Paul M Young

Senior Lecturer in Pharmaceutics

Qualifications

BSc (Hons) W.England PhD Bath

Contact Details

University of Sydney
Phone: +61 2 9036 7035
Fax: +61 2 9351 4391
Email:
Room 501
Badham Building A16
The University of Sydney
NSW 2006 Australia

Research Interests

A general interest into all areas of Pharmaceutical Technology, including solid dosage forms, inhalation, nasal delivery, colloidal science, controlled release and surface/interfacial science

Specific areas of current research are highlighted below:

Respiratory Drug Delivery

Dry powder inhalation (DPI)
The delivery of dry particles to the respiratory tract has become a popular delivery route of local and systemic molecules. In order to achieve a therapeutic outcome, the dry particulates have to have a diameter of less then 5 microns to avoid impaction in the upper airways. Particles of this size tend to be highly adhesive/cohesive and therefore particle interactions in these systems play a major role on the aerosolisation performance.

Current research projects within this area include correlating the force of drug-excipient interaction, to the aerosolisation performance in DPI systems. Specifically, physical-chemical factors such as amorphous content, surface morphology, roughness and the presence of active sites are under investigation. Furthermore, the influence of formulation variables, such as excipient material and the presence ternary formulation components (left pane, above) have been studied.

Apart from conventional in vitro techniques (NGI, ACI etc), the formulations are characterised utilising ultra-sensitive methodology such as atomic force microscopy, colloid probe microscopy and electrostatic aerosol characterisation (such as the electrostatic low pressure impactor, (right pane, above)).

Application of these novel methodologies to aerosol science gives us a greater incite into particle interactions and allows us to predict aerosol performance.

Pressurised metered dose inhalers (pMDI)

The formulation of drug suspensions and solutions in liquid propellants is of current interest. For example, modification of pMDI component material may reduce particle adhesion, internal losses or increase chemical stability in solution based systems.

In addition, the solubility of pharmaceutical compounds in non-aqueous propellants is of interest with relation to both solution and suspension based medicaments.

As with the DPI research program, a combination of novel and conventional techniques are used to probe the physical-chemical properties of these systems. Current research projects include assessment of particle interactions in non-aqueous media using atomic force microscopy, particulate formulation an aggregation during aerosolisation, plume characterisation and theoretical modelling of the aerosolisation process.

Controlled release respiratory therapy

A significant disadvantage of respiratory delivery mechanisms is the short duration of clinical effect, with most medicaments requiring delivery up to four times daily. In addition, since asthma symptoms exhibit a diurnal rhythm, the ideal treatment should be effective in preventing bronchospasm while the patient is asleep during the night.

Subsequently, the potential of controlling the release kinetics of a medicament after deposition in the respiratory tract is an attractive proposition.

Currently, we are focused on particle engineering of powders with controlled release profiles for the delivery of both local and systemic medicines to the respiratory tract. In parallel we are developing methodologies for the in vitro analysis of these systems and are correlating the performance and release profiles with different production methodologies.

The surface physical-chemical properties of a pharmaceutical solid have significant influence on pharmaceutical formulation parameters (such as solubility, adhesion/cohesion, stability, sorption capacity etc). Arguably, when dealing with particulate based formulations the surface physical-chemical properties dominant product performance.

Subsequently, we are currently investigating the physical and chemical nature of surfaces and interfaces with a view to predicting formulation behaviour in the solid state.

Current research is focussed on investigating the nature of amorphous form in predominately crystalline materials and predicting surface chemistry in amorphous and crystalline systems.

Techniques utilised include vapour sorption, inverse gas chromatography, atomic force microscopy, computational chemistry and molecular modelling.

Excipients

The preparation and performance of a solid dosage form (e.g. tablets, capsules etc.) will be dependent on the functionality of the excipients used. We are currently investigating how the internal and surface structure of raw/modified starch, cellulose and sugar based excipients influence performance factors such as powder flow, content uniformity, compactability and dissolution.

Modified release and matrix based tablets

Currently we are evaluating novel polymer controlled release matrix systems and investigating how the internal structure of such systems influences the in vitro dissolution rates

