International Journal of Pharmaceutical Sciences and Nanotechnology
Volume 2 • Issue 1 • April – June 2009
Research Paper
Preparation, Optimization and Characterization of
Ketoprofen Proniosomes for Transdermal Delivery
Ajay B Solanki1*, Jolly R Parikh1 and Rajesh H Parikh2
1
Department of Pharmaceutics and Pharmaceutical Technology, A. R. College of Pharmacy & G. H. Patel Institute of
Pharmacy, P.O. Box 19, Vallabh Vidyanagar -388 120 Gujarat, India.
2
Ramanbhai Patel College of Pharmacy, Education campus, Changa 388 421 Gujarat, India.
ABSTRACT: The aim of the present study was to prepare, optimize and characterize ketoprofen proniosomes. The
niosomes were prepared using a slurry method followed by in vitro evaluation after embedding the proniosomes-derived
niosomes into a carbopol matrix. A central, composite Box-Wilson design was used for the optimization with the total lipid
concentration (X1), surfactant loading (X2) and amount of drug (X3) as the independent variables. Prepared proniosomes
were characterized for percentage drug entrapment (PDE) and mean volume diameter (MVD). Multiple regression analysis
and contour plots were used to relate the dependent and independent variables. Checkpoint batches were also prepared to
prove the validity of the evolved mathematical model and contour plots. The optimization model predicted the levels of X1,
X2 and X3 (-1, -0.3 and 0.92, respectively), for a maximized response of PDE with constraints of ≤ 5 μm on MVD. Optimized
batch was used to prepare a niosomal gel, which showed significantly higher cumulative amount of drug permeated and
steady state transdermal flux compared to plain gel. This work has demonstrated the use of the central composite BoxWilson design, regression analysis, and contour plots in optimizing ketoprofen proniosomes. Developed niosomal gel
formulation has also demonstrated permeation enhancement of ketoprofen compared to plain gel.
KEYWORDS:
Proniosomes, Niosomes, Ketoprofen, Central composite Box-Wilson design, Optimization, In vitro
permeation.
Introduction
Drug delivery systems using vesicular carriers such as
liposomes and niosomes have distinct advantages over
conventional dosage forms (Schreier et al., 1994). They
may serve as a solubilization matrix, as local depot, as
permeation enhancer or as a rate limiting membrane barrier
for the modulation of systemic absorption of drugs via the
skin (Fang et al., 2001a). Niosomes are non-ionic
surfactant vesicles that can entrap solute in a manner
analogous to liposomes. All the methods traditionally used
for the preparation of niosomes are time consuming and
many involve specialized equipment (Blazek-Welsh and
Rhodes, 2001a).
A proniosome formulation based on maltodextrin was
recently developed that has potential applications in
delivery of hydrophobic or amphiphilic drugs (BlazekWelsh and Rhodes, 2001b; Hu and Rhodes, 1999). Effect
of different formulation variables on proniosomes
characteristics can be studied using slurry method because
of the ease of production. One of the different mechanisms
* For correspondence: Ajay Solanki
E-mail: ajay_solanki76@yahoo.com
413
of drug permeation through skin from vesicles is direct
transfer of drug from vesicles to skin that occurs only
when the drug is intercalated within bilayers (Fang et al.,
2001b). To achieve better permeation of drug through skin
it is desired to prepare a proniosomes with maximum drug
entrapment. Many formulation variables like lipid
concentration, surfactant loading, and amount of drug may
affect the characteristics of proniosome-derived niosomes.
The proniosomes are thus of interest from a technical point
of view and need to be optimized for desired response.
Hence, in the present study total lipid concentration (X1),
surfactant loading (X2) and amount of drug (X3) were
selected as independent variables and optimized for the
percentage drug entrapment (PDE) and mean volume
diameter (MVD) using central composite Box-Wilson
design. Vesicles are usually applied to the skin as liquids
or gels (Alsarra et al., 2005). For transdermal application
of vesicles in gel form, hydrophilic polymers are
compatible and considered to be suitable thickening
agents.
