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Original Article
Iranian Journal of Pharmaceutical Sciences
2023: 19 (3): 194- 207
https://journals.sbmu.ac.ir/IJPS
Design Hybrid Nanogel of Prednisolone for Topical Application,
Preparation, Characterization, In-vitro and Ex-vivo Evaluation
Hayder Kadhim Draisa
a Al-Mustaqbal University, College of Pharmacy, Babil, Iraq.
Abstract
The prednisolone was very slightly soluble in water. It was a curative agent against oral recurrent aphthous
stomatitis. The main objective of this study is to design, prepare, and evaluate a hybrid nanogel of prednisolone
as a topical dosage form to increase prednisolone solubility, stability, and therapeutic activity. The microwave-
based method prepared nine prednisolone lipid polymer hybrid nanocarriers LPHNs formulations (H1-H9). The
conventional prednisolone gel (G) was prepared by solvent diffusion. The H1-H9 was evaluated
thermodynamically and entered into characterization processes. The hybrid nanogels HN1-HN9 formulations
were tested for various evaluations. All the H1-H9 formulations showed high thermodynamic stability and
nanosized globules, low polydispersity index, acceptable surface charge, entrapment efficiency, and drug loading.
The evaluation processes indicate stable organoleptic properties, high homogeneity, fair pH and spreadability
coefficient values with plastic viscosity and no erythemic reaction. The profile of prednisolone release and
permeability coefficient (cm/min) was significantly higher (p-value <0.05) for HN3 and significantly lower (p-
value < 0.05) for conventional prednisolone gel (G). The optimized HN1-HN9 formulations were promised drug
delivery systems for treating recurrent aphthous stomatitis and a wide variety of oral lesions in addition to local
and transdermal delivery of various therapeutic agents and cosmetics.
Keywords: Recurrent aphthous stomatitis; Microwave-based method; Prednisolone; Chitosan; Cardamom oil; Topical
pharmaceutical dosage form.
1. Introduction
With the wide spread of diseases and epidemics
in our time, it has become imperative for
researchers and industrial pharmacologists to
find the necessary drug designs to limit the
spread of many diseases that may affect the
quality of human life and everyday life. The
oral lesion is one of the important diseases
related to human comfort and permanence of
productivity. Recurrent aphthous stomatitis
(canker) is the most famous among differential
diagnoses of oral lesions. It is chronic mucosal
layer inflammation of the mouth. The patient
shows a painful burn sensation in the affected
Corresponding Author: Dr. Hayder Kadhim Drais, Al-
Mustaqbal University, College of Pharmacy, Babil, Iraq.
E-mail: deera2020@gmail.com
Cite this article as: Drais KH, Design Hybrid Nanogel of
Prednisolone for Topical Application, Preparation,
Characterization, In-vitro and Ex-vivo Evaluation, Iran. J.
Pharm. Sci., 2023, 19 (3): 194- 207.
DOI: https://doi.org/ 10.22037/ijps.v19i3.42239
Hybrid Nanogel of Prednisolone
195
part of the mouth that can develop into an ulcer
within 2 to 48 hours [1].
The oral aphthae etiology may include local
trauma, smoking cessation, genetic factors,
food allergens, endocrine alterations such as
the menstrual cycle), specific microbial agents
and chemical products, stress, and anxiety [2].
Several approaches to canker treatment
include pain alleviation, accelerated healing of
ulcers, and inhibition of aggravation [3]. These
can be achieved by inhibition of inflammatory
processes. Topical corticosteroids greatly
limited the inflammatory responses associated
with canker development. The role of
glucocorticoids in oral lesion control was vital
because they acted as potent anti-
inflammatory actions, analgesic, and
immunomodulators, including the decrease in
the number and function of different immune
cells, such as eosinophils, T and B
lymphocytes, monocytes, neutrophils and
decrease the production of chemokines,
cytokines and eicosanoids and promote the
inhibitory factor production of macrophage
migration at sites of inflammation which can
control canker and contribute to the speedy
recovery process [4, 5].
Prednisolone is a potent synthetic
glucocorticosteroid highly employed for its anti-
inflammatory and immunosuppressive attributes.
It was belonging to class II according to the
biopharmaceutical classification system. It is a
hydrophobic therapeutic agent and is slightly
soluble in water. The solubility factor of drugs is
an important pillar in the pharmaceutical
manufacturing process [6, 7].
The topical pharmaceutical dosage forms
such as nanogels represent the first choice for
canker treatment because they are effective,
safe, and provide high local drug concentration.
