, Type 2 Apparatus. The mass transfer rate from the top flat surface of a compact in various positions within the device is evaluated by means of a Pohlhausen integral method.

Research paper thumbnail of Impact of alternative solid state forms and specific surface area of high-dose, hydrophilic active pharmaceutical ingredients on tabletability

Molecular Pharmaceutics, 2013

In order to investigate the effect of using different solid state forms and specific surface area... more In order to investigate the effect of using different solid state forms and specific surface area (TBET) of active pharmaceutical ingredients on tabletability and dissolution performance, the mono-and dihydrated crystalline forms of chlorothiazide sodium and chlorothiazide potassium (CTZK) salts were compared to alternative anhydrous and amorphous forms, as well as to amorphous microparticles of chlorothiazide sodium and potassium which were produced by spray drying and had a large specific surface area. The tablet hardness and tensile strength, porosity and specific surface area of singlecomponent, convex tablets prepared at different compression pressures were characterised. Results confirmed the complexity of the compressibility mechanisms. In general it may be concluded that factors such as solid-state form (crystalline vs. amorphous), type of hydration (presence of interstitial molecules of water, dehydrates) or specific surface area of the material have a direct impact on the tabletability of the powder. It was observed that, for powders of the same solid state form, those with a larger specific surface area compacted well, and better than powders of a lower surface area, even at relatively low compression pressures. Compacts prepared at lower compression pressures from high surface area porous microparticles presented the shortest times to dissolve, when compared with compacts made of equivalent materials, which had to be compressed at higher compression pressures in order to obtain satisfactory compacts. Therefore, NPMP materials may be considered as suitable for direct compaction and possibly for inclusion in tablet formulations as bulking agents, APIs, carriers or binders due to their good compactibility performance.

Research paper thumbnail of In vitro analysis of the release of incorporated agents from sodium caseinate microspheres

Journal of Microencapsulation, 1997

Drug loaded microspheres were successfully prepared using the dairy protein, sodium caseinate (SC... more Drug loaded microspheres were successfully prepared using the dairy protein, sodium caseinate (SC), as the carrier material and containing hydrochlorothiazide, eosin, patent blue violet and sodium salicylate. The morphology of the microspheres varied depending on the incorporated material. Release of the incorporated agents from these systems was rapid with over 90% release in each case within 1 h. Further drug release occurred at a greatly reduced rate with a certain proportion of the drug loading appearing to be indefinitely entrapped within some of the microspheres. The drug release profiles were poorly described using the square root of time and Sinclair and Peppas equations but were well described by a biexponential equation. Analysis of the parameter estimates from the biexponential equation indicated that the initial rapid release phase was essentially completed within 5 min for all but the eosin microsphere systems and this timeframe was of the same order of magnitude as that found for the initial swelling of these microsphere systems as analysed by swelling studies using optical microscopy. Considering both the swelling study and the results from the release experiments, it seems likely that addition of SC microspheres to aqueous media results in immediate hydration and swelling. This process facilitates the rapid diffusional passage of water soluble drugs through the swollen and hydrated microsphere matrix, with drug release occurring almost unhindered unless other factors favour the retention of the incorporated agent with the microsphere.

Research paper thumbnail of Comparison of the physicochemical properties of the N-(2-hydroxyethyl) pyrrolidine, diethylamine and sodium salt forms of diclofenac

International Journal of Pharmaceutics, Jul 1, 2001

ABSTRACT

Research paper thumbnail of Temperature dependence and thermodynamics of partitioning of clofazimine analogues in the n-octanol/water system

International Journal of Pharmaceutics, 1990

International Journal of Pharmaceutics, 58 (1990) 107-113 Elsevier UP 01962 107 Temperature depen... more International Journal of Pharmaceutics, 58 (1990) 107-113 Elsevier UP 01962 107 Temperature dependence and thermodynamics of partitioning of clofazimine analogues in the ^-octanol/water system John M. Quigley Khairi MS Fahelelbom Richard F. Timoney 1 and Owen I. ...

Research paper thumbnail of Particle engineering of materials for oral inhalation by dry powder inhalers. I—Particles of sugar excipients (trehalose and raffinose) for protein delivery

International Journal of Pharmaceutics, Feb 28, 2011

Research paper thumbnail of Erratum to: In vitro evaluation physiological availability of aspirin tablets

Irish Journal of Medical Science, May 1, 1970

Research paper thumbnail of A study of community pharmacy practice, 2: Prescription Dispensing

An observational study of prescription dispensing in 40 community pharmacies in Dublin found that... more An observational study of prescription dispensing in 40 community pharmacies in Dublin found that the mean number of prescriptions dispensed per hour was 7.7. Differences in the hourly dispensing rate were found between days of the week and parts of the day. Pharmacies with computerised dispensing dispensed a mean of 11.8 items per hour compared to 6.0 items per hour for those without computers. Prescriptions dispensed free to eligible patients accounted for 39% of all prescriptions.