Ketoprofen is a nonsteroidal anti-inflammatory drug
with well-established analgesic and antipyretic properties.
It is widely used in the treatment of rheumatoid arthritis,
414
International Journal of Pharmaceutical Sciences and Nanotechnology
osteoarthritis, and a variety of other acute and chronic
musculoskeletal disorders (Kantor, 1986). Oral therapy of
ketoprofen is very effective, but the clinical use is often
limited because of the adverse effects such as irritation and
ulceration of the gastro intestinal tract. Ketoprofen
possesses lower molecular weight (254.29) and relatively
short half-life (1-3 hours) in plasma, and has the potential
to be delivered topically. The transdermal drug delivery
has been considered to be ideal route for ketoprofen
administration (Wu et al., 2001).
Therefore, the present study was aimed at optimizing
ketoprofen proniosomes for desired response followed by
in vitro evaluation after embedding the proniosomederived niosomes in to a carbopol matrix with a view to
improve the penetration of drug.
Materials and Methods
Span 40 and cholesterol were purchased from S.D. Fine
Chemicals. (Mumbai, India). Ketoprofen was received as a
gift sample from Alembic chemicals. (Vadodara, India).
Diethyl ether, disodium hydrogen phosphate, potassium
dihydrogen phosphate and sodium chloride were procured
from National Chemicals. (Vadodara, India). Dialysis tube
(DM-70; Capacity: 2.41ml/cm, width: 29.31 mm, Avg.
diameter 17.5 mm and molecular weight cut off: 12000 to
14000) was purchased from Himedia Laboratories.
(Mumbai, India). All chemicals used in the study were of
analytical grade and used without further purification. Rats
(albino, wistar strains) were kindly provided by Cadila
Pharmaceutical ltd. (Ahmedabad, India).
Experimental Design
A central, composite Box-Wilson design consists of 8 full
factorial design points, 6 axial points, and 6 center points
(Li et al., 2001). Independent variables with their levels
and the dependent variables selected are listed in the Table 1.
The Polynomial equation generated by this experimental
design using Microsoft Excel is described as equation 1:
Volume 2 • Issue 1 • April - June 2009
Where Yi is the dependent variable while b0 is the
intercept; b1 to b33 are the regression coefficients; and X1,
X2 and X3 are the independent variables (Box and
Behnken, 1960) and levels of independent variables were
selected from the preliminary experiments.
Preparation of proniosomes
Proniosomes were prepared by the slurry method (BlazekWelsh and Rhodes, 2001a). 250 mmol stock solution of
span 40 and cholesterol were prepared in the diethyl ether
for the ease of preparation. All the batches were prepared
according to experimental design given in Table 2. The
required volume of span 40 and cholesterol stock solution
per gram of carrier and drug dissolved in diethyl ether
were taken in to 100 ml round bottom flask containing
maltodextrin as a carrier. Additional diethyl ether was
added to form slurry in case of lower surfactant loading.
The flask was attached to rotary flash evaporator (EIE-R,
India.) to evaporate diethyl ether at 60-70 rpm, under 200
mm of Hg vacuum until mass in the flask resulted in a dry
free flowing product. These prepared proniosomes were
used for niosomes preparation and surface characterization
by scanning electron microscopy (SEM).
Proniosomes were transformed to niosomes by
hydrating with phosphate buffer saline (PBS) pH 7.4 at 80
0
C using vortex mixer for 2 minutes. The niosomes were
sonicated twice for 30 seconds using a 250-W probe-type
sonicator (MAGNA-PAK-250, Libra Ultrasonic, India).
Niosomes were characterized for morphology, PDE and
vesicle size in terms of MVD.
Proniosome-derived niosomes (optimized batch) were
used to prepare niosomal gel. For this purpose equivalent
amount of niosomal suspension containing 0.5 g drug was
centrifuged and the pellets obtained were mixed with 0.9%
w/v carbopol dispersion and made it viscous using 5% w/v
triethanolamine solution. This prepared niosomal gel was
subjected to in vitro permeation study.