Nanogels are efficient nanocarriers that have
three-dimensional cross-linked network
chassis. It has suitable bioadhesive and
biocompatible attributes. The main obstacles of
nanogels are hydrophilicity and poor control of
drug release that restrict the delivery of
hydrophobic therapeutic agents [8-10]. A more
recent delivery system, hybrid nanogels (HNs),
has emerged to overcome this demerit. The
HNs is a drug delivery system that protects the
encapsulated hydrophilic and hydrophobic
drugs. The main constituents of HNs are lipid-
based nanoparticles, polymer, and gel bases that
give combined features of polymeric
nanocarriers and lipid-based nanocarriers [11-
13]. The lipid enhances solubility and increases
entrapment efficiency of hydrophobic drugs,
whereas the polymer provides great control to
therapeutic agent release, compared to lipid
base nanocarriers and polymeric nanoparticles
alone [14]. Hybridizing polymeric and lipid-
based nanoparticles provides a drug delivery
system that gives nanoscale particle size,
furiousness, higher drug payload, sustained
drug delivery, and high stability during
formulation storage [15, 16]. The present
research aims to prepare and characterize
prednisolone hybrid nanogel (HN) to increase
the solubility and permeability of prednisolone
and sustain drug release that leads to increased
local bioavailability and effectiveness.
2. Materials and Methods
2.1. Materials
Prednisolone, chitosan, and triethanolamine were
purchased from Beijing Yibai Biotechnology Co.,
Ltd. (China). Polyacrylic acid (PAA)-940,
Drais KH / IJPS 2023; 19 (3): 194- 207
196
polyethylene glycol (PEG)-laurate, and lauric
acid were purchased from Nanjing Duly Biotech
Co., Ltd. (China). Hemani International KEPZ
(Karachi, Pakistan) purchased the coconut and
cardamom oil. The ethanol, methanol, potassium
chloride, disodium hydrogen phosphate, sodium
hydroxide, and potassium dihydrogen phosphate
were purchased from Grin Land Chemical
Company (United Kingdom). All solvents and
reagents used in the experiments were of
analytical grade.
2.2. Methods
2.2.1. Preparation of prednisolone LPHN
formulations (H1-H9)
The microwave-based method prepared nine
prednisolone LPHN formulations (H1-H9). The
first step was preparing a hydrophobic blend by
dissolving prednisolone, chitosan polymer, and
lauric acid in cardamom oil and coconut oil using
a magnetic stirrer device at 1000 rpm for 5
minutes. The second step was a hydrophilic blend
that contained PEG-laurate, and double distilled
water was prepared under a magnetic stirrer at
1000 rpm for 5 minutes. The third step involves
mixing hydrophobic and hydrophilic blends
according to the optimized concentrations
described in Table 1. The mixture was inserted in
a microwave instrument, Denka YMO-G30LR-
30L model, for less than 10 seconds, then
subjected to a magnetic stirring of 1000 rpm to
form a colloidal dispersion system of
prednisolone LPHN [13,15].
2.2.2. Preparation of prednisolone hybrid
nanogel formulations (HN1-HN9)
It was formulated by PAA-940 dissolving in
double distilled water with continuous stirring
using a magnetic stirrer. A few drops of
triethanolamine were added until a pH of about
(6.2-7.4) was obtained. Prednisolone LPHNs
were mixed with newly prepared gel in a 1:1
ratio using an electric homogenizer to get a
homogeneous prednisolone hybrid nanogel
(HN).
Table 1: The selected prednisolone hybrid nanogel formulations (HN1-HN9) for characterization and
optimization.
Formulation
code
Prednisolone
%(w/w)
Cardamom
%(w/w)
Coconut
oil
%(w/w)
Lauric
acid
%(w/w)
Chitosan
%(w/w)
PAA-
940
%(w/w)
PEG-
laurate
%(w/w)
Distilled
water %
(w/w)
Up to
HN1
1
3
1
1
0.5
0.2
30
100
HN2
1
3
1
1
0.5
0.2
34
100
HN3
1
3
1
1
0.5
0.2
38
100
HN4
1
3
1
1
0.5
0.4
36
100
HN5
1
4.5
1.5
1.5
0.5
0.4
36
100
HN6
1
6
2
2
0.5
0.4
36
100
HN7
1
4.5
1.5
1.5
0.2
0.2
38
100
HN8
1
4.5
1.5
1.5
0.4
0.4
38
100
HN9
1
4.5
1.5
1.5
0.6
0.6
38
100
G
1
--
--
--
--
0.4
--
100
Hybrid Nanogel of Prednisolone
197
The prednisolone hybrid nanogel formulations
(HN1-HN9) were stored in a tightly closed
container at 25 OC temperatures for evaluation
[17- 19]. The conventional gel of prednisolone
(G) was prepared by dissolving 1 gram of the
drug in 5ml of ethanol and then incorporating
to PAA-940 base gel to create prednisolone gel
that was kept in the container open for 24
hours to get gel ready for laboratory work [18].