Research paper thumbnail of A study of community pharmacy practice, 1: Pharmacists work patterns

Research paper thumbnail of The influence of polyvinylpyrrolidone on the dissolution properties of hydroflumethiazide

Journal of Pharmacy and Pharmacology, Oct 1, 1975

Research paper thumbnail of An Investigation Into Machine Learning Solutions Involving Time Series Across Different Problem Domains

Research paper thumbnail of Clofazimine

Analytical Profiles of Drug Substances and Excipients, 1992

Research paper thumbnail of Comparative in vivo evaluation of different delivery systems for the pulmonary administration of salmon calcitonin

Research paper thumbnail of A study of community pharmacy practice 1

Research paper thumbnail of Spray drying of budesonide, formoterol fumarate and their composites—I. Physicochemical characterisation

International Journal of Pharmaceutics, Feb 1, 2009

The objective of this work was to examine the physicochemical properties of spray dried budesonid... more The objective of this work was to examine the physicochemical properties of spray dried budesonide, formoterol fumarate and their mixtures at two different weight ratios: 100:6 and 400:6 of budesonide and formoterol fumarate, respectively. A comparison of the thermal properties, crystalline/amorphous nature and particle size of the starting micronised as well as processed materials was carried out. The micronised drugs on their own and the physical mixtures were crystalline in contrast to the spray dried counterparts which were shown to be amorphous. The glass transition temperatures (T(g)s) of the processed actives were determined and appeared at 89.5 and 88 degrees C for budesonide and formoterol fumarate, respectively. As for the spray dried composites, an indication of miscibility and/or interactions between the components was indicated by differential scanning calorimetry and infrared analysis. The spray drying in all cases resulted in smooth, spherical microparticles of sizes suitable for inhalation.

Research paper thumbnail of Reviewers for International Journal of Pharmaceutics

International Journal of Pharmaceutics, 2003

Research paper thumbnail of Irish Society of Gastroenterology

Irish Journal of Medical Science - IRISH J MED SCI, 1993

LAPAROSCOPIC APPENDICETOMY-IN1TIAL EXPERIENCE WITH 65 CASES. J. Coleman, H. TroidL J. Deasy, D. B... more LAPAROSCOPIC APPENDICETOMY-IN1TIAL EXPERIENCE WITH 65 CASES. J. Coleman, H. TroidL J. Deasy, D. Bouchier Hayes. Departments Surgery University Hospital Cologne and Beaumont Hospital, Royal College of Surgeons in Ireland. The advent of minimal ...

Research paper thumbnail of A study of pharmacy practice. Non-prescribed medicines sales and counselling 3

Research paper thumbnail of Encyclopedia of Pharmaceutical Science and Technology, Fourth Edition

Encyclopedia of Pharmaceutical Science and Technology, Fourth Edition, 2013

Research paper thumbnail of A Numerical Model of a Drug Particle Dissolving in a Dissolution Test Apparatus

PAMM, 2009

The dissolving compact, or tablet, is the most widely used method of drug delivery. Dissolution t... more The dissolving compact, or tablet, is the most widely used method of drug delivery. Dissolution tests are used to ensure consistency during tablet manufacture, to assess the dissolution characteristics of a particular tablet design, to establish in vitro/in vivo correlations, and to predict how the drug will perform in the body. Dissolution tests also form a part of the drug approval process. The United States Pharmacopeia (USP) Type 2 Paddle Dissolution Apparatus,from here on referred to as the USP apparatus, is a standard dissolution test device, used by the Food and Drug Administration (FDA)and the pharmaceutical industry. Although the USP apparatus is much used, detailed theoretical descriptions of its characteristics are still not well developed. This work considers one possible end state of a dissolving tablet, i.e. fragmentation into small particles with dissolution continuing from the disintegrated solid masses. A framework for calculating the motion of and mass transfer from a drug particle moving through the USP apparatus is outlined. Calculations demonstrate that small particles move with the USP apparatus flow and that, for small particles below a critical diameter, natural convection and radial diffusion dominate, i.e. forced convection effects can be neglected for small particles.

Research paper thumbnail of An Analysis of Drug Dissolution Rates in the USP 24 Type 2 Apparatus

PAMM, 2009

This paper applies boundary layer theory to the process of drug dissolution in the USP 24, Type 2... more This paper applies boundary layer theory to the process of drug dissolution in the USP 24, Type 2 Apparatus. The mass transfer rate from the top flat surface of a compact in various positions within the device is evaluated by means of a Pohlhausen integral method.

Research paper thumbnail of Impact of alternative solid state forms and specific surface area of high-dose, hydrophilic active pharmaceutical ingredients on tabletability

Molecular Pharmaceutics, 2013

In order to investigate the effect of using different solid state forms and specific surface area... more In order to investigate the effect of using different solid state forms and specific surface area (TBET) of active pharmaceutical ingredients on tabletability and dissolution performance, the mono-and dihydrated crystalline forms of chlorothiazide sodium and chlorothiazide potassium (CTZK) salts were compared to alternative anhydrous and amorphous forms, as well as to amorphous microparticles of chlorothiazide sodium and potassium which were produced by spray drying and had a large specific surface area. The tablet hardness and tensile strength, porosity and specific surface area of singlecomponent, convex tablets prepared at different compression pressures were characterised. Results confirmed the complexity of the compressibility mechanisms. In general it may be concluded that factors such as solid-state form (crystalline vs. amorphous), type of hydration (presence of interstitial molecules of water, dehydrates) or specific surface area of the material have a direct impact on the tabletability of the powder. It was observed that, for powders of the same solid state form, those with a larger specific surface area compacted well, and better than powders of a lower surface area, even at relatively low compression pressures. Compacts prepared at lower compression pressures from high surface area porous microparticles presented the shortest times to dissolve, when compared with compacts made of equivalent materials, which had to be compressed at higher compression pressures in order to obtain satisfactory compacts. Therefore, NPMP materials may be considered as suitable for direct compaction and possibly for inclusion in tablet formulations as bulking agents, APIs, carriers or binders due to their good compactibility performance.