The
stirring is continued for 2 hrs with gradual cooling, the product is
refrigerated overnight for rigidisation, filtered
through whatman filter paper No.1, washed with water
and air- dried. Process variables such as various lipids, their ratios effect
of stirring speed on particle size was evaluated is given in the Tables 1 and
2.
Drug content determination:
Microspheres
equivalent of 10 mg of drug was dissolved in chloroform: alcohol (1:1) by
gentle warming, cooled, filtered and diluted with same solvents and measured
its absorbance at 260 nm using dummy microspheres in the same solvent system as
blank (Tables 3).
Table 3: Drug
content data
|
Formulation code |
Drug content % |
|
F1 |
56.57 |
|
F2 |
62 |
|
F3 |
69.62 |
|
F4 |
67.92 |
|
F5 |
89.86 |
Based on the drug content F5 formulation was selected
for further evaluation of microspheres.
Fig: 1 comparative in vitro dissolution
data
Evaluation of microspheres:
In vitro dissolution studies:
In
vitro dissolution studies were carried out by using type II apparatus using 100
ml phosphate buffer as dissolution media. A micro sphere equivalent to 20 mg of
drug was placed in the dissolution jars of apparatus and dissolution was
carried out at 100 rpm at 37°C. The samples were withdrawn at regular time
intervals and replaced with fresh buffer and analysed
spectrophometrically at 260 nm using phosphate buffer
as blank. Result is compared with pure drug and marketed gel of 2.5% ketoprofen. Results are shown in the Fig 1
Scanning electron microscope:
The Scanning Electron Microscope (SEM) used for the
study was model JEOL JSM 840 A. Cleaned brass specimen studs were used for
mounting the samples. Wet solvent paint was applied on these brass specimen
studs and while the paint was wet, the samples were placed on each stud and
allowed to dry. Then the sample was put in the SEM and photographs were taken.
(Fig 2 and 3)
Fig 2: SEM of
microspheres prepared at 200 rpm
Particle size
determination:
Particle
size and size distribution of around 100 microspheres of formulation F5 at two
different rpm were analysed by optical microscopy
method shown in Fig 4 and 5
Fig 3: SEM of
microspheres prepared at 500 rpm
Fig: 4 Histogram
of lipid microspheres at 200 rpm
Fig: 5 Histogram
of lipid microspheres at 500 rpm
In-vitro diffusion studies:
In-vitro
diffusion studies were carried out means of diffusion cell assembly using
previously treated (0.1N HCl) cellophane membrane.
Microsphere equivalent to 5 mg of drug and 1 ml of phosphate buffer was placed
in cellophane membrane which was tied to the mouth of the modified diffusion
cell assembly having an area of 2.84 cm2 and 100 ml of phosphate buffer
as the receptor media. Samples were withdrawn at regular intervals, replaced
with fresh buffer and analysed for drug content at
260 nm spectrophotometrically using phosphate buffer
as blank. The diffusion data after 10 hrs of study is was compared with pure
drug and marketed gel of ketoprofen. Results shown in
the table 4
Permeability studies:
Permeability
studies were carried out using excised rat abdominal skin from wistar rats of age group 2-3 months. The animals were anaesthetized;
abdominal skin was collected, washed in running water, dipped into ammonia
solution, and washed with distilled water until ammonia got completely removed.
The collected skin was placed in physiological solutions.
Microspheres equivalent to 5 mg of drug and 1 ml of
phosphate buffer was placed on skin which was tied to the mouth of the
diffusion cell assembly having a surface area of 2.84 cm2 and 100 ml
of phosphate buffer pH 7.4 as receptor media. Samples were collected at regular
intervals and replaced with fresh buffer and analysed
for drug at 260 nm spectrophotometrically using
phosphate buffer as blank. Comparative cumulative release after 10 hrs of study
is shown in the table 5.
