الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
Ketoprofen (KP) and tenoxicam (TNX) that assorted as a BCS class II
drug (poor solubility and high permeability) are a potent non steroidal antiinflammatory
drugs (NSAIDs) and used orally to lessen the signs of
rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis.
Administration of these drugs orally is very effective, but clinically they are
commonly restricted because of thier possible adverse effects such as
ulceration of gastrointestinal mucosa, bleeding, or other less common effects
such as a functional renal failure, risk of arterial thrombotic events, and other
hypersensitivities. One of an alternative way of drug delivery, which could
diminish the opportunities of the drug related gastrointestinal and systemic
effects is to administer the drug through the skin. The ability of NSAIDs to
penetrate the skin is impeded by the barrier features of the stratum corneum.
Solid lipid nanoparticles (SLNs) have attracted increasing attention as
dermatological formulation for the delivery of drug molecule due to it is a
small size, controlled release properties, biocompatibility and potentiality
incorporate lipophilic and hydrophilic drugs. They are colloidal carrier
systems consisted of physiological and appropriate lipids with a high melting
point as the solid core, which is overlaid by nontoxic emulsifiers as the outer
shell. One of the disadvantages of SLNs dispersion is the low viscosity for
dermal administration. They must be incorporated into gel to assist
application and to lengthen residence time on the skin.
The aim of our work was to develop ketoprofen and tenoxicam loaded
solid lipid nanoparticles then incorporating the optimized formulations in a
gel administered via transdermal route to avoid their potential adverse effects.
Hence, improving their bioavailability, therapeutic efficiency and patient
compliance.
Abstract
The work in this thesis is divided into two chapters:
Chapter I: Formulation and evaluation of solid lipid nanoparticles based
nanogel for dermal delivery of ketoprofen.
Chapter II: Formulation and evaluation of solid lipid nanoparticles based
nanogel for dermal delivery of tenoxicam.
Chapter I
Formulation and evaluation of solid lipid nanoparticles based nanogel
for dermal delivery of ketoprofen.
The work in this chapter include; (a) Development and optimiziation of
ketoprofen solid lipid nanoparticles through Artificial Neural Network
(ANN) and clustered bootstrap resampling; (b) Formulation of plain gel
matrices of carbopol and incorporate KP loaded SLNs in these matrices; (c)
Evaluating the produced gel formula and comparing it with commercial gel
( Profenid® gel); and (d) Demonstration of a pharmacodynamic model based
approach to compare anti-inflammatory activity of both prepared KP-SLN
gel and commercial gel (profenid®) and test their effectiveness through
performing Carrageenan-induced rat paw edema model.
Preformulation studies were carried out to detect interaction between
ketoprofen, components of solid lipid nanoparticles and carbopol polymer
using differential scanning calorimetry (DSC) and Fourier-transform
infrared spectroscopy (FT-IR).
Artificial neural network (ANN) is a flexible tool that mimics human
brain through passing and processing signals across layers of neurons
interconnected by synapses. Hence, ANN is well-suited for approximating
complex, non-linear relationships between multiple causal and response
variables. Combined with factorial designs that allow investigating several
formulation factors simultaneously in a limited number of experiments.
When it comes to optimization based on non-linear models, assessing
reliability of optimal solutions is important. Although tremendous number of
Abstract
studies use ANN for optimization of drug delivery systems, extremely rare
studies that actually try to evaluate the robustness of their non-linear
optimization. The term ―robustness‖ here describes the ability of the model
to replicate the optimal solution, irrespective of prior assumptions.
Resampling techniques, such as bootstrapping, can test the robustness of
optimization results. The basic idea of bootstrap is random sampling of the
original dataset with replacement to generate arbitrary number of subsets
belonging to the empirical distribution of the original data. Bootstrap
resampling offers a non-parametric technique to estimate confidence
intervals, bias, and variance of a given estimator.
Based on a preliminary study, glyceryl palmitostearate (GPS) was
selected as the lipid, Tween 80 as the surfactant, and soybean lecithin as the
phospholipid for preparing the SLN loaded with KP. The influence of lipidto-
drug ratio (X1), concentration of Tween 80 (X2), and concentration of
lecithin (X3) on particle size (Y1), entrapment efficiency (Y2), and
cumulative amount of drug permeated through excised rat skin in 24 hours
(Y3) was studied using a Box-Behnken design with four center points.
