PG No. 1:Effect Of
Different Sugar On Surface Characteristics; (A)and(B) – Wavy, (C)and(D) –
Smooth
Table No. 1 Effect of
stirring speed on particle size of GMs of benz-3.
|
S. No. |
Cross Linker |
Particle Size (µm) at |
Different Stirring |
Speed (rpm) |
|
250 |
500 |
750 |
||
|
1 2 3 |
Sucrose Glucose Fructose |
114.8 120.3 104.6 |
96.2 86.3 70.8 |
80.63 45.05 32.6 |
Table
No. 2 Effect of Gelatin Concentration on surface characteristics of
microspheres.
|
S. No. |
Gelatin concentration |
cross linker |
GMs Surface |
|
1 2 3 |
0.75gms 1.5gms 3.0gms |
Sucrose Glucose Fructose Sucrose Glucose Fructose Sucrose Glucose Fructose |
Smooth Wavy Smooth Wavy Smooth Smooth Highly rough Highly rough Highly rough |
Natural polymer such as gelatin has been
extensively used for the preparation of particulate drug delivery system by
virtue of its biocompatibility and biodegradability along with absence of
toxicity or allergic problems. Being a water soluble polymer, gelatin has to be
chemically cross linked to become insoluble at 37ºC. This microspheres can be
efficiently employed in the sustained delivery(1,
3).
Benzophenone-3
(2-hydroxy-4-methoxybenzophenone) is a commonly used sunscreening
agent in the topical formulation to prevent sunburn and may also provide some
protection against drug related or other photosensitive reactions associated
with UVA light. The main effect of Benzophenone-3 is that it absorbs light
throughout the UVB range (290-320nm) and also absorbs some UVA light with
wavelengths of 320-360nm and some UVC light with wavelength of 250-290nm.
Benz-3 is commonly used in a concentration up to 6% w/w(2).
Figure
No. 1 In vitro drug release from microspheres.
Table
No. 3 Effect of Cross Linker on particle size and surface characteristics of
GMs of benz-3
|
S. No. |
Cross Linker |
Particle Size (µm) |
GMs Surface |
|
1 |
Gelatin |
50.32±10.0 |
Wavy |
|
2 |
Gelatin/Glucose |
45.02±7.5 |
Wavy |
|
3 |
Gelatin/Sucrose |
80.63±8.3 |
Smooth |
|
4 |
Gelatin/Fructose |
32.6±4.0 |
Smooth |
Table
No. 4 Effect of Cross Linker on Microencapsulation Efficiency..
|
S. No. |
Cross Linker |
Microencapsulation Efficiency |
|
1 2 3 |
Sucrose Glucose Fructose |
80% 92% 89% |
Materials:
For microspheres- Benzophenone-3
(Fulford (
Methods:
Microencapsulation
method:
Microspheres
were prepared by emulsion cum thermal gelation technique. 10 ml of 15% w/v
gelatin solution containing 5% w/w of sugar, at 80°C, were added to 200ml Soya oil. 500 mg Benzophenone-3
was added to the gelatin solution. The mixture was mechanically stirred to form
o/w emulsion, under laminar flow, after 5 mints the
solution was rapidly cooled at 15°C. 250ml of acetone were added to dehydrate and
flocculate coacervate droplets. The microspheres was isolated by filtration through sintered
glass filter. Residual oil over the microspheres was removed by washing with
250ml of acetone. After preparation of microspheres they were stored at room
temperature in a dessicator at 8% relative humidity,
otherwise drying conditions can influence gelatin microspheres release of drug.
Fiftee mm diameter vessel, a three blade turbine
rotator of 35 mm in diameter and stirring speed of 750 r.p.m.
was selected, 500mg/batch of gelatin were used and the ratio between gelatin
solution and oil phase was 0.21(v/v)(1,4).
Figure
No. 1 In vitro drug release from microspheres.
Characterization
of Micospheres:
Particle size analysis of gelatin microspheres was
determined using binocular microscope. Surface morphology and particle size of
microspheres were also studied using scanning electron microscopy(5).
Drug
content and drug release measurements of microspheres:
10 mg of gelatin microspheres was milled and immersed
in methanol and stirred for 3 h and then left at room temperature overnight.
