DRUG NANOSIZING USING MICROFLUIDIC REACTORS HSM ALI PhD 2010

246 Pages·2011·5.09 MB·English

Drug Nanosizing Using Microfluidic Reactors

DRUG NANOSIZING USING MICROFLUIDIC REACTORS

H. S. M. ALI

PhD

2010

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Drug Nanosizing Using Microfluidic Reactors

DRUG NANOSIZING USING MICROFLUIDIC REACTORS

Development, characterisation and evaluation of corticosteroids nano-
sized particles for optimised drug delivery

Hany Saleh Mohamed ALI

Submitted for the degree of Doctor of Philosophy

Department of Pharmacy

University of Bradford

2010
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Drug Nanosizing Using Microfluidic Reactors

Drug Nanosizing Using Microfluidic Reactors

Hany Saleh Mohamed Ali

Keywords: Microfluidics; solubility; nanoprecipitation; hydrocortisone; prednisolone;
budesonide; ANN modelling; nebulization; ocular; bioavailability

Abstract

Over recent years the delivery of nanosized drug particles has shown potential in
improving bioavailability. Drug nanosizing is achieved by “top-down” and by “bottom-
up” approaches. Owing to limitations associated with the top-down techniques, such as
high energy input, electrostatic effects, broad particle size distributions and
contamination issues, great interest has been directed to alternative bottom up
technologies.
In this study, the hypothesis that microreactors can be used as a simple and cost-
effective technique to generate organic nanosized products is tested using three steroids
(hydrocortisone, prednisolone and budesonide). Arrested antisolvent nanoprecipitation
using ethanol (solvent) and water (antisolvent) was conducted within the microreactors.
To enable experimental design for the microreactor studies, solubility profiles in
different ethanol-water combinations at 25 °C were explored. All three drugs’ solubility
increased with increasing ethanol concentration showing maxima at 80-90 % v/v
ethanol-water mixtures. Because of the complex multivariate microfluidic process,
artificial neural network modelling was then employed to identify the dominant
relationships between the variables affecting nanoprecipitation (as inputs) and the drug
particle size (as output). The antisolvent flow rate was found to have the major role in
directing drug particle size.
Based on these successful findings, the potential of preparing pharmaceutical
nanosuspensions using microfluidic reactors was researched. A hydrocortisone (HC)
nanosuspension (NS) was prepared by introducing the generated drug particles into an
aqueous solution of stabilizers stirred at high speed with a propeller mixer. A tangential
flow filtration system was then used to concentrate the prepared NS. Results showed
that a stable narrow sized HC NS of amorphous spherical particles 500 ± 64 nm
diameter and zeta potential −18 ± 2.84 mV could be produced.
The ocular bioavailability of a microfluidic precipitated HC NS (300 nm) was
assessed and compared to a similar sized, milled HC NS and HC solution as a control.
The precipitated and the milled NS achieved comparable AUC of 28.06 ± 4.08 and
0-9h
30.95 ± 2.2, respectively, significantly (P < 0.01) higher than HC solution (15.86 ± 2.7).
These results illustrate the opportunity to design sustained release ophthalmic
formulations.
Going nano via microfluidic precipitation was also exploited to tailor
budesonide (BD) NS for pulmonary administration. The in vitro aerosolization by
nebulization of a BD NS was studied in comparison with a commercial BD
microsuspension. Overall, the fine particle fraction generated from BD NS (56.88 ±
3.37) was significantly (P < 0.05) higher than the marketed BD (38.04 ± 7.81). The
mean mass aerodynamic diameter of BD NS aerosol (3.9 ± 0.48 µm) was significantly
smaller (P < 0.05) than the microsuspension (6.2 ± 1.09 µm) indicating improved
performance for BD NS.
In conclusion, findings of this study support the hypothesis of using microfluidic
nanoprecipitation as a promising and economical technique of drug nanosizing.
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Drug Nanosizing Using Microfluidic Reactors

List of Research Output

I. Published / submitted

Hany S.M. Ali, P. York and N. Blagden. Nanosizing of hydrocortisone using
microfluidic reactors. Journal of Pharmacy and Pharmacology 2008; Supplement 1,
A-36.

Hany S.M. Ali, Peter York and Nicholas Blagden. Preparation of hydrocortisone
nanosuspension through a bottom-up nanoprecipitation technique using
microfluidic reactors. International Journal of Pharmaceutics (2009) 375, 107-113.

Hany S.M. Ali, Nicholas Blagden, Peter York, Amir Amani and Toni Brook. Artificial
neural networks modelling the prednisolone nanoprecipitation in microfluidic
reactors. European Journal of Pharmaceutical Sciences (2009) 37, 514-522.