Ketoprofen solid lipid nanoparticles were prepared according to
emulsion/solvent evaporation method. The prepared formulations were
characterized with respect to particle size measurement, EE% and
cumulative amount of drug permeated through excised rat skin in 24 hours.
Then the ANN is trained using measured responses. And finally Clustered
bootstrapping (CBS) was deployed to estimate the uncertainty associated
with the simultaneous optimal solution provided by the ANN model using
the original data.
The morphology of optimized KP-SLN formulation was exmained by
TEM and the stability testing of optimized formula was carried out by
measuring both the average encapsulation efficiency and the particle size
monthly for a period of three months.
Abstract
The optimized KP-SLN dispersion were incorporeted in hydrogel using
carbopol 974 NF and The prepared gel was evaluated for it is physical
properties by visual inspection of clarity, homogeneity, spreadability,
rheological properties. In vitro drug release and ex-vivo permeability of KP
released from KP-SLN gel were also performed.
The skin irritation potential of the KP-SLN gel was evaluated by acute
skin irritation test. The study design used for evaluating the antiinflammatory
equivalence of the KP-SLN gel and the commercial
formulation (profenid® gel) was based on the 1995 FDA guidelines for
assessing bioequivalence of topical dermatological corticosteroids.
Carrageenan-induced rat paw edema model was used to evaluate the Antiinflammatory
activity. Eighteen female Wistar rats (weight 180–200 g) were
assigned to 6 groups of three. Combinations of treatments (test and
reference) and dose durations (0.5, 2, and 6 hours) were randomly assigned
to the animal groups.
The results revealed that:
The DSC and FT-IR studies revealed that KP was found to be
compatible with SLNs and gel components.
Lipid-to-drug ratio of 7.85 [bootstrap 95%CI: 7.63–8.51], Tween 80 of
1.27% [bootstrap 95%CI: 0.601–2.40%], and Lecithin of 0.263%
[bootstrap 95%CI: 0.263–0.328%] were predicted to produce optimal
characteristics.
ANN coupled with clustered bootstrap is a useful method for finding
optimal solutions and estimating uncertainty associated with these
solutions.
TEM revealed that KP-SLN had a spherical shape with thin layer
surrounding the particles which postulated a drug-enriched core model.
The optimized formula was found to be stable on storage for a period
of three months.
Abstract
KP-SLN gel was elegant and opaque, No lumps or air bubbles were
observed and it has good homogeneity and better spreadability.
It was found that KP-SLN gel has better flow behavior and rheological
prosperities than commercial one. The degree of thixotropy increased
in case of KP-SLN gel compared with commercial gel. KP-SLN gel
exhibited the highest area of hysteresis loop and highest Farrow’s
constant.
The release rate of KP from SLNs was lower than the corresponding
commercial one, suggesting the ability of the SLNs to retard the release
of KP.
The profiles of KP permeability through excised rat suggest that SLNs
are efficient permeation enhancers, where KP permeation rate is higher
when incorporated in the SLNs-gel formulation compared with the
commercial gel.
Application of the KP-SLN gel to rabbit skin was not associated with
irritation, erythema or edema.
Parameters Smax (maximum change in edema thickness from baseline)
and T50 (the time at which 50% of the maximum change is reached)
were significantly larger in the KP-SLN gel, while SD50 (the dose
duration producing half-maximal change) was basically the same.
While exhibiting similar potencies (equal SD50 values), our optimized
SLNs formulation is more efficacious than the commercial formulation
(larger Smax value) and produces more delayed response (larger T50
value). This result is understandable in the light of the fact that KP
loaded in the SLNs was released at slower rate, but penetrated the skin
at higher rate.
SLNs improve the efficacy of topically applied KP and retard the
response to it. In vivo activity assessment using pharmacodynamic
modeling allows mechanistic understanding of comparative
Abstract
performances of different formulations, and helps design efficient
bioequivalence methods that are sensitive to potential variations in drug
delivery systems.