Publications

2008-2009

1. Parlati C.,, Colombo, P., Buttini, F.,Young, P.M. Adi, H., Ammit, A.J. Traini, D. Pulmonary Spray Dried Powders of Tobramycin Containing Sodium Stearate to Improve Aerosolization Efficiency. Pharmaceutical Research (Accepted 2009)
2. Young, P.M., Adi, H., Patel, T., Law, K., Rogueda, P., Traini, D. (2009) The influence of micronised particulates on the aerosolisation of pressurised metered dose inhalers. Journal of Aerosol Science Vol 40. 324-337
3. Young, P.M., Kwok, P., Adi, H., Chan, H-K., Traini, D. (2009) Lactose composite particles for improved respiratory delivery. Pharmaceutical Research Vol 26. 802-810
4. Hoe, S., Young, P.M., Chan, H-K., Traini, D. (2009) Investigation of the particle sizing and electrostatic characterisation capabilities of the electrical Next Generation Impactor (eNGI) for the study of pressurized metered dose inhalers. Pharmaceutical Research Vol 26. 431-437
5. Traini, D., Jones, A.S., Nguen, K., Young, P.M. (2008) Microstructural analysis of porous composite materials; dynamic imaging of drug dissolution and diffusion through porous matrices. AAPS Journal Vol 10. 560-564
6. Salama, R., Traini, D., Chan, H-K., Sung, A., Ammit, A.J., Young, P.M. Preparation and evaluation of controlled release microparticles for respiratory protein therapy. Journal of Pharmaceutical Science (Accepted September 2008)
7. Adi, S., Adi, H., Chan, H-K., Young, P.M., Traini, D., Yang, R., Yu, A. (2008) Scanning white light interferometry as a novel technique to quantify the surface roughness of particles used in inhalation medicine. Langmuir Vol 24. 11307-11312
8. Das, S., Larson, I., Young, P.M., Stewart, P.J. Influence of storage relative humidity on the dispersion of Salmeterol Xinafoate powders for inhalation. Journal of Pharmaceutical Sciences (Accepted June 2008)
9. Adi, H., Adi, S., Traini, D., Chan, H-K., Young, P.M. (2008) Micro-particle corrugation, adhesion and inhalation aerosol efficiency. European Journal of Pharmaceutics Vol 35. 12-18
10. Salama, R., Traini, D., Chan, H-K., Young, P.M. (2008) Preparation and Characterisation of co-sprayed drug-polymer micro particles for inhalation 2: Evaluation of in vitro release profiling methodologies for controlled release respiratory aerosols. European Journal of Pharmaceutics and Biopharmaceutics. European Journal of Pharmaceutics and Biopharmaceutics Vol 70, 145-152
11. Steele, D.F., Moreton, R.C., Staniforth, J.N., Young, P.M., Tobyn, M.J., Edge, S. Surface energy of microcrystalline cellulose determined by capillary intrusion and inverse gas chromatography. AAPS Journal (accepted March 2008)
12. Hoe, S., Rogueda, P., Young, P.M., Traini. (2008) Determination of ultrasonic reference parameters for the characterisation of pressurised metered dose inhaler suspension formulations. AAPS PharmSci. Vol 9, 605-611
13. Salama, R., Hoe, S., Adi, H., Traini, D., Chan, H-K., Young, P.M. (2008) Preparation and Characterisation of co-sprayed drug-polymer micro particles for inhalation 1: influence of polymer concentration on physical and in vitro characteristics. Journal of controlled release. European Journal of Pharmaceutics and Biopharmaceutics. Vol 69, 486-495
14. Traini, D., Thielmann, F., Acharya, M., Jarring, K., Young, P.M. (2008) The influence of lactose pseudo-polymorphism on salbutamol sulphate -lactose interactions in DPI formulations. Drug Development and Industrial Pharmacy. Vol 34, 992 - 1001
15. Jones, M.D., Young, P.M., Traini, D., Shur, J., Edge, S., Price,R. (2008) The use of atomic force microscopy to study the conditioning of micronised budesonide. International Journal of Pharmaceutics Vol 357, 314-317
16. Adi, H., Young, P.M., Chan, H-K., Stewart, P.J., Agus, H., Traini, D. (2008) Co-spray dried antibiotics for dry powder lung delivery. Journal of Pharmaceutical Sciences. Vol 97, 3356-3366
17. Adi, H., Larson, I., Chiou, H., Young, P.M., Traini, D., Stewart P.J. (2008) Role of agglomeration in the dispersion of salmeterol xinafoate from mixtures for inhalation with differing drug to fine lactose ratios. Journal of Pharmaceutical Sciences. Vol 97, 3140-3152
18. Adi, H., Traini, D., Chan, H-K., Young,P.M. (2008) The influence of drug morphology on the aerosolisation efficiency of dry powder inhaler formulations. Journal of Pharmaceutical Sciences. Vol 97, 2780-2788
19. Young, P.M., Price, R. (2008) Comparative measurement of pressurised metered dose inhaler (pMDI) stem displacement. Drug Development and Industrial Pharmacy Vol 34, 90-94
20. Young, P.M., Roberts, D., Chiou, G., Rae, W., Chan, H-K., Traini, D. (2008) Composite carriers improve the aerosolisation efficiency of drugs for respiratory delivery. Journal of Aerosol Science Vol 39, 82-93