Mass output and particle size distribution of glucocorticosteroids emitted from different inhalation devices depending on various inspiratory parameters.

Efficient inhalation therapy depends on successful delivery of the drug to the lung. The efficacy of drug delivery is not only influenced by the characteristics of the inhalation device, but also by the patient's handling of the device and by the inspiratory maneuver achieved through the device. We analyzed the output characteristics of three different chlorofluorocarbon (CFC)-free breath-actuated inhalers for inhaled glucocorticosteroids (BUD Turbohaler, FP Diskus/Accuhaler and HFA-BDP Autohaler, respectively). Mass output and particle size distribution of drug aerosol delivered by the inhalers were determined depending on different inhalation parameters in vitro using an Andersen cascade impactor. We found that, beside the peak inspiratory flow (PIF), other factors such as flow acceleration and inhalation volume also have significant effects on aerosol generation with respect to mass output and particle size distribution. Thus, these parameters should be taken into account when a suitable device for an individual patient is to be selected. The dependency on inspiratory parameters was most pronounced for the dry powder inhalers. The Turbohaler showed by far the highest variance in particle output (fine particle fraction ranging from 3.4% to 22.1% of label claim), whereas the Diskus was less dependent on variations in inhalation (10.6% to 18.5% of label claim). The most constant aerosol output was found for the Autohaler, which also released the highest fine particle fraction (43.1% to 56.6% of label claim).

Detection and selective dissociation of intact ribosomes in a mass spectrometer.

Intact Escherichia coli ribosomes have been projected into the gas phase of a mass spectrometer by means of nanoflow electrospray techniques. Species with mass/charge ratios in excess of 20,000 were detected at the level of individual ions by using time-of-flight analysis. Once in the gas phase the stability of intact ribosomes was investigated and found to increase as a result of cross-linking ribosomal proteins to the rRNA. By lowering the Mg(2+) concentration in solutions containing ribosomes the particles were found to dissociate into 30S and 50S subunits. The resolution of the charge states in the spectrum of the 30S subunit enabled its mass to be determined as 852,187 +/- 3,918 Da, a value within 0.6% of that calculated from the individual proteins and the 16S RNA. Further dissociation into smaller macromolecular complexes and then individual proteins could be induced by subjecting the particles to increasingly energetic gas phase collisions. The ease with which proteins dissociated from the intact species was found to be related to their known interactions in the ribosome particle. The results show that emerging mass spectrometric techniques can be used to characterize a fully functional biological assembly as well as its isolated components.