2.3. Thermodynamic stability tests of
prednisolone LPHNs formulations (H1-H9)
The thermodynamic stability experiments [15]
were achieved to evaluate physical stability as
follows:
2.3.1. Centrifugation test
It was achieved through VS-18000 M, Vision
Scientific Co. LTD-Korea at 5000 rounds per
minute (rpm) for about 30 minutes, and the
physical appearance of prednisolone LPHN
formulations (H1-H9) was checked through a
centrifugation process.
2.3.2. Heating-cooling test
For about 48 hours, prednisolone LPHN
formulations (H1-H9) were stored at 45oC and
0oC temperatures using a refrigerator for each
temperature.
2.3.3. Freezing–thawing test
Under two temperatures of -21oC and 21oC,
prednisolone LPHN formulations (H1-H9) were
tested for physical, not less than 24 hours for
each temperature. The prednisolone LPHN
formulations (H1-H9) with maximum physical
stability were selected for investigation.
2.4. Characterization of the prednisolone
LPHNs (H1-H9)
2.4.1. Particle size determination
Five milliliters of the prednisolone LPHNs (H1-
H9) were sonicated at 37oC for 30 min and
measured using the Horiba instrument, Ltd.
Kyoto, Japan analyzer. Photon correlation
spectroscopy (PCS) was an experimental
technique used to determine the particle size of
prednisolone LPHNs (H1-H9). The experiment
was performed in three trials [14-16].
2.4.2. Polydispersity index (PDI) determination
PDI of the prepared prednisolone LPHNs (H1-
H9) was achieved to determine the distribution
pattern of nanoparticles within the colloidal
system. Samples of five milliliters were
sonicated at 37oC for 30 min and measured using
Horiba Instrument, Ltd. Kyoto, Japan. The PCS
technique had been used in the experiment. The
higher PDI value indicates the lower uniformity
of particle size. The measurement was
performed in three trials [14-16].
2.4.3. Measurement of zeta potential (ZP)
The PCS technique was used to measure ZP.
The ZP is an index that gives us information
about the surface charge of nanoparticles.
Samples of five milliliters were sonicated at
37oC for 30 min and measured using Horiba
Instrument, Ltd. Kyoto, Japan. The experiment
was achieved in three trials [14-16].
2.4.4. Entrapment efficiency (EE) and drug
loading (DL)
The EE expressed in percentage (%) is a
parameter to reveal the therapeutic agents'
Drais KH / IJPS 2023; 19 (3): 194- 207
198
encapsulation process. The indirect method was
achieved to determine EE by calculating the
free prednisolone drug in the super layer after
applying the centrifugation process. Then,
apply the following equation 1:
EE (%) = [(Total prednisolone amount – Free
prednisolone amount / Total prednisolone
amount)] ×100 Equation 1
The drug loading (DL) parameter expressed in
percentage (%) is the prednisolone quantity
found in the nanoparticles divided by the total
quantity of lipids employed. It is determined by
equation 2:
DL (%) = [(Total prednisolone amount − Free
prednisolone amount / Total lipid amount)] ×
100 Equation 2
The experiments were performed in triplicate
for EE and DL [15].
2.5. Evaluation of prednisolone hybrid nanogel
formulations (HN1-HN9)
2.5.1. Organoleptic Test
It is performed by naked eye observations of the
odor's shape, color, and smell that can take
place in prednisolone hybrid nanogel
formulations (HN1-HN9) at 0, 7, 14,21and 28
days. The tests occurred in triplicate [20, 21].
2.5.2. Homogeneity measurement
A homogeneity test is performed by application
of 0.5g of prednisolone hybrid nanogel
formulations (HN1-HN9) to transparent
material such as glass pieces.
2.5.3. Measurement of pH
The pH test is achieved by employing a digital
pH meter of Biobase Meihua Trading Co., Ltd.,
China. The samples were taken from
prednisolone hybrid nanogel formulations
(HN1-HN9) of 10 g. The skin criteria pH is in
the range of 4.5 - 6.5. The measurements were
done in triplicate [20, 21].
2.5.4. Spreadability studies
The spreadability test is one of the important
measures for prednisolone hybrid nanogel
formulations (HN1-HN9). Two separated glass
slides with dimensions (7.5×2.5 cm) performed it.