Table 4: in
vitro –diffusion data
|
Formulation |
Cumulative release (%) |
|
Microspheres |
92.12 |
|
Pure Drug |
96.62 |
|
Marketed Gel |
40.90 |
Table 5:
permeation data
|
Formulation |
Cumulative
release (%) |
|
microspheres |
66.87 |
|
pure drug |
99.81 |
|
Marketed gel |
44.72 |
From the above data obtained, flux data was calculated
By the equation J= dm/S.dt,
where m is the amount of drug passing through the membrane, S is the surface
area of the membrane and t is the time of diffusion through the membrane. The
data is as shown in the table 6.
Table 6: Comparative flux data of the formulations
73TTtT4
|
Sl. No. |
Formulation |
Surface area (cm2) |
Dm/dt |
Flux (cm-2/sec) |
|
1 |
Microsphers
C |
2.84 |
0.3208 |
1.88 x10-2 |
|
2 |
Microsphers
S |
2.84 |
0.2333 |
1.369 x10-2 |
|
3 |
Pure
drug C |
2.84 |
0.7535 |
1.99 x 10-2 |
|
4 |
Pure
drug S |
2.84 |
0.5893 |
3.46 x10-2 |
|
5 |
Marketed
gel C |
2.84 |
9.1693 |
0.09 x10-2 |
|
6 |
Marketed
gel S |
2.84 |
0.1246 |
0.083 x10-2 |
C-diffusion through cellophane membrane, S- permeation
through skin
RESULTS AND DISCUSSION:
Microspheres prepared by emulsification procedure by
using different waxes. They were studied for in- vitro dissolution
characteristics showed that 93% of the drug is been released in 10 hrs.
The in vitro diffusion behavior
was studied using treated cellophane membrane 91.53% was released in 10 hrs.
Permeation behavior using excised
rat abdominal skin 64.60% was released in 10 hrs.
Particle size analysis of
formulation at two different rpm i.e. at 200 and 500 and found that stirring
rate affected the particle size.
Different techniques like TLC,
SEM and IR were done for the characterization of microspheres.
The permeation of microspheres and
pure drug was compared with marketed gel of ketoprofen
(2.5 %) and seen that rate of permeation of microsphere was found to be more
when compared to marketed formulation.
CONCLUSION:
The
lipid microsphere of ketoprofen was found to increase
the drug permeability thus increasing the rate and extent of its permeation,
lipid microspheres are easy to prepare and to scale-up. So lipid microspheres
of ketoprofen have the potential as novel carrier
systems for optimizing the topical drug therapy in the treatment of arthritis
and associated symptoms.
REFERENCES:
1.
Martindale, 2002. The complete drug reference, 33rd edition
Pharmaceutical press, Great Britain, pp: 47-50.
2.
Venketeswarulu.V. and Patllor. R. 2001. Lipid
microspheres as drug delivery system.
Indian Journal of Pharmaceutical Sciences, 63(6), 450- 458.
3.
Wissing.S. A., Muller. R., H., 2002. Solid lipid nanoparticles as carrier for sunscreens: in vitro release
and in vivo skin penetration. Journal of Controlled Release 81: 225–233
4.
Claudia Valenta, Marlies
Wanka, Jurgen Heidlas, 2000. Evaluation
of novel soya-lecithin formulations for dermal use containing ketoprofen as a model drug. Journal of Controlled Release, 63:
165–173
5.
Rita Cortesi, Elisabetta
Esposito, Giovanni Luca, Claudio Nastruzzi, 2002.
Production of lipospheres as carriers for bioactive
materials. Biomaterials, 23: 2283-2294.
6.
Jelena Djordjevic, Bozena Michniak, Kathryn E., Uhrich, 2003. Amphiphillic star-
like macromolecules as novel carriers topical delivery
of non steroidal anti-inflammatory drugs. AAPS pharmsci,
5:4
7.
Nadia. P., etal, 2003, Controlled release of verapamil hydrochloride from waxy microparticles by spray
congealing, Journal of Controlled Release, 88:263-275.
Received
on 08.07.2010
Accepted on 02.08.2010
© A&V Publication all right reserved
Research Journal of Pharmaceutical
Dosage Forms and Technology.
2(5): Sept.-Oct. 2010, 340-343