الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Osteoarthritis (OA), a serious disease, affects whole joint tissues resulting in
structural changes in cartilage, synovial inflammation and bone remodeling.
Management of OA primary focuses on pain reduction and function restoration using anti-inflammatory and analgesic agents to relief symptoms only but they can’t retard deterioration and structural alterations of OA.
Therefore, disease-modifying OA drugs (DMOADs) were investigated based on good understanding of key factors contributed to OA pathogenesis to retard joint degeneration for repairing the existing joint damage.
However, a lot of challenges facing DMOAs resulted in an unmet clinical need for OA modifying therapeutics such as associated side effects and low poor bioavailability. Diacerein, a prodrug converted to rhein (RH) prior to its systemic absorption showing its promising chondroprotective effect.
Unfortunately, low oral
bioavailability and substantial side effect (diarrhea) limited its effective OA therapy.
Therefore, delivery of such promising agents through efficient drug delivery systems
might be a meaningful step towards OA therapy.
Intra-articular (IA) drug delivery
represents many benefits given the localized nature of OA offering high drug
concentration while minimizing substantial side effects associated to systemic one.
While rapid clearance following IA administration fenestrated these benefits.
<To< optimize the IA route, several strategies were developed regarding increasing the joint<>residence time. Recently, nanocarriers attracted a significant attention in this regard.
<The present thesis aimed at developing and evaluating suitable drug delivery systems
for local administration of rhein (RH), active metabolite of diacerein, with the aim of
improving therapeutic efficacy, reduced side effects and targeted the diseased tissue
with cartilage homing agents like chondroitin sulfate and phospholipids to overcome
disadvantages associated with conventional preparations.
<The work in this thesis is divided into two parts:
Part I: Development and evaluation of targeted Intra-Articular
Rhein solid lipid nanoparticles for Arthritis therapy>
The objective of this part was development of intra-articular formulations containing
rhein loaded solid lipid nanoparticles (RH-SLNs) for localizing the active drug form
in the joint tissues based on two different approaches to act as local slow-release drug
depots, allowing long intervals between administrations.
Different RH-SLNs formulations were prepared for this purpose based on
hydrophobic ion pairing (HIP) complex formation using stearylamine (SA) as anionic
lipophilic counterion at different molar ratios in order to achieve acceptable drug
loading, sustained drug release and high positively charged surface for passive
targeting to high negatively charged glucosaminoglycans side chains of cartilage
extracellular matrix converting cartilage ECM from drug barrier to drug reservoir.
<Moreover, excess deposited stearylamine on particles surface allow functionalization
of RH-SLNs surface with chondroitin sulfate (CHS) as a ligand for cartilage active
targeting and for synergistic therapy owing to its nature and activities.
<CHS was
added in different concentrations to impart good surface charge reversal. Firstly the
developed HIP complexes were evaluated by FTIR, DSC, n-octanol solubility,
partition coefficient determination.
Afterwards, the prepared SLNs were evaluated by
determining their size, PDI, surface charge, FTIR, DSC, morphology, in-vitro drug
release and storage stability.
Thereafter, selected formulations were subjected to invivo evaluation by determining drug residence time into cartilage and evaluating invivo efficacy on OA rat model through histological, toxicological and biochemical
assessment.
Results obtained showed that: RH-HIP complexes were prepared using solvent evaporation method and
confirmed by FTIR, DSC resulting in lipophilicity enhancement especially at
higher SA concentration (RH-HIP 1:3).
< RH-HIP complexes improved RH loading
and entrapment efficiency into the prepared RH–SLNs.
<selected passive targeted RH-SLNs formulation F5 containing (10mg RH, 30mg
SA, 500mg compritol ATO 888 as lipid matrix and 300mg poloxamer F127 as
stabilizer) showed particle size 142.5 ± 1.47 nm, narrow PDI (0.249 ± 0.01), high
positively charged surface (41.8 ± 5.6 mV) and high EE% (100%) concomitant to
sustained release profile where 70% of RH total amount was released over 13 days.
Active targeted formulations were prepared by addition of serial concentrations of
CHS to F5 dispersion in an attempt to functionalize SLNs surface. selected active
targeted CHS-RH-SLNs formulation F9 containing (25mg CHS, 10mg RH, 30mg
SA, 500mg compritol ATO 888 and 300mg poloxamer F127) showed acceptable
results regarding surface charge reversal (-28.3 ± 2.07 mV), particle size (156.8 ± 0.05 nm), PDI (0.268± 0.006), EE% (95.8±0.2 %) without affecting RH release
profile compared to uncoated one (F5).
<Storage of F9 in refrigerator over 3 months showed non-significant change in
particle size, PDI, ZP and EE%. Similarly, F5 showed non-significant change in
particle size, PDI and EE% but significant decrease in ZP was observed on storage
over 3 months. selected formulations F5, F9 were subjected to further in-vivo studies.
<Both CHS-RH-SLNs (F9) and positively charged RH-SLNs (F5) formulations
showed ability to diffuse through the cartilage ECM and prolonged residence time
in proximity to chondrocytes over 3 weeks.
Passive targeted positively charged F5 and active targeted F9 exhibited
significantly improvement in a monoiodoacetate arthritis rat model. Meanwhile, F9(CHS-RH-SLNs) showed superior efficacy regarding to cartilage and synovium
histological assessment and biochemical analysis as well.
<F9 effectively inhibited inflammatory cytokine (IL-1β), degradation enzyme
(MMP-3) and oxidative markers (MDA and NO) that implicated in OA
pathophysiology, in addition to significantly elevation in agreecan expression
confirming cartilage matrix biosynthesis.
<Finally, both targeting approaches significantly improved OA repair compared to
RH suspension showing a superior efficacy for articular cartilage targeting with
CHS to achieve a great potential on OA therapy.
Part II: Flexible phytosomes as novel delivery systems for transdermal delivery of Rhein for Arthritis therapy
Topical administration can be a practical alternative to oral delivery of RH to obtain
high local drug concentration into the affected joint overcoming lower oral
bioavailability and reducing risk of systemic side effects.
<Given phospholipids mainly phosphatidylcholines (PCs) possess an integral role in
articular cartilage lubrication in healthy joints while it was depleted in degenerated
joints affected by OA.
<This part focused on developing non-invasive phospholipid
carrier being capable of squeezing to pass intact through intercellular spaces of skin
and synovial membrane for potential synergistic therapy of OA.
Rhein phytosomes (RH-PHY) were developed as advanced drug delivery systems to
improve RH physicochemical properties. Therefore, different preparation methods,different solvents, different temperatures and different phospholipids (SPC) molar
ratios were investigated.
The developed formulations were characterized by DSC, Xray powder diffraction and IR, solubility assessment.
Thereafter, selected RH-PHY was modified with different edge activators to increase
phytosomes deformability and subsequently enhance RH transdermal penetration.
As were Tween 80 (TW80), Span 80 (SP80) and Sodium deoxycholate (SDC).
Each
EA was incorporated in four weight ratios using 5, 10, 15 and 20% with respect to the
phospholipid (SPC).
The formulations were evaluated concerning particle size, zeta
potential, PDI, EE%, flexibility, surface morphology, in-vitro drug release and ex-vivo
skin permeation