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Biomedical subjects

A Brindley

Publications and source records attributed to A Brindley.

6 recordsLinked to original sources
PubMed1999

The chlorofluorocarbon to hydrofluoroalkane transition: the effect on pressurized metered dose inhaler suspension stability.

The phase out of chlorofluorocarbon (CFC) propellants has necessitated the reformulation of pressurized metered dose inhalers (pMDIs) with hydrofluoroalkane (HFA) propellants. One of the main challenges has been that conventional surfactants used for CFC-based pMDIs were not soluble in HFAs. Since one of the main aims of a pMDI is to deliver a reproducible dose of medication to the patient, it is vital that, for suspension-type pMDI formulations, the suspension is stabilized sufficiently for a reproducible dose to be delivered. A new technique has been developed that measures suspension stability more objectively than before. This technique, optical suspension characterization, was used to compare the performance of different formulations of respiratory drugs in HFAs. The optical suspension characterization data were correlated with conventional analytic techniques for the determination of the stability of the suspension formulation.

Aerosol Propellants↗
PubMed1994

Polystyrene-poly (ethylene glycol) (PS-PEG2000) particles as model systems for site specific drug delivery. 2. The effect of PEG surface density on the in vitro cell interaction and in vivo biodistribution.

The effect of differing densities of poly (ethylene glycol-2000) (PEG2000) at the particle surface of polystyrene-poly (ethylene glycol-2000) (PS-PEG2000) particles was assessed in terms of hydrophobic interaction chromatography (HIC) and the in vitro and in vivo behaviour of the particles. The particles, with different surface densities of PEG, were prepared by varying the copolymerizing reaction of styrene with a PEG macromonomer. There is a clear relationship between the surface density of PEG as determined by X-ray photoelectron spectroscopy and surface hydrophobicity as assessed by hydrophobic interaction chromatography (HIC). Similarly, the interaction of the particles with non-parenchymal liver cells in in vitro studies was shown to decrease as the surface density of PEG increases. The in vivo study investigating the biodistribution of the PS-PEG particles after intravenous injection into rats reveals that a relationship exists between the surface density of PEG and the extent to which the particles remain in the circulation, avoiding recognition by the reticuloendothelial system. Particles with the higher surface densities show increased circulatory times which compared well with data for particles prepared with the surface adsorbed PEO-PPO block copolymer, Poloxamine 908.

Animals↗
PubMed1994

The characterisation of inhalation devices by an inhalation simulator: The Electronic Lung.

The Electronic Lung is an inhalation simulator designed for the characterisation of breath-actuated inhalation devices. It enables the in-vitro evaluation of devices under conditions that have been produced in-vivo. Data generated on the Serevent Diskhaler inhaler have highlighted the reproducibility of particle size distribution of drug delivered from the device over a range of inhalation parameters.

Computer Simulation↗
PubMed1992

Early life stage survival of striped bass in the Delaware River, USA.

Four 96-h in situ bioassays were conducted on or near the striped bass spawning grounds in the Delaware River within the States of Delaware, New Jersey and Pennsylvania, USA during 1989 to determine if water quality was sufficient to support larval survival. Tests were accomplished by holding 500 striped bass yolk-sac larvae in each of two 75 L chambers at four locations in the river ranging from north of Philadelphia, PA to Salem, NJ and at one location in the Chesapeake and Delaware Canal. Survival varied significantly among stations; highest survival was in the Chesapeake and Delaware Canal, where it averaged more than 50%. Lowest survival occurred at the station near Salem, NJ, approximately 30 km downriver of the primary spawning grounds, where less than 1% of the larvae survived in any of the tests. Survival at stations closest to the primary spawning grounds was weather-dependent; survival was over 47% during periods of little rainfall, but only 11% following periods of higher than average rainfall.

Animals↗