The first lower slide that contains 0.5 g of (HN1-
HN9) was tied with a wooden base. When the
thread and 100 g weight tied to the second glass
slide were applied to the first slide, the pulling
process to the distance of 7.0 cm was achieved.
The time in seconds and weight in grams that
required moving the second glass slide was
recorded. The spreadability process can be
calculated from the following equation 3:
S=M×L / T Equation 3
S = Spreadability, M = Weight that tide to upper
glass slide, L = Length of glass slide T = T is the
time to separate two glass sides. The study was
achieved in three trials [21].
2.5.5. Viscosity measurement
The viscosity of prednisolone hybrid nanogel
formulations (HN1-HN9) was tested using a
rotational digital rheometer with a spindle
number (2) from Biobase Meihua Trading Co.,
Ltd. at 25°C. The samples of the hybrid nanogel
were exposed to different rotating speeds in
RPM, which are (0.1, 0.3, 0.6, 1.5, 3, 6, 12, 30,
and 60). The experiments were achieved in
three trials [15, 21].
Hybrid Nanogel of Prednisolone
199
2.5.6. In-vitro diffusion studies
The in-vitro diffusion experiments were
achieved using a Franz diffusion cell. The
samples of prednisolone hybrid nanogel
formulations (HN1-HN9) and conventional
prednisolone gel (G) were applied onto the
dialysis membrane surface inserted between
donor and receptor chambers. The phosphate
buffer solution pH 7.4 was 200 mL, filled the
receptor compartment, and treadled constantly
using magnetic beads at 25°C. Samples of 0.1
gram from the receptor compartment were
collected at predetermined time intervals (0,
0.25, 0.3, 1, 2, 4, 6, 8, and 12 h) with the
replacement of the same volume of fresh
diffuse solution to conserve constant volume.
The samples were analyzed using an
ultraviolet-visible spectrophotometer (Biobase
Meihua Trading Co., Ltd) at 243nm [21-23].
2.5.7. Skin irritation test
Before the skin irritation test, approval was
obtained from the Institutional Ethics
Committee in Ali Obais Hospital (approval
number 239-12.1.2023). The fasted male
sheep weighing about 16 kg were used to test
skin irritation. The male sheep were kept on
standard feed and had free access to food and
water. Hair was removed from the skin surface
of sheep and divided into three places of an
area of 4 cm2 (2cm x 2cm) for application of
500 mg samples of prednisolone hybrid
nanogel (HN1-HN9), hybrid nanogel (without
drug) and conventional prednisolone gel (G),
where the application process twice daily. The
testing area was observed for any erythemic or
edema reaction after 1, 24, 48, and 72 h of
sample application. The sensitivity was graded
as 0, 1, 2, and 3 for no reaction, slight patchy
erythema, patchy erythema, and severe
erythema with or without edema, respectively
[21].
2.5.8. Ex-vivo skin permeation study
An ex vivo study was achieved on fasted male
sheep weighing about 16 kg. The animal was
slew and anatomized according to the ethics
committee's approval. The hairless abdominal
skin was surgically isolated, and carefully
removed subcutaneous fat by cold normal
saline solution. The abdominal skin was cut
into segments of 4 cm2 (2cm x 2cm) to be a
biological membrane inserted between the
donor and receptor compartment of a Franz-
type diffusion cell containing 200 mL of
phosphate-buffered saline pH 7.4 in the
receptor chamber. Samples of prednisolone
hybrid nanogel formulations (HN1-HN9) and
conventional prednisolone gel (G) were 0.1
grams and placed in the donor chamber of the
Franz cell. Samples from the receptor chamber
(200 mL) were withdrawn at periodic intervals
and analyzed for the quantity of prednisolone
permeated using an ultraviolet-visible
spectrophotometer (Biobase Meihua Trading
Co., Ltd) at 243 nm. The experiments were
achieved in triplicate. The permeability
coefficients were determined using Equation 4.
M = Peff S Cd tres Equation 4
Where:
M = quantity of therapeutic agent absorbed
Peff = effective membrane permeability (cm/min)
Cd = apparent luminal drug concentration
(initial concentration. or C donor)
tres = residence time of drug in GI lumen.
S = surface area available for absorption [14,15].
Drais KH / IJPS 2023; 19 (3): 194- 207
200
2.6. Statistical analysis
The experimental data was obtained as the
mean of three samples with the application of
standard deviation. Statistical analysis was
achieved by the Microsoft Excel program
2010. The statistical test was an analysis of
variance (ANOVA), where the level (P<0.05)
was kept as not significant [14, 15].
