الفهرس 
general introduction
induction of the solid tumorsOnly 14 pages are availabe for public view
 |  | from | 210 |  |  |
| | | from | 210 | | |
Abstract
The transdermal pathway appears to be one of the most promising drug delivery
routes due to the merits it carries over other routes as it allows for the controlled
and constant delivery of molecules especially in chronic diseases, avoiding firstpass
effect and non-invasive application.
Targeting solid tumors via the transdermal route has risen as an encouraging
emerging approach. Though, the skin poses exceptional barrier properties, which
challenge the delivery of all the therapeutic agents, generally and the lipophilic
molecules, specifically, due to the high probability of their confinement and
entrapment in the skin lipid layers. In transdermal delivery, the goal of dosage
design is to maximize the flux through the skin into systemic circulation.
Accordingly, various strategies have been implemented to augment the transdermal
delivery of bioactives. Mainly, they include in one hand methods that act on the
molecule or the barrier itself such as: iontophoresis, electroporation, sonophoresis
and on the other hand, there are other methods that depend on formulation
adjustment such as: the use of colloidal carriers like microemulsions, lipid-based
nanoparticles and vesicular systems
Microemulsions are nano-colloidal systems systems composed of oily and aqueous
phases, together with surfactants and co-surfactants. Hydrophobic drugs that can
be integrated (solubilized) in the oily phase and water phase hydrates the skin
leading to increased permeability. The surfactants and co-surfactants act as
penetration enhancers and can impact the skin barrier functions in many aspects.
Microemulsions are isotropic, macroscopically homogeneous, kinetically
thermodynamically stable, translucent and with low energy input method of
preparation. On a microscopic level the surfactant molecules form an interfacial
Summary
138
film separating the polar and the non-polar domains. This interfacial layer forms
different microstructures ranging from droplets of oil dispersed in a continuous
water phase (O/W-microemulsion) over a bicontinuous “sponge” phase to water
droplets dispersed in a continuous oil phase (W/O microemulsion). The use of
microemulsion as delivery systems can improve the efficacy of a drug, allowing
the total dose to be reduced and thus minimizing side effects.
Thereby, these systems were utilized in this study for the delivery of a
phytochemical, namely Methyl Dihydrojasmonate (MDHJ).
Methyl Dihydrojasmonte (MDHJ) is an oily derivative of jasmonates (which are a
class of plant stress hormones) that is isolated from Jasmine plant (Jasminum
officinale). In plant cells, upon wounding or during a pathogenic attack, methyl
jasmonates (MJ) causes the induction and the accumulation of proteinase inhibitor
as a response. They are also involved in the coordinated activation of programmed
cell death (which resembles mammalian apoptosis) and defence. They were also
reported to attain selective anticancer activities, which were exhibited recently in
both in vitro and in vivo studies. Jasmonates and their derivatives managed to
inhibit the proliferation of cancer cells in vitro and to provoke cell death in
multiple human and murine cancer cell lines such as: breast, prostate, melanoma,
cervix, colon, colorectal, gastric, hepatoma, lung, myeloid leukaemia,
neuroblastoma, sarcoma, lymphoblastic leukaemia and lymphoma cells. They
accomplish selective cytotoxicity against cancer cells even in the presence of
normal cells. Various mechanisms of action are shown by the Jasmonates family to
exhibit the anticancer activities, which include the bio-energetic mechanism, the
re-differentiation mechanism and the reactive oxygen species (ROS)-mediated
mechanism
Summary
139
In this thesis attempts have been made to prepare and characterize novel and stable
MDHJ microemulsion formulations aiming at obtaining optimum transdermal
delivery system possessing high transdermal flux. This is attained via developing a
novel method of specific and accurate analysis of MDHJ and through the
preparation of different MDHJ microemulsion formulations. Furthermore, an
experimental design; Simplex Lattice Mixture Design was used to select the best
MDHJ formulation for transdermal delivery. The evaluation of the microemulsion
formulations was performed using different methods such as: the measurement of
particle size and poly dispersity indices, Transmission Electron Microscopy (TEM)
imaging, ex-vivo permeation studies and cytotoxicity studies. Additionally, further
in-vivo investigations were conducted to investigate the effect the optimum
formulation via application on mice bearing Ehrlich ascites carcinoma (EAC) in
solid form, with auxiliary histopathological examinations to the obtained samples
from EAC mice model.