Yi = b0 + b1X1 + b2X2 + b3X3 + b12X1X2 + b13X1X3 +
(1)
b23X2X3 + b11X12 + b22X22 + b33X32
Table 1 Independent variables with their levels in Central Composite Box-Wilson design.
Independent variables
Levels
Low
Medium
High
10 mmol
15 mmol
20 mmol
X2 = Surfactant loading
1.5 X
3X
4.5 X
X3 = Amount of drug
4 mg
6 mg
8 mg
Transformed values
-1
0
1
X1 = Total lipid concentration
Y1 = Percentage drug entrapment
Y2 = Mean Volume Diameter
Ajay Solanki B et al. : Preparation, Optimization and Characterization of Ketoprofen Proniosomes for Transdermal Delivery
415
Table 2 Central Composite, Box-Wilson design with measured responses.
Batch Code
X1
X2
X3
PK1
-1
-1
-1
PK2
1
-1
-1
PK3
-1
-1
1
PK4
1
-1
1
PK5
-1
1
-1
PK6
1
1
-1
PK7
-1
1
1
PK8
1
1
1
PK9
-1.68
0
0
PK10
1.68
0
0
PK11
0
0
-1.68
PK12
0
0
1.68
PK13
0
-1.68
0
PK14
0
1.68
0
PK15
0
0
0
PK16
0
0
0
PK17
0
0
0
PK18
0
0
0
PK19
0
0
0
PK20
0
0
0
PDE* ± SD
71.64 ± 2.32
MVD (μm)
56.81 ± 1.35
5.85
82.62 ± 1.8
3.88
73.69 ± 2.46
4.2
69.17 ± 1.42
6.29
79.51 ± 1.93
54.48 ± 2.54
5.87
74.54 ± 2.68
59.5 ± 1.24
8.08
78.63 ± 1.75
5.28
79.8 ± 1.12
61.22 ± 1.64
5.81
69.88 ± 1.46
4.12
68.86 ± 1.3
5.48
67.4 ± 1.78
5.29
71.7 ± 1.57
4.74
6.9
7.16
5.86
69.26 ± 2.04
7.13
71.54 ± 1.62
5.42
70.3 ± 1.57
69.84 ± 1.2
5.37
5.43
6.1
*n = 3
Optical Microscopy
The morphology of hydrated niosomes was observed using
optical microscope (Medilux-207R (II), Kyowa-Getner,
India). The niosome dispersion after suitable dilution was
mounted on glass slide and viewed under a microscope
with a magnification of 1200X.
Determination of PDE
Ketoprofen within proniosome-derived niosomes was
estimated after removing unentrapped drug by the method
of dialysis (New, 1990). The dialysis was carried out by
taking niosomal dispersion in dialysis tube (donor
compartment), which was dipped in a beaker containing
400 ml of PBS pH 7.4 (receptor compartment). The beaker
was kept on a magnetic stirrer, rotated at a speed of 80 120 rpm and run for 4 hours. After 4 hours, the solution of
receptor compartment was estimated for unentrapped
ketoprofen at 261 nm using an UV spectrophotometer (UV
1601, Shimadzu, Japan). The PDE in the niosomes was
calculated from the ratio of the difference of the total
amount of drug added and amount of unentrapped drug
detected to the total amount of drug added.
Measurement of vesicle size
The vesicle dispersion was diluted about 100 times in the
same buffer, used for their preparation. Vesicles size was
measured as MVD on a particle size analyzer (Laser
diffraction particle size analyzer, Sympatec, Germany).
The apparatus consist of a He-Ne laser beam of 632.8 nm
focused with a minimum power of 5 mW using a fourier
lens [R-5] to a point at the center of multielement detector
and a small volume sample holding cell (Su cell) The
sample was stirred using a stirrer before determining the
particle size.