All experiments were performed under the
approval of the ethics committee of scientific
research in Babil Health directorate, Ali Obais
Hospital, where the approval number was 239-
12.1.2023.
3. Results and Discussion
3.1. Formulation of prednisolone lipid-
polymer hybrid nanocarriers LPHN (H1-H9)
and prednisolone hybrid nanogel (HN1-HN9)
The prednisolone LPHN (H1-H9) were prepared
successfully using the microwaves-based method
according to experimental components, as shown
in Table 1. All the formulated LPHNs (H1-H9)
enter the thermodynamic stability analysis to check
the physical stability. It was found that all the
prednisolone LPHN formulations (H1-H9) had a
stable physical constancy where there was no
phase separation with constant appearance and
color that indicate pharmaceutical physical
stability. These prednisolone LPHNs (H1-H9)
formulations were entered into the characterization
processes and used to formulate prednisolone
hybrid nanogel (HN1-HN9).
3.2. Characterization of the prednisolone
LPHNs (H1-H9)
3.2.1. Particle size determination
The study of the average size of prednisolone
LPHNs (H1-H9) formulations was determined
by z-average using the DLS technique. Particle
size is an important parameter affecting
stability, drug release profile, efficiency,
muco-adhesion, cellular uptake, and bio-
distribution [15]. The outcomes of particle size
analysis were H1 (101 nm); H2 (94 nm); H3
(92 nm); H4 (96 nm); H5 (110 nm); H6 (146
nm); H7 (109 nm); H8 (120 nm) and H9 (131
nm) as shown in Table 2. The variance
analysis showed a significant correlation
between particle size and the independent
variables, PEG-laurate, lipid content, and
chitosan at the level (p<0.05).
3.2.2. Polydispersity index (PDI) determination
PDI is a parameter for measuring prednisolone
LPHN (H1-H9) formulations homogeneity. It
is a dimensionless test with values from 0 to 1.
The smaller values show a finer particle
size distribution, narrower and more
homogenous, while the uniformity of the
particle size in the formulation decreases as
the PDI increases. PDI was from (0.317 to
0.505) as shown in Table 2. The result of the
ANOVA indicated a significant correlation
between PDI as a dependent variable and
PEG-laurate, lipid content, and chitosan at
level (P < 0.05).
3.2.3. Measurement of zeta potential (ZP)
The diffuse layer of charges in a shear plane
around nanocarriers was expressed as zeta
potential. It is used as a parameter related to
nanoparticles' physical stability. The outcome of
the mean absolute zeta potential was (18 to 43
mV) as shown in Table 2. There was a
significant relationship (p<0.05) between zeta
potential and independent variables.
Hybrid Nanogel of Prednisolone
201
3.2.4. Entrapment efficiency (EE) and drug
loading (DL)
The entrapment efficiency and drug loading
gave information about the ability of drug
encapsulation for nanocarriers. The outcomes
of EE (w/w %) were H1 (87.3%), H2
(86.67%), H3 (81.66%), H4 (86.8%); H5
(88.37%), H6 (89.13%), H7 (88.2%), H8
(88.4%) and H9 (88.86%) as shown in
Table 2. The results of drug loading (w/w %)
were H1 (19.6%); H2 (25.6%); H3 (26.67%);
H4 (25.3%); H5 (18.03%); H6 (15.03%); H7
(18.6%); H8 (17.8%) and H9 (17.3%) as
shown in Table 2. The clear values of the data
confirm the ability of the prednisolone LPHN
(H1-H9) formulations to accommodate
therapeutic agents. The analysis of variance
confirmed a significant relationship between
dependent variables (entrapment efficiency
and prednisolone loading) and PEG-laurate,
lipid content, and chitosan at level (p<0.05).
Therefore, the null hypothesis was rejected
and accepted the alternative hypothesis.
3.3. Evaluation of prednisolone hybrid
nanogel formulations (HN1-HN9)
3.3.1. Organoleptic Test
It was found that prednisolone hybrid nanogel
formulations (HN1-HN9) show acceptable
physical properties, as shown in Table 3.
Table 3: The organoleptic properties of
prednisolone hybrid nanogel formulations (HN1-
HN9).
Formul
ation
code
Color
Odor
Phase
separa
tion
Homoge
neity
HN1-9
Color
less
Odorl
ess
No
Homoge
neous
3.3.2. Homogeneity measurement
Homogeneity was considered one of the most
important physical attributes that can be used to
evaluate the prednisolone hybrid nanogel
formulations (HN1-HN9), as shown in Table 3,
which indicates the physical stability of all
formulations [20, 21].
Table 2: Summary of characterization results of prednisolone LPHNs formulations (H1-H9).