Benzophenone-3 was soluble in this medium. The remaining gelatin particles were
separated. Drug Content of this solution was determined using UV
spectrophotometer at 285nm. In vitro drug release from microspheres was
determined in methanol at pH=5.5 (pH was adjusted by using 0.2M NaOH). 2 g of microspheres were placed in 900 ml release
medium in USP paddle type dissolution rate test apparatus, stirring at 40 rpm.
The release medium was maintained at 37±0.2ºC. 5 ml Samples of release medium
were removed at different time intervals and replaced with the same amount of
fresh medium each time(8). Samples were analyzed
spectrophotometrically at 285 nm(6).
Microencapsulation
efficiency:
Drug content or microencapsulation efficiency was
determined as the ratio of actual quantity of drug encapsulated within the
gelatin microspheres to the theoretical quantity of drug added during the
emulsification phase and was expressed as percentage(7) .
Actual Yield
% Entrapment =
* 100
Theoretical Yield
Result
and discussion
Effect of stirring speed – We have tested the effect of stirring speed on particle
size. We modulated the stirring speed and obtained that the drug loaded
microspheres which were cross linked with glucose, and sucrose showed the
particle size 114.8, 96.2, 80.63 and 120.3, 86.3, 40.05µm at 250, 500, and 750
rpm respectively. Whilst drug loaded microspheres which were cross linked with
fructose showed the particle size 104.6, 70.8, 32.6 µm at the same stirring
speed (table no1).
Effect of gelatin concentration – We selected three different concentration i.e 0.75gm, 1.5gm and 3.0gm of gelatin. Drug loaded
microspheres with 0.75gms and 1.5gms gelatin and with two cross linkers
(sucrose and fructose) showed the smooth surface whilst the glucose at same
concentration showed the wavy surface. In contrast drug loaded microspheres
with 3.0gms of gelatin concentration resulted in highly rough surface when
cross linked with all three cross linkers (table no2).
Effect of cross linker - One possible mechanism which is involved in the cross
linking of gelatin is – The aldehyde group of
reducing sugars eg. Glucose or fructose can react
with free amino groups of gelatin molecule resulting in the formation of aminoglycosides. These aminoglycosides
again reacts with another amine group and result in formation of cross linked
structure (table no3 and pg no1) (1, 3, 4).
3.1
Morphology of drug loaded microspheres –
Drug loaded microspheres with all three cross linkers showed good spherical
geometry, and in no case aggregation phenomenon was seen. Micropheres
cross linked with glucose showed wavy surface but cross linker sucrose and
fructose showed smooth surface. All these microspheres were free from
microscopic pores. The particle size of drug loaded microspheres cross linked
with glucose and fructose had almost the same diameter. In contrast microspheres
cross linked with sucrose showed increase in particle size.
3.2
Microencapsulation efficiency – It was
observed that the drug loaded microsphere with sucrose and glucose showed
microencapsulation efficiency of 80% and 92% respectively. But drug loaded microspheres
with fructose showed the 89% microencapsulation efficiency (table no.4)
(8).
3.3
In vitro drug release profile from drug loaded microspheres – The dissolution of drug loaded microspheres both
treated and untreated with cross linking agent was performed at 37ºC in order
to simulate typical conditions of dissolution at body temperature. It was
observed that drug loaded microspheres cross linked with glucose and fructose
resulted in a slower release of drug and t50 and t70 were
increased. Whilst drug loaded microspheres cross linked with sucrose was
dissolved in same fashion as untreated drug loaded microsheres
and t50 and t70 of this microspheres were decreased
(figure no2) (8, 9, 10).
CONCLUSION:
The present study was carried out to
develop sustained drug delivery system for benzophenone
-3 using gelatin as polymer and fructose as cross linking agent. Smooth and
spherical particle were successfully developed by the emulsion cum thermal
gelation technique. Stirring speed 750 rpm was most suitable for smaller size
microsphere preparation. Result demonstrated that glucose and sucrose if used
as crosslinker, larger size of microspheres were
obtained with high and low microencapsulation efficiency respectively while
fructose provides smaller size microspheres with optimum microencapsulation
efficiency. Percentage drug release from
the sucrose cross linked microspheres were faster and same as untreated
microsphere while glucose and fructose cross linked microspheres showed slower
release rate. Hence the microspheres with 750rpm stirring speed, 1.5gms gelatin
as polymer and fructose as a cross linker could be