الفهرس 
Preparation and characterization of optimized miconazoleOnly 14 pages are availabe for public view
 |  | from | 32 |  |  |
| | | from | 32 | | |
Abstract
Pulmonary fungal infections have dramatically increased in the past few years due to the increase in the number of immunocompromised patients associated with the increase in the number of organ transplantations, HIV and patients receiving chemotherapy for malignancies. These patients lack the basic cellular defense mechanisms which make them more susceptible to less virulent organisms to which normal people are resistant such as Candida and Asperigillus spp.
Although being one of the earliest discovered antifungals, miconazole nitrate (MN) is still commonly used. Variations in its antifungal mechanisms of action make it a good candidate against different fungal infections. Being one of the azoles, it inhibits cytochrome P450, an essential enzyme for the biosynthesis of ergosterol, an essential component in the fungal cell wall. It also alters the phospholipids and triglycerides synthesis and inhibits the fungal oxidative enzymes leading to accumulation of the toxic H2O2 inside the fungal cell which eventually leads to its death.
In this thesis, our aim is to treat fungal infections in lungs by local pulmonary delivery using dry powder inhalers. These will ensure a high local drug concentration, decrease frequency of administration with an expected reduction of the required dose and hence side effects. The site of deposition of dry powder in the respiratory tract is controlled by the mass mean aerodynamic diameter (MMAD), where particles < 1μm move by Brownian motion and are usually exhaled, particles > 5 μm deposit in the oral cavity and upper respiratory tract, while particles of MMAD between 1-5 μm deposit in the deep alveoli by sedimentation.
Besides the sustained drug release, the use of biodegradable polymeric nanoparticles (NPs) enhance solubility & dissolution rate of
Summary
109
poorly soluble drugs, ensure uniform drug distribution within the lung with an improved cellular uptake in pulmonary and fungal cells
The main goal of this work was to encapsulate MN in biodegradable PLGA NPs, convert them into NCMs by spray drying to optimize their size for delivery to the deep alveoli and confirm their re-dispersion into NPs as soon as they come in contact with the lung lining fluid. Accordingly, the work in this thesis was divided into three chapters:
Chapter I: Preparation and characterization of optimized MN containing PLGA NPs
First, MN NPs were prepared by emulsion solvent evaporation method using PLGA. The effect of different fabrication variables such as homogenization time (2 or 3 minutes), PVA concentrations (from 0.25 to 1%), drug amounts (10, 30 and 40 mg) and aqueous phase volume (40, 60 and 80mL) was investigated. The prepared NPs were evaluated according to their entrapment efficiency (EE%), drug loading (DL%) and particle size. The formula showing highest EE% and DL% was further optimized using a full factorial design experiment where the polymer types (PLGA 75:25 and PLGA 50:50), polymer amounts (100, 200, 300mg) and organic to aqueous phase volume ratio (PVR) were the factors under study. For characterization, the prepared NPs were morphologically examined and the analysis of the factorial design, done by expert software program, showed the effect of these variables on NPs encapsulation efficiency (EE%), drug loading (DL%) and particle size. from the results obtained, it was found that:
1) The use of 30 mg drug, 80 ml aqueous phase, 1% PVA and homogenization for 3 minutes was optimum for MN NPs preparation by solvent evaporation technique
Summary
110
2) The factorial design experiment proved the following:
For EE%
PLGA 75:25 gave higher EE% than the corresponding formulae prepared using PLGA 50:50.
Amount of PLGA: 300 mg gave the highest EE% (49.58%).
PVR of 1:2 ratio was needed for better EE%.
For DL%:
PLGA 75:25 gave NPs with a higher DL% than PLGA 50:50.
The highest DL% of 9.98% was obtained with 100 mg polymer.
PVR of 1:2 gave higher DL% than the corresponding formulae prepared using 1:4 ratio.
For particle size:
PLGA 75:25 gave NPs with higher particle size than PLGA 50:50.
Particle size decreases as the amount of PLGA used increases.
A 1:2 PVR gave NP with larger particle size than 1:4 ratio.
F10 prepared using 100 mg PLGA 75:25 with PVR of 1:2 gave MN NPs with 36.96% EE and optimum DL% of 9.98%, It has a particle size of 341.9 nm and zeta potential of -9.06 mv.
Chapter II: Preparation and characterization of MN nanocomposite microparticles by spray drying
In this chapter, the best formula prepared in chapter I was spray dried to obtain nanocomposite microparticles (NCMs).The conditions of spray drying were firstly optimized, by varying the inlet temperature and feed concentration between 45 and 67°C and 0.5 and 1%,
Summary
111
respectively. The prepared MPs were evaluated according to the yield %, powder flowability (angle of repose) and powder re-dispersibilty. A factorial design experiment was then adopted for studying the effect of adding mannitol or leucine carriers to the NP at 3 different levels(0, 25 and 50mg) on formed MPs.The parameters investigated were yield%, powder flowability, redispersibilty, MMAD and moisture content. The MPs were also evaluated for their particle morphology, differential scanning calorimetry (DSC), x- ray diffraction (XRPD), in vitro drug release and aerodynamic deposition.
from the results obtained, it was found that:
1) An inlet temperature of 45oC and 0.5% feed solution concentration was optimum for spray drying the prepared NPs.
2) The following results were obtained based on the factorial design experiment:
a) The amount of carriers did not affect the tested properties.
b) The inclusion of leucine either alone or combined with mannitol increased the yield% of the spray dried powders more than mannitol.
c) Mannitol alone improved powder flowability more than leucine and its mixture.
d) Powder re-dispersibility was improved in all formulae containing leucine.
e) The MMAD was not affected by either mannitol or leucine either alone or combined.
f) The moisture content was within the accepted limits in all formulae disregarding their composition.
Summary
112
Besides, the other characterization done showed the following:
a) SEM images of leucine containing particles showed corrugated surface, while those of mannitol containing particles were smooth and fused.
b) DSC thermograms showed the entrapment of the drug within the polymer matrix in an amorphous form.
c) XRPD pattern showed that spray drying conditions were able to maintain the drug in an amorphous form.
d) When the Twin Stage Impinger (TSI) was used to determine the in vitro aerosolization properties, S7 revealed the best characteristics with FPF (69%) and ED (82%).
e) In-vitro release studies showed a biphasic release pattern in all MPs and in the NPs with a delayed release in S7.
3) S7 containing leucine only, was found to be the best formula with Sf/Si (1.02), ED% (82%) and FPF (69%).
Chapter III: Evaluation of the antifungal activity and cytotoxicity of MN nanocomposite microparticles
NCMs showed an eight fold higher antifungal activity and lower MIC against candida albicans compared to MN and were found to be in the safety margin when used in the antifungal concentration with human lung epithelial cells.