Formulation
Code
Globule size
(nm)*
PDI*
Zeta
potential*
Entrapment efficiency
% (w/w)*
Drug loading
% (w/w)*
H1
101±3.214
0.409±0.002
35±1.527
87.3±1.5
19.6±2.081
H2
94±2.309
0.389±0.001
36±1.5
86.6±1.52
25.6±1.527
H3
92±3.214
0.317±0.001
43±1.52
81.6±1.527
26.6±2.081
H4
96±2.081
0.405±0.003
35±2.516
86.8±2.645
25.3±2.516
H5
110±1.527
0.455±0.003
26±1.527
88.3±1.35
18.03±1.950
H6
146±1.527
0.51±0.002
15±1.527
89.1±0.680
15.033±1.703
H7
109±3.511
0.434±0.003
32±1.527
88.2±1.365
18.66±2.081
H8
120±1.527
0.468±0.001
25±2.081
88.4±1.252
17.8±1.743
H9
131±1.527
0.505±0.002
18±1.527
88.8±1.001
17.33±2.081
Drais KH / IJPS 2023; 19 (3): 194- 207
202
3.3.3. Measurement of pH
The outcome indicated that pH value lies in the
range (3.936-4.343) as shown in Table 4 is
nearly suitable for topical application [20, 21].
Table 4: Slope and permeation coefficient for
prednisolone hybrid nanogel formulations (HN1-
HN9) and conventional prednisolone gel (G)
through experimental skin membrane.
Formulation
code
Slope
(μg/mL)
Permeability coefficient
(cm/min)
HN1
0.0254
0.00000635±4.93E-09
HN2
0.0257
0.00000642±3.51E-09
HN3
0.0258
0.000006453±3.6E-09
HN4
0.0250
0.00000625±4.5E-09
HN5
0.0241
0.00000626±3.05E-07
HN6
0.0239
0.000005975±1.9E-09
HN7
0.0253
0.00000632±2.5E-09
HN8
0.0251
0.00000627±2.08E-09
HN9
0.0212
0.00000531±9.9E-09
G
0.0179
0.00000635±4.93E-09
3.3.4. Spreadability studies
The spreadability parameter of prednisolone
hybrid nanogel formulations (HN1-HN9) is
related mainly to the concentration of lipid
content, polymeric materials, and PAA-940. It
was an important factor associated with the
ability of the gel to spread through affected skin
and patient compliance. It depended on the
rheology of HN1-HN9. The HN3 formulation
was significantly higher (p-value<0.05) in
spreadability and was significantly lower (p-
value<0.05) in spreadability for (HN9), as
shown in Table 5.
3.3.5. Viscosity measurement
A rotational digital rheometer with a spindle
number (2) from Biobase Meihua Trading Co.,
Ltd. measured viscosity successfully, as shown in
Table 6.
Table 5: Summary of evaluation results of prednisolone hybrid nanogel formulations (HN1-HN9).
Formulation
code
pH*
Spreadability
(g*cm/sec) *
Viscosity (1.5
RPM)* (mP.s)
Release of
prednisolone**
Permeability
coefficient* (cm/min)
HN1
4.343±0.045
125.366±0.251
19305±1.527
80.836±0.03
0.00000635±4.93E-09
HN2
4.256±0.025
113.652±0.02
19307±1.527
81.45±0.036
0.00000642±3.51E-09
HN3
4.153±0.025
104.162±0.035
19310±2.081
88.025±0.003
0.000006453±3.6E-09
HN4
4.046±0.045
62.54±0.026
19327±1.527
74.846±0.035
0.00000625±4.5E-09
HN5
4.246±0.041
59.528±0.005
19334±1.527
73.44±0.036
0.00000626±3.05E-07
HN6
4.15±0.04
56.828±0.01
19345±1.527
72.63±0.02
0.000005975±1.9E-09
HN7
3.936±0.04
92.582±0.009
19347±1.527
76.733±0.0208
0.00000632±2.5E-09
HN8
3.943±0.02
52.089±0.004
19347±2.081
75.064±0.004
0.00000627±2.08E-09
HN9
4.163±0.025
35.718±0.005
19364±2.645
70.195±0.004
0.00000531±9.9E-09
* at 12 hours Values are expressed as mean ± SD (n=3). ** Release of prednisolone as cumulative persent in
phosphate buffer pH 7.4 + 0.3 % polysorbate 80 solutions.
Hybrid Nanogel of Prednisolone
203
Various parameters were obtained:
viscosity, shear rate, and shear stress, using
different rotating speeds. When the shear
rate was plotted against shear stress, a
rheogram chart was achieved, as shown in
Figure 1.