In vitro skin permeation study (optimized batch)
The abdominal hair of albino rats (wistar strain), weighing
200 ± 20 gm, was shaved using hand razor. After
anesthetizing the rats with ether, the abdominal skin was
surgically removed from the animal, and adhering
subcutaneous fat was carefully cleaned. To remove
extraneous debris and leachable enzymes, the dermal side
of the skin was kept in contact with a physiological saline
solution for 1 h before starting the permeation experiment.
The in vitro rat skin permeation study was carried out
as per the guidelines compiled by CPCSEA (Committee
for the Purpose of Control and Supervision of Experiments
on Animal, Ministry of Culture, Government of India) and
all the study protocols were approved by the local
institutional Animal Ethics Committee. The permeation of
drug from niosomal gel formulations was determined by
416
International Journal of Pharmaceutical Sciences and Nanotechnology
using Franz diffusion cell. The excised rat skin was
mounted on the receptor compartment with the stratum
corneum side facing up-wards into the donor compartment.
The donor compartment was filled with the niosomal gel
formulation. A 15 ml of pH 7.4-phosphate buffer
containing 10% PEG was used as receptor medium to
maintain a sink condition. The available diffusion area of
cell was 3.14 cm2. The receptor compartment was
maintained at 37 ± 1 0C, with magnetic stirring at 600 rpm.
The samples from the receptor compartment were
withdrawn at predetermined time intervals and
immediately replaced by an equal volume of fresh buffer
solution. Initial experiments confirmed the maintenance of
sink condition by this procedure. The samples withdrawn
from the receptor compartment were then analyzed by
using U V spectrophotometer.
Volume 2 • Issue 1 • April - June 2009
Results and Discussion
Maltodextrin was used as a carrier for the preparation of
proniosomes. SEM images (Figure 1) of uncoated
maltodextrin and proniosomes powders showed differences
in the surfaces. Comparison of the proniosomes images
revealed that the surface of the carrier particles at medium
level of surfactant loading (Batch PK15) appeared to be
smoother, continuous and more uniform than the
incomplete film coating at low surfactant loading (Batch
PK2). This may be due to more amount of carrier present
than required for coating of the surfactant mixture at low
level of surfactant loading. Niosomes were observed
mostly spherical in shape with few being slightly elongated
in the optical micrograph (Figure 2).
Fig. 1 Scanning electron micrographs of various batches of ketoprofen proniosomes.
Fig. 2 Optical photomicrograph of proniosome-derived niosomes (Batch PK2)
Ajay Solanki B et al. : Preparation, Optimization and Characterization of Ketoprofen Proniosomes for Transdermal Delivery
term total lipid concentration (X1) for PDE represents a
favourable effect. This may be due to more availability of
the surfactant at high level of X1 resulting in A high value
of PDE. A negative signs for the coefficient of the terms
X2 and X3 indicate antagonistic effect of these variables on
PDE of ketoprofen proniosomes. A positive signs for the
coefficient for all three key variables indicate favorable
effect on MVD.
A Central, composite Box Wilson experimental design
using three independent variables at their three different
levels was used to study their effects on the dependent
variables. This design offers an advantage of fewer
experimental runs (20 runs) as compared with that of 33
full factorial design, which requires 27 runs (Box and
Behnken, 1960). All the batches of proniosomes were
prepared as per the experimental design and then hydrated
to form niosomes. Transformed values of all the batches
along with their responses are shown in Table 2. PDE
value of different formulations showed wide variation i.e.
from minimum 54.48% to maximum 82.62%. This clearly
indicates that the selected independent variables have a
profound effect on the PDE within proniosome-derived
niosomes. Formulations PK2, PK6, PK10 and PK11
exhibited high PDE value i.e. > 75%.
As illustrated in Table 4, a P value of ≤ 0.05 for
independent variables and their interaction in analysis of
variance (ANOVA) indicates significant effect of the
corresponding factors on the PDE and MVD. The terms
X1, X3 and X1X3 having a P < 0.05 (Table 4) indicate
significant effect of these terms on PDE of ketoprofen
proniosomes. Further, from the results of ANOVA, it is
clear that the terms X1, X2, X3 and X2X3 having significant
effect (P < 0.05) on the MVD (Table 4).
