Characterisation of Aerosols Generated by Pressurised Metered Dose Inhalers

For over half a century, pressurised metered dose inhalers (pMDIs) have been the<br/>most sold inhaler devices for the treatment of lung diseases. However, they suf-<br/>fer from signicant drug deposition in the mouth and throat, mainly due to the<br/>aerosolisation of large and fast-moving droplets. This causes a high occurrence of<br/>side eects and is wasteful of drug. They are also aected by a low consistency of<br/>dosing and as a result users might not benet from maximal device eciencies.<br/>The hypothesis of this work was that the performance of pMDIs is dependent on<br/>numerous factors which might alter the characteristics of their particles and their<br/>deposition location within the respiratory tract. For example, it was thought that<br/>the variations in actuation forces of pMDIs and temperatures at which they are<br/>used might contribute to their low consistency.<br/>A one-dimensional Matlab computational model was developed in order to calcu-<br/>late spray properties at the exit of the device where experimental measurements<br/>are dicult to conduct. The model simulated the discharge of pure HFA134a<br/>formulations and HFA134a-based suspension formulations containing uticasone<br/>propionate; the latter representing a commercially available formulation.<br/>The results showed that the actuation force of a\healthy" adult led to a higher<br/>valve opening rate and to the aerosolisation of smaller droplets than the actuation<br/>force provided by a \weak" adult. The model also showed that an increase of<br/>temperature led to the aerosolisation of smaller droplets. The model was validated using impaction measurements and laser techniques.<br/>The next generation impactor (NGI) experiments revealed the importance of actu-ation forces on the throat deposition. Automated actuation forces with high valve opening rates led to a lower throat deposition than a manual actuation force with low valve opening rate.

Name dc:type.qualificationname

Doctor of Philosophy

Level dc:type.qualificationlevel

Doctoral Thesis

Grantor dc:publisher.institution

King's College London

Year dc:date.issued

2013

Author dc:creator

• Harang, Marie

Advisors dc:contributor.advisor

• Lee, Ka-Lok Carroll
• Royall, Paul Garry

Language dc:language

eng

Identifier

oai:kclpure.kcl.ac.uk:studenttheses/57ce7267-ffbe-4aad-8654-c7822e89b7a0

OAI identifier oai:identifier

oai:kclpure.kcl.ac.uk:studenttheses/57ce7267-ffbe-4aad-8654-c7822e89b7a0