All prednisolone hybrid nanogel formulations
(HN1-HN9) show non-Newtonian plastic flow due
to no gel flowing related to shear stress until it
reaches a specific transition point. The ANOVA
confirmed a significant relationship (p<0.05)
between viscosity and PEG-laurate, lipid content,
and chitosan.
Table 6: Spreadability coefficient for prednisolone
hybrid nanogel formulations (HN1-HN9).
Formulation code
Time
(sec)
Spreadability
coefficient
(g * cm/sec)
HN1
2
125.366±0.251
HN2
2.2
113.652±0.02
HN3
2.4
104.162±0.035
HN4
4
62.54±0.026
HN5
4.2
59.528±0.005
HN6
4.4
56.828±0.01
HN7
2.7
92.582±0.009
HN8
4.8
52.089±0.004
HN9
7
35.718±0.005
Figure 1. Graph representing proximate analysis of
marve seed with the chia seed.
3.3.6. In-vitro diffusion studies
The release of prednisolone forms the prednisolone
hybrid nanogel formulations (HN1-HN9), and
conventional prednisolone gel (G) was studied by
the Franz diffusion cell method using a dialysis bag
as a diffusion membrane.
The diffusion media was phosphate buffer
pH 7.4+0.3% polysorbate 80 solutions.
According to the experimental data, there is no
bust diffusion from all the prednisolone hybrid
nanogel formulations (HN1-HN9) and
conventional prednisolone gel (G). There was a
sustained release process over 24 hours from all
formulations. The profile of prednisolone release
was significantly higher (p-value < 0.05) in the
dissolution rate for HN3 and was significantly
lower (p-value < 0.05) in the dissolution rate of
(G), as shown in Figure 2.
Figure 2. In vitro drug release profile from prednisolone
hybrid nanogel formulations (HN1-HN9) and
conventional prednisolone gel (G) at phosphate buffer
pH 7.4 + 0.3 % polysorbate 80 solution.
The comparability profile of the prednisolone
release from the prednisolone hybrid nanogel
formulations (HN1-HN9) and conventional
prednisolone gel (G) was in the following
descending order: HN3 > HN2> HN1 > HN7 >
HN8 > HN4 > HN5 > HN6 > HN9 > G. The
ANOVA has confirmed a significant
relationship (p<0.05) between diffusion of
prednisolone and independent variables.
Drais KH / IJPS 2023; 19 (3): 194- 207
204
3.3.7. Skin irritation test
The skin irritation experiment was achieved
successfully. There was no erythemic reaction at
the site of sheep skin application. It ascertains the
safety of optimized HN1-HN9 formulations on
biological membranes [21].
3.3.8. Ex-vivo skin permeation study
The permeability coefficient (cm/min) was
calculated after obtaining prednisolone flux
(μg/mL) from the data of an experiment. The
experimental results of the ex-vivo skin
permeation parameter indicated that the
permeability coefficient (cm/min) of
prednisolone was significantly higher (p-value
<0.05) for HN3 and was significantly lower (p-
value < 0.05) for conventional prednisolone gel
(G) as shown in Table 5. The comparability
profile of the prednisolone release from the
prednisolone hybrid nanogel formulations
(HN1-HN9) and conventional prednisolone gel
(G) was in the following descending order:
HN3>HN2>HN1>HN7>HN8>HN4>HN5>HN
6>HN9>G as shown in Figure 3.
Figure 3. Permeation of bioactive agent from
prednisolone hybrid nanogel formulations (HN1-HN9)
and conventional prednisolone gel (G) through the
experimental skin membrane.
The conventional prednisolone gel (G) gave a
lower permeation coefficient than all prednisolone
hybrid nanogel formulations (HN1-HN9) because
HN1-HN9 contained nanoparticles loaded with
prednisolone. The ANOVA explained a significant
(p-value <0.05) relationship between ex-vivo
intestinal permeation parameters and independent
factors. A summary of evaluation results of
prednisolone hybrid nanogel formulations (HN1-
HN9) is shown in Table 6.