The fitted equations relating the responses PDE and
MVD to the transformed factors are shown in Table 3. The
polynomial equations can be used to draw conclusions
after considering the mathematical sign and magnitude of
coefficient. The value of the correlation coefficient (r2) for
PDE and MVD was found to be 0.98 and 0.9 respectively,
indicating good fit. A positive sign of the coefficient of the
As this design includes extra center points, we can
estimate the pure error, and test for overall lack of it is
fitness. As shown in Table 4, the test for lack of fit does
not yield statistical significance (P > 0.05) for both PDE
and MVD, and hence, we can be assured that the current
model provides a satisfactory fit to the data.
Table 3 Summary of Results of Regression Analysis.
Coefficient
b0
b1
b2
b3
b12
b13
b23
b11
b22
b33
PDE
69.53
6.63
-0.74
-5.46
0.32
1.95
0.51
-0.13
0.48
0.38
MVD
5.52
0.70
0.76
0.38
-0.22
0.02
0.45
0.21
-0.002
0.07
Table 4 Summary of Results of Analysis of Variance (ANOVA)*.
Source
DF
PDE
SS
MS
MVD
F
P
SS
MS
F
P
X1
1
598.90
598.90
292.74
0.00
6.65
6.65
30.26
0.00
X2
1
7.50
7.50
3.67
0.08
7.97
7.97
36.24
0.00
X3
1
408.24
408.24
199.55
0.00
1.99
1.99
9.06
0.01
X1X2
1
0.81
0.81
0.39
0.54
0.38
0.38
1.74
0.22
X1X3
1
30.50
30.50
14.91
0.00
0.00
0.00
0.02
0.90
X2X3
1
2.10
2.10
1.03
0.33
1.63
1.63
7.41
0.02
X1
2
1
0.26
0.26
0.13
0.73
0.63
0.63
2.86
0.12
X2
2
1
3.27
3.27
1.60
0.24
0.00
0.00
0.00
0.99
X3
2
1
2.05
2.05
1.00
0.34
0.08
0.08
0.35
0.57
Lack of Fit
5
10.67
2.13
1.09
0.46
1.77
0.35
4.10
0.07
Pure Error
5
9.79
1.96
0.43
0.09
19
1074.00
Total SS
417
21.51
*SS indicates: sum of squares; DF, degree of freedom; MS, mean of squares; F, Fisher’s ratio.
418
International Journal of Pharmaceutical Sciences and Nanotechnology
Contour plots
Two-dimensional contour plots were established using
coefficient of the various terms (Table 3). Values of
independent variables were computed at prefixed values of
PDE and MVD and two contour plots were constructed at
fixed medium level of X2 (Figure 3) and at low level of X1
(Figure 4). It is evident from the Figure 3, all the contours
for PDE (above 63% value) and MVD were found to be
Volume 2 • Issue 1 • April - June 2009
nonlinear indicating nonlinear relationship between X1 and
X3 variables. From the Figure 4 the following observations
can be made. All the contour plots are found to be
curvilinear signifying non-linear relationship between X2
and X3. Low value of MVD could be obtained for different
combination of X2 with less than 0.5 level and X3 with
entire range and high value of PDE can be obtained with
low levels of both independent variables.
Fig. 3 Combined contour plot for PDE and MVD of proniosome-derived niosomes at medium level of X2.
Fig. 4 Combined contour plot for PDE and MVD of proniosome-derived niosomes at low level of X1.
Ajay Solanki B et al. : Preparation, Optimization and Characterization of Ketoprofen Proniosomes for Transdermal Delivery
Checkpoint analysis
Three checkpoint batches were prepared and evaluated for
PDE and MVD as shown in Table 5. Results indicate that
the measured PDE and MVD values were as expected.