Chapter II
Formulation and evaluation of solid lipid nanoparticles based nanogel
for dermal delivery of tenoxicam
This chapter included preparation of tenoxicam loaded SLNs by
emulsion/solvent evaporation method. Furthermore, the influence of some
formulation variables on the characteristics of the developed SLNs was also
investigated.
Preformulation studies were carried out to detect interaction between
tenoxicam and components of SLNs using differential scanning calorimetry
(DSC).
Eight formulations were proposed adopting a factorial design (23), in
which three factors were tested. They were namely, lipid type (Compritol or
Precirol), surfactant concentration (1 and 2% (w/v) poloxamer 188) and cosurfactant
concentration (0.25 and 0.5% (w/v) lecithin). SLNs were prepared
using a modified emulsion/solvent evaporation method. An amount of 10 mg
tenoxicam was used in each formulation.
The prepared formulations were characterized with respect to EE%,
particle size measurement by dynamic light scattering (DLS), in vitro release,
ex vivo permeation and stability studies.
Stability testing was carried out on formulation S8 (containing precirol as
a solid lipid material, 0.5% (w/v) lecithin and 2% (w/v) poloxamer 188) by
measuring particle size and EE% monthly for a period of three months.
The selected formula of TNX-SLN (S8) as well as plain TNX were
incorporated into carbopol 974 NF polymer to form the gel (KP-SLN gel).
And finally the anti-inflammatory activity of the TNX-SLN gel was evaluated
using carrageenan induced rat paw edema model.
Abstract
The results revealed that:
The results of DSC obtained showed no interaction between tenoxicam
and components of SLNs.
Tenoxicam was successfully embedded in SLNs’ core with high EE%
reached 89.76%. SLN formulations containing compritol (S1–S4)
showed a significant higher EE% (p<0.05) compared to those
containing precirol (S5–S8). Also, increasing the concentration of
surfactant from 1 to 2% (w/v) resulted in a significant decrease in the
EE% of the produced SLNs (p<0.05). On the other hand, increasing
lecithin concentration resulted in a consequent increase in EE% (p <
0.05). The combination of Compritol with 1% (w/v) poloxamer 188 and
0.5% (w/v) lecithin, S3, gave the highest EE% while the combination
of Precirol with 2% (w/v) poloxamer 188 and 0.25% (w/v) lecithin, S6,
gave the lowest EE%
All the prepared SLNs exhibited small particle size ranging from 58 to
386 nm. Formulations containing Compritol showed larger particle
sizes than those containing Precirol and a gradual decrease in particle
size was observed with increasing surfactant concentration (p < 0.05).
Also, the particle size was found to decrease with increasing lecithin
concentration (p < 0.05). The combination of Precirol with 2% (w/v)
poloxamer 188 and 0.5% (w/v) lecithin, S8, gave the smallest particle
size while the combination of compritol with 1% (w/v) poloxamer 188
and 0.25% (w/v) lecithin, S1, gave the largest particle size.
Tenoxicam loaded-SLN formulations were able to retard its release and
the percentage of tenoxicam released up to 8 hr ranged from 36.31% to
59.51%. Higher release was achieved with Precirol (S5–S8) compared
to Compritol (S1–S4). Increasing the poloxamer 188 concentration led
to corresponding increase in the percentage of tenoxicam released.
Abstract
Also, increasing lecithin concentration resulted in an increase in the
percentage of tenoxicam released. Formulation S8 exhibited the highest
percentage of tenoxicam release.
The release pattern of the drug from all SLNs formulations and TNX
solution followed first-order kinetics.
Formulation S8 was found to be stable on storage for a period of three
months, so it was chosen to be incorporated into hydrogel matrices for
further study.
It was found that gel formula containing TNX-SLN has better flow
behavior and rheological prosperities than plain one. The degree of
thixotropy increased in case of TNX-SLN compared with plain TNX.
TNX-SLN Formula exhibited the highest area of hysteresis loop and
highest Farrow’s constant.
TNX-SLN gel showed 80.9% inhibition of the rat paw edema which
was significantly higher than the plain TNX gel (45.9%) at p<0.05.
This suggests improved anti-inflammatory activity of TNX when
incorporated into a solid lipid nanoparticles.