The work in this thesis is divided into two chapters
Chapter I: Development, optimization and ex vivo evaluation of Methyl
Dihydrojasmonate microemulsion formulations.
This chapter deals with the preparation of microemulsion formulations.
Accordingly, pseudoternary phase diagrams were constructed using several
combinations of oils, surfactants and co-surfactants and following the water
titration method. The drug (MDHJ) was integrated in the oily phase either alone or
in combination with other oils such as Oleic acid, Capryol 90®, isopropyl myristate
(IPM), Labrafac PG®, Labrafac CC® and Labrafil M® in ratio 1:1. Also, Labrasol®,
Summary
140
Transcutol P®, Tween 80® and Plurol Oleique® were employed as surfactants or
co-surfactants. The mixing ratio of surfactant with cosurfactant was kept at 1:1.
Nine systems were constructed and evaluated according to the largest domains of
microemulsion.
Two systems were selected and an experimental design(Simplex Lattice Mixture
Design) was utilized to select twenty six formulations for further investigation
using different weight percentages of oily phase, surfactant /cosurfactant and water
as independent factors, while particle sizes and poly dispersity indicesas dependent
(response) variable.
Seven formulae were chosen for an ex-vivo permeation study through mouse skin.
The best microemulsion formulae from each ME system were selected to be
examined using TEM. The superlative formulation was further investigated on
MCF-7 breast cancer cell lines.
The work in this chapter comprised the following:
1. Analysis of MDHJ in phosphate buffer solution of pH 7.4 Methanol (70:30,
v/v) using Ultra Performance Liquid chromatography (UPLC).
2. Constructing Pseudo-ternary phase diagrams.
3. Preparation of selected microemulsion formulae according to the Simplex
lattice mixture experimental design.
4. Evaluation of the prepared formulation using particle size and poly
disperisty index
5. Ex-vivo skin permeation of the selected MDHJ microemulsions formulae.
6. Transmission Electron Microscopy (TEM)
7. Cytotoxicity studies
Summary
141
The result of this work revealed the following:
1. The isocratic elution based UPLC method showed sharp chromatograms
with a good retention time of 1.6 ± 0.3 min using a mobile phase consisting
of acetonitrile: triethylamine buffer (3 ml/L, pH 2.6) with a ratio of 70:30
v/v; a flow-rate of 0.5 ml/min and an injection volume of 10 μl and utilizing
a detection wavelength of 190 nm. And according to ICH validation
parameters, the UPLC assay method was proven to be highly sensitive and
selective for the investigated drug; MDHJ.
2. Two systems S8 ((MDHJ :Capryol 90®)/ (Labrasol® : Transcutol®)/ water
system) and S9 ((MDHJ: Oleic acid)/ (Labrasol®: Transcutol®)/ water
system) were denoted as successful pertaining to their large microemulsion
domains in the pseudo ternary phase diagram.
3. The data of S8 (MDHJ :Capryol 90®)/ (Labrasol® : Transcutol®)/ water
system) formulations showed that the particle sizes ranged from 10 nm to
440 nm.
4. The data of S8 (MDHJ : Capryol 90®)/ (Labrasol® : Transcutol®)/ water
system) formulations showed polydispersity indices ranging from 0.144 to
0.641 except for FC6,FC12 and FC13 which had a relatively high PDI value
of 1.
5. The data obtained from system S9 ((MDHJ: Oleic acid)/ (Labrasol®:
Transcutol®)/ water system) showed that the particle sizes ranged from 11
nm to 240 nm