The physical hybridization process between
polymeric nanocarriers and lipid-based
nanocarriers gave a drug delivery system that was
rigid in composition but very flexible regarding
prednisolone release. The outcomes of
characterization indicate that all globules of
prednisolone LPHN (H1-H9) formulations had
been distributed in nanometer size, indicating a
colloidal disperse system. The PDI indicated that
prednisolone LPHN (H1-H9) formulations are
homogenous. According to the thumb rule, the zeta
potential absolute values are: 5 mV show fast
aggregation, about 20 mV supply only short-term
stability, above 30 mV offer good stability, and 60
mV excellent stability. Theoretically, the
prednisolone LPHN (H1-H9) formulations should
have a high surface charge to avoid aggregation
during the collision in the colloidal solutions. This
rule applies to nanoparticulated systems that
depend on DLVO forces to evaluate the physical
stability. Prednisolone LPHN (H1-H9)
formulations depend on non-DLVO forces, which
are steric forces and hydration forces, to achieve
pharmaceutical physical stability; therefore,
despite the low value of zeta potential, it was
shown that non-DLVO forces achieved high
stability due to the stabilization process. Also, the
thumb rule applies to the electric stabilization of
Hybrid Nanogel of Prednisolone
205
small molecular weight particles but not to large
molecular weight particles such as PEG-laurate,
which are nonionic stabilizers that present in
prednisolone LPHN (H1-H9) formulations
[15, 23].
In entrapment efficiency, it was found that an
increase in the quantity of lipid contents, which
are cardamom oil, coconut oil, and lauric acid
(3:1:1), leads to an increase in entrapment
efficiency and a decrease in felodipine loading at
a constant concentration of surface-active agents:
co-surfactant blend. It is due to an increment in
the lipid content area available for prednisolone
encapsulation [15]. In evaluating prednisolone
hybrid nanogel formulations (HN1-HN9), the
organoleptic properties reflect the colloidal
structure of the nanosystem and indicate high
physical stability [20, 21]. The outcome of pH
indicated that the pH value was suitable for
topical application [20, 21]. The spreadability
parameter decreases as the viscosity of
formulations increases [21]. The plastic flow of
HN1-HN9 provided easy wiping on the ulcerated
and infected skin or membranes. It was found that
the concentration of lipid increases leads to
increased viscosity due to increased volume
concentration of nanoparticles that make HN1-
HN9 more flow resistant. Also, as gel base
polymer increases, it leads to increased viscosity
due to decreased distilled water content and
increased carbomer-940 concentration that
intertwines with chains of PEG to provide great
flow resistance [15, 21]. It was observed that the
conventional prednisolone gel (G) gave a lower
dissolution rate of felodipine profile in
comparison to all prednisolone hybrid nanogel
formulations (HN1-HN9) due to that HN1-HN9
formulations have nanocarriers which provide a
large surface area in contact to the phosphate
buffer pH 7.4 + 0.3 % polysorbate 80 solutions
and this was permitted a higher interaction area
with the diffusion medium that increases rate of
dissolution [21, 23]. There was no erythemic
reaction at the site of sheep skin application.
Spireas S and Srinivas S (1998) found that
prednisolone loaded to liquisolid compacts
exhibited higher medication discharge rates in
various disintegration media and volumes,
contrasted with tablets arranged by the direct
compression technique. Zakeri P et al. (2011)
prepare solid dispersion of an ineffectively
water-dissolvable medication, prednisolone, to
enhance the dissolution rate. Parikh Harshil et al.
(2022) state that these nanoparticles offer
enormous potential for accomplishing the target
of controlled and site-explicit prescription. It can
reduce undesirable consequences and toxic
effects of medication methods compared to
polymer counterparts. The literature review
provided the different techniques for enhancing
prednisolone solubility. The conducted research
was designed and prepared prednisolone LPHN
(H1-H9) formulations that used to create hybrid
nanogels (HN1-HN9) formulations to improve
prednisolone solubility and hydrophobicity to
facilitate the passage of therapeutic agents across
the biological membrane that led to increase in
therapeutic activity [14, 15].
4. Conclusion
The hybrid nanogel was designed and prepared
successfully. The hybrid gel depended on
LPHNs as a preparation base. All optimized
HN1- HN9 formulations exhibited good
physical stability due to passage through
thermodynamics tests. The outcomes of
Drais KH / IJPS 2023; 19 (3): 194- 207
206
characterization processes for (H1-H9)
formulation were nanosize particle, accepted
PDI, good zeta potential, entrapment
efficiency, and drug loading that reflect the
success of nano delivery system as a structural
base for hybrid nanogel. The evaluation process
for (HN1-HN9) formulations shows good
organoleptic properties, homogenous, optimum
pH, easy spreadability, plastic program, no
burst release with sustained drug release, no
irritation on experimental skin membrane, and
enhanced permeability coefficient. The
characterization and evaluation processes
emphasized that optimized HN1-HN9
formulations were promised drug delivery
systems for treating canker and other oral
lesions in addition to local and transdermal
delivery of various therapeutic agents and
cosmetics.
Acknowledgments
None.
Conflict of interest
The authors declare to have no conflict of
interest.
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