DOI
https://doi.org/10.25772/W6SV-FQ87
Defense Date
2012
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Pharmaceutical Sciences
First Advisor
Peter Byron
Abstract
This research was aimed at the development and validation of new in vitro methods capable of predicting in vivo drug deposition from dry powder inhalers, DPIs, in lung-normal human adults. Three physical models of the mouth, throat and upper airways, MT-TB, were designed and validated using the anatomical literature. Small, medium and large versions were constructed to cover approximately 95% of the variation seen in normal adult humans of both genders. The models were housed in an artificial thorax and used for in vitro testing of drug deposition from Budelin Novolizer DPIs using a breath simulator to mimic inhalation profiles reported in clinical trials of deposition from the same inhaler. Testing in the model triplet produced results for in vitro total lung deposition (TLD) consistent with the complete range of drug deposition results reported in vivo. The effect of variables such as in vitro flow rate were also predictive of in vivo deposition. To further assess the method’s robustness, in vitro drug deposition from 5 marketed DPIs was assessed in the “medium” MT-TB model. With the exception of Relenza Diskhaler, mean values for %TLD+SD differed by only < 2% from their literature in vivo. The relationship between inhaler orientation and in vitro regional airway deposition was determined. Aerosol drug deposition was found to depend on the angle at which an inhaler is inserted into the mouth although the results for MT deposition were dependent on both the product and the formulation being delivered. In the clinic, inhalation profiles were collected from 20 healthy inhaler naïve volunteers (10M, 10F) before and after they received formal inhalation training in the use of a DPI. Statistically significant improvements in Peak Inhalation Flow Rate (PIFR) and Inhalation Volume (V) were observed following formalized training. The shapes of the average inhalation profiles recorded in the clinic were found to be comparable to the simulated profiles used in the in vitro deposition studies described above. In conclusion, novel in vitro test methods are described that accurately predict both the average and range of aerosol airway drug deposition seen from DPIs in the clinic.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
May 2012