When obtained responses were compared with the
predicted PDE and MVD value from coefficients and
419
contour plots, using student’s t-test, the differences were
found to be insignificant (P> 0.05). Thus, we can conclude
that the obtained coefficients and plotted contour plots are
valid in predicting the levels of independent variables for
desired response.
Table 5: Checkpoint Batches of ketoprofen proniosomes with their Measured and Predicted value of PDE and
MVD.
Batch code
X1
PKC1
PKC2
PKC3
PDE
MVD
X2
X3
-0.5
0
-0.5
67.81 ± 1.62
69.495
5.18
5.05
-1
-0.5
0.5
60.75 ± 0.84
59.6825
4.79
4.62
-1
-0.5
0
60.34 ± 2.14
62.8242
4.82
4.98
Measured*
Predicted
Measured
Predicted
*n = 3
Optimum formula
In vitro permeation study
After studying the effect of the independent variables on
the responses, the levels of these variables, which give the
optimum response, were determined. It is evident from
results of ANOVA (Table 4) that the term surfactant
loading (X2) having least contributing effect in predicting
the PDE of ketoprofen proniosomes. Also, Figure 3 shows
that the high value of PDE could be obtained with a low
level of term X1 and X3. The optimum formulation is one
that gives a high value of PDE and constraints on MVD
(≤ 5 μm) along with a high total amount of drug entrapped
and a low amount of carrier in the resultant niosomes. To
achieve this, it is necessary to find out the optimum level
of terms X2 and X3, which should be as high as possible at
any level of X1 (Table 3 and Figure 3, 4). Low level of X1
was selected as an optimum as at this level less than 5 μm
MVD value can be obtain up to a 0.05 level of X2 and high
level of X3. Using a computer optimization process and the
contour plot shown in Figure 4, the levels selected for X1,
X2 and X3 were –1, –0.3 and 0.92 respectively, which gives
the theoretical value of 56.51% and 4.99 μm for PDE and
MVD respectively. Below the selected (optimum) level of
X2 and X3 a high value of PDE could be obtained, but total
amount of drug entrapped would significantly decreases.
Proniosomes were prepared at the optimum levels (-1 level
of X1, -0.3 level of X2 and 0.92 level of X3) of the
independent variables and the resultant proniosomes
transformed to niosomes and evaluated for the responses.
The observed value of PDE and MVD were found to be
54.82% and 4.92 μm respectively, which were in close
agreement with the theoretical value. This optimum batch
(PKO) was subjected to further evaluation.
In vitro permeation study was performed to predict how a
delivery system might work in an actual situation as well
as give some indications of its in vivo performance since
drug permeate dictates the amount of drug available for
absorption (Gupta et al., 2007). In order to evaluate the
effect of niosomal gel on the ketoprofen permeation rate,
the permeation of ketoprofen from plain gel (ketoprofen
dispersed in carbopol dispersion) was also estimated.
Cumulative amount of drug permeated through skin was
obtained 403.65 μg/cm2 and 346.48 μg/cm2 for niosomal
gel and plain gel respectively. The steady state transdermal
flux from the Fick’s law equation for the gel formulations
across the rat skin was calculated from the slope of the
linear portion of the cumulative drug permeated verses
time plot (2-6 h). The permeability coefficient (Kp) was
calculated from the steady state transdermal flux and the
applied concentration in the donor compartment (Cdonor) as
per equation 4.
Kp = J/ Cdonor
(2)
Steady state transdermal flux and Kp from niosomal gel
were found to be significantly (P<0.05) higher (50.81
μg/cm2 h-1 and 5.74X 10-3 cm/h respectively) than from the
plain gel (38.12 μg/cm2 h-1 and 3.81 X 10-3 cm/h
respectively).
Above experimental results confirm the ability of
niosomes to alter the therapeutic effect of ketoprofen. The
encapsulation of ketoprofen in niosomes produced an
enhancement of permeation compared with plain gel.
Higher cumulative amount of drug permeated and steady
state transdermal flux from the niosomal gel formulation
can be explained by solubilization and penetration
enhancement effect of amphiphiles of the niosomes
bilayer. Furthermore, after 2 h, high correlation coefficient
HEC1
420
International Journal of Pharmaceutical Sciences and Nanotechnology
was obtained for the zero order drug permeation from the
niosomal gel. This suggests that niosomes can act as
reservoir system, similar to a constant release vehicle,
enabling more uniform and prolonged release of the drug.
So, a high topical concentration of the drug can be
maintained when compared with conventional vehicles.
Also the use of niosomes may disrupt the membrane
properties of stratum corneum (Touitou et al., 1994) or
fusion of niosomes at the surface of skin results in higher
flux of the drug due to direct transfer of drug from vesicles
to the skin (Barry, 2001).
Conclusion
This work has demonstrated the use of central composite
Box Wilson design, regression analysis, and contour plots
in optimizing formulation variables in the preparation of
ketoprofen proniosomes by the slurry method. Optimized
batch of proniosomes was used for the preparation of
niosomal gel by incorporating hydrated niosomes to
carbopol matrix. This study suggests that niosomal gel
containing ketoprofen could perform therapeutically better
effects than the conventional formulations, as permeation
enhancement for prolonged period, which may lead to
improved efficiency and better patient compliance.
References
Alsarra IA, Bosela AA, Ahmed SM, and Mahrous GM.
Proniosomes as a drug carrier for transdermal delivery
of ketorolac. Eur J Pharm Biopharm. 59(3): 485-490
(2001).
Barry BW. Novel mechanisms and devices to enable
successful transdermal drug delivery. Eur J Pharm Sci.
14: 101-114 (2001).
Blazek-Welsh AI, and Rhodes DG. Maltodextrin-based
proniosomes. AAPS Pharmsci, 3(1): article 1 (2001a).
Blazek-Welsh AI, and Rhodes DG. SEM Imaging predicts
quality of niosomes from maltodextrin-based
proniosomes. Pharm Res. 18(5): 656-661 (2001b).
Volume 2 • Issue 1 • April - June 2009
Box GEP, and Behnken DW. Some new three level
designs for the study of quantitative variables.
Technometrics. 2: 455-475 (1960).
Fang JY, Hong CT, Chiu WT, and Wang YY. Effect of
liposomes and niosomes on skin permeation of
enoxacin. Int J Pharm. 219: 61-72 (2001a).
Fang JY, Yu SY, Wu PC, Huang YB, and Tsai YH. In
vitro skin permeation of estradiol from various
proniosome formulations. Int J Pharm. 215: 91-99
(2001b).
Gupta A, Prajapati SK, Balamurugan M, Singh M, and
Bhatia D. Design and Development of a Proniosomal
Transdermal Drug Delivery System for Captopril. Trop
J Pharm Res. 6(2): 687-693 (2007).
Hu C, and Rhodes DG. Proniosomes: A novel drug carrier
preparation. Int J Pharm. 185: 23-35 (1999).
Kantor TG. Ketoprofen: a review of its pharmacologic and
clinical properties. Pharm. 6: 93–103 (1986).
Li S, Lin S, Chien YW, Daggy BP, and Mirchandani HL.
Statistical Optimization of Gastric Floating System for
Oral Controlled Delivery of Calcium. AAPS
PharmSciTech. 2(1): article 1 (2001).
New RRC. Liposomes: a practical approach. New York:
Oxford University Press, 1990.
Schreier H, and Bouwstra J. Liposomes and niosomes as
topical drug carriers: dermal and transdermal drug
delivery. J Control Rel. 30: 1-15 (1994)
Touitou E, Junginger HE, Weiner ND, Nagai T, and Mezei
M. Liposomes as carrier for topical and transdermal
delivery. J Pharm Sci. 83: 1189-1203 (1994).
Wu, P.C.; Chang, J. S.; Huang, Y. B.; Chai, C. Y.; Tsai,
Y.H. Evaluation of percutaneous absorption and skin
irritation of ketoprofen through rat skin: in vitro and in
vivo study. Int J Pharm. 222: 225–235 (2001).