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International Journal of Universal Pharmacy and Bio Sciences 3(3): May-June 2014

INTERNATIONAL JOURNAL OF UNIVERSAL

PHARMACY AND BIO SCIENCES IMPACT FACTOR 1.89***

ICV 5.13*** Pharmaceutical Sciences RESEARCH ARTICLE……!!!

DESIGN & DEVELOPMENT OF GASTRO RETENTIVE FLOATING

MICROSPHERES OF BACLOFEN A Hiren B. Upadhyay, Dr. K. R. Patel, Dr. M. R .Patel

Department of Pharmaceutics, Shri B. M. Shah College of Pharmaceutical Education and Research,

Modasa-383315, Gujarat, India.

KEYWORDS:

Baclofen microsphere;

GRDDS; Floating

system, 32factorial

design.

For Correspondence:

Hiren B. Upadhyay *

Address:

Department of

Pharmaceutics, Shri B.

M. Shah College of

Pharmaceutical Education

and Research, Modasa-

383315, Gujarat, India.

Email:

Hirenupadhyay53@gmail

.com

ABSTRACT

Objectives: Objective of present investigation was to develop baclofen

floating microsphere for retention in the upper part of the GIT to

improve the dissolution in where the solubility of baclofen is more in

acidic medium. Experimental work: Floating Microspheres were

prepared by emulsion solvent evaporation method using Ethyl

cellulose and Eudragit S 100 as polymer and 0.15% w/v span 80 &

liquid paraffin as external medium. 32 full factorial design was used for

optimizing the drug: polymer ratio(X1) and Ethyl cellulose: Eudragit S

100(X2) ratios were selected as independent variables evaluated for

various parameters and analysed using ANOVA and Surface Response

Methodology. