Performance of two different types of inhalers. Influence of flow and spacer on emitted dose and aerodynamic characterisation.

Abstract

This thesis is based around examination of three mainstream inhaled drugs Formoterol, Budesonide and Beclomethasone for treatment of asthma and COPD. The areas investigated are these which have been raised in reports and studies, where there are concern, for drug use and assessment of their use. In reporting this work the literature study sets out a brief summary of the background and anatomy and physiology of the respiratory system and then discuses the mechanism of drug deposition in the lung, as well as the methods of studying deposition and pulmonary delivery devices. This section includes the basis of asthma and COPD and its treatment. In addition, a short section is presented on the role of the pharmacist in improving asthma and COPD patient¿s care. Therefore the thesis is divided into 3 parts based around formoterol, budesonide and beclomethasone. In the first case the research determines the in-vitro performance of formoterol and budesonide in combination therapy. In the initial stage a new rapid, robust and sensitive HPLC method was developed and validated for the simultaneous assay of formoterol and the two epimers of budesonide which are pharmacologically active. In the second section, the purpose was to evaluate the aerodynamic characteristics for a combination of formoterol and the two epimers of budesonide at inhalation flow rates of 28.3 and 60 L/min. The aerodynamic characteristics of the emitted dose were measured by an Anderson cascade impactor (ACI) and the next generation cascade impactor (NGI). In all aerodynamic characterisations, the differences between flow rates 28.3 and 60 were statistically significant in formoterol, budesonide R and budesonide S, while the differences between ACI and NGI at 60 were not statistically significant. Spacers are commonly used especially for paediatric and elderly patients. However, there is considerable discussion about their use and operation. In addition, the introduction of the HFAs propellants has led to many changes in the drug formulation characteristics. The purpose of the last section is to examine t h e performance of different types of spacers with different beclomethasone pMDIs. Also, it was to examine the hypothesis of whether the result of a specific spacer with a given drug/ brand name can be extrapolated to other pMDIs or brand names for the same drug. The results show that there are different effects on aerodynamic characterisation and there are significant differences in the amount of drug available for inhalation when different spacers are used as inhalation aids. Thus, the study shows that the result from experiments with a combination of a spacer and a device cannot be extrapolated to other combination.