Hany S. M. Ali, Peter York, Nicholas Blagden, Shahla Soltanpour, William E. Acree,
Jr., and Abolghasem Jouyban. Solubility of Budesonide, Hydrocortisone, and
Prednisolone in Ethanol + Water Mixtures at 298.2 K. Journal of Chemical and
Engineering Data (2010) 55 (1), 578–582.

Hany S.M. Ali, Peter York, Nicholas Blagden and Amir Amani. Nanosizing and in
vitro characterization of budesonide dispersions prepared by microfluidic reactors.
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Drug Nanosizing Using Microfluidic Reactors

Journal of Aerosol Medicine and Pulmonary Drug Delivery. Abstracts from the
aerosol society drug delivery to the lungs 20 (in press).

Hany S.M. Ali, Peter York, Ahmed A.M. Ali and Nicholas Blagden. Hydrocortisone
nanosuspensions for ophthalmic delivery: A comparative study between
microfluidic nanoprecipitation and wet milling. Journal of Controlled Release (in
press).

Hany S.M. Ali, Peter York, Amir Amani and Nicholas Blagden. Bottom-up
microfluidic preparation and in-vitro evaluation of nano-budesonide suspensions
for pulmonary delivery (submitted manuscript).

II. Presented (poster/podium)

H. S. M. Ali, P. York and N. Blagden. Production of prednisolone nanoparticles
using microfluidic reactors. Emerging Pharmaceutical Scientists Conference for
students and post-doctoral researchers. AstraZeneca, Loughborough, April 3- 4,
2008.

H. S. M. Ali, P. York and N. Blagden. Nanosizing of hydrocortisone using
microfluidic reactors. British Pharmaceutical Conference, BPC 2008. Manchester,
September, 7-9, 2008.
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Drug Nanosizing Using Microfluidic Reactors

H. S. M. Ali, P. York and N. Blagden. Synthesis of hydrocortisone nano-sized
particles using a microfluidic platform. Research and Knowledge Transfer Showcase
Event, University of Bradford, November 19, 2008.

H. S. M. Ali, P. York and N. Blagden. Preparation of budesonide nanodispersions
for pulmonary delivery using microfluidic reactors. Inhalation 2009. Nottingham,
March 23-25, 2009 (oral presentation).

H. S. M. Ali, P. York, A. Amani and N. Blagden. Nanosizing and in-vitro
characterization of budesonide dispersions prepared by microfluidic reactors. Drug
Delivery to the Lungs 20. Edinburgh, December 8-11, 2009.

H. S. M. Ali, P. York and N. Blagden. Microfluidics in drug nanosizing. University of
Bradford, School of Life Science Research Event, March 23, 2010.

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Drug Nanosizing Using Microfluidic Reactors

Acknowledgements

Firstly, I would like to extend my most sincere thanks to my
academic supervisors Professor Peter York and Dr Nicholas Blagden for
their great support, excellent advice, endless encouragement and guidance
over the period of my study.
I would like also to acknowledge the financial support kindly provided
from the Egyptian Government (Ministry of High Education).
At University of Bradford, I’m grateful to the staff of IPI for
providing excellent research facilities and good environment. My deep
thanks to the past and present PhD students, especially, Dr Amir Amani, Dr
Ahmed Ali and members in office 1.13 for their appreciated assistance and
friendship.
Finally, I would like thank my family, my wife and my little kids
(Rouaa and Ahmed) for their continual love, support and encouragement in
my life.

Hany Ali

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Drug Nanosizing Using Microfluidic Reactors

I dedicate this thesis to:
My family,
My wife
(Sawsan)
And
My little kids
(Rouaa and Ahmed)
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Drug Nanosizing Using Microfluidic Reactors

Table of contents
Title page...........................................................................................................................I
Abstract............................................................................................................................II
List of Research Output...................................................................................................III
Acknowledgment............................................................................................................VI
Dedication......................................................................................................................VII
Table of Contents..........................................................................................................VIII
List of Tables...................................................................................................................XII
List of Figures.................................................................................................................XIII
List of Abbreviations and Symbols................................................................................XVI
1 General Introduction ......................................................................................... 1
1.1 Nanotechnology and drug delivery ....................................................................... 2
1.1.1 Introduction ................................................................................................ 2
1.1.2 Nanoparticulate drug delivery systems ...................................................... 3
1.1.3 Approaches for drug nanosizing ................................................................. 5
1.1.4 Going nano: benefits for drugs ................................................................. 16
1.1.5 Commercially available nanosized drug products .................................... 28
1.2 Challenges of nano-drug therapy ........................................................................ 29
1.3 Microfluidics ........................................................................................................ 30
1.3.1 Introduction .............................................................................................. 30
1.3.2 Microfluidics and laminar flow ................................................................. 31
1.3.3 Moving fluids in microreactors ................................................................. 32
1.3.4 Fabrication of microfluidic devices ........................................................... 32
1.3.5 Applications of microfluidics ..................................................................... 33
1.3.6 Crystallization ............................................................................................ 34
1.3.7 Supersaturation ......................................................................................... 34
1.3.8 Nucleation ................................................................................................. 36
1.3.9 Crystal growth ........................................................................................... 37
1.3.10 Microfluidics and crystallization ............................................................... 37
1.4 Aims and objectives of the thesis ....................................................................... 40
1.5 Thesis structure ................................................................................................... 44
2 Solubility Studies ............................................................................................. 45
2.1 Introduction ........................................................................................................ 46
2.1.1 Drug solubility ........................................................................................... 46
2.1.2 Aim of work in Chapter 2 .......................................................................... 48
2.2 Experimental ....................................................................................................... 49
2.2.1 Materials ................................................................................................... 49
2.2.2 Solubility measurement ............................................................................ 49
2.2.3 Apparatus and procedures ........................................................................ 50
2.2.4 Solubility modelling ................................................................................... 50
2.3 Results and discussion......................................................................................... 52
2.3.1 Calibration curves ..................................................................................... 52
2.3.2 Solubility studies ....................................................................................... 53
2.4 Conclusion ........................................................................................................... 58
3 Modelling of Microfluidic Nanoprecipitation Using Artificial Neural Networks . 59
3.1 Introduction ........................................................................................................ 60
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Drug Nanosizing Using Microfluidic Reactors

3.1.1 Artificial neural networks .......................................................................... 60
3.1.2 Network architecture ................................................................................ 62
3.1.3 Training neural networks .......................................................................... 64
3.1.4 Overtraining in artificial neural networks ................................................. 66
3.1.5 Artificial neural networks in pharmaceutical research ............................. 67
3.1.6 Aim of work in Chapter 3 .......................................................................... 68
3.2 Experimental ....................................................................................................... 69
3.2.1 Materials ................................................................................................... 69
3.2.2 Data mining tool ........................................................................................ 69
3.2.3 Microfluidic nanoprecipitation ................................................................. 70
3.2.4 Measurement of particle size ................................................................... 71
3.2.5 ANN modelling .......................................................................................... 72
3.2.6 Training parameters .................................................................................. 78
3.2.7 Predictability of trained models ................................................................ 79
3.3 Results and discussion......................................................................................... 80
3.3.1 Microfluidic precipitation .......................................................................... 80
3.3.2 Data analysis using ANNs .......................................................................... 81
3.3.3 Effects of the variables on the particle size .............................................. 84
3.3.4 Effect of antisolvent flow rate .................................................................. 85
3.3.5 Effect of solution flow rate ....................................................................... 86
3.3.6 Effect of different inlet angles .................................................................. 86
3.3.7 Effect of internal diameter of microreactors ............................................ 87
3.3.8 Effect of drug saturation level................................................................... 87
3.4 Conclusion ........................................................................................................... 92
4 Preparation of Hydrocortisone Nanosuspension by a Bottom-up Procedure
Using Microfluidic Reactors .................................................................................... 93
4.1 Introduction ........................................................................................................ 94
4.1.1 Pharmaceutical nanosuspensions ............................................................. 94
4.1.2 Manufacturing of drug nanosuspension ................................................... 94
4.1.3 Characterization of nanosuspension ........................................................ 94
4.1.4 Nanosuspension in drug delivery ............................................................ 100
4.1.5 Ostwald ripening and drug nanosupension ............................................ 101
4.1.6 Tangential flow filtration ......................................................................... 103
4.1.7 Aim of work in Chapter 4 ........................................................................ 104
4.2 Experimental ..................................................................................................... 105
4.2.1 Materials ................................................................................................. 105
4.2.2 Production of hydrocortisone nanosuspension ...................................... 105
4.2.3 Determination of the drug content ........................................................ 106
4.2.4 Concentration of nanosuspension .......................................................... 107
4.2.5 Particle size measurement ...................................................................... 107
4.2.6 Zeta potential measurement .................................................................. 107
4.2.7 Characterization of morphology of particles .......................................... 109
4.2.8 Differential scanning calorimetery analysis ............................................ 109
4.2.9 X-ray powder diffraction ......................................................................... 110
4.2.10 Physical Stability Study ............................................................................ 110
4.3 Results and discussion....................................................................................... 111
4.3.1 Preparation and stabilization of nanosuspension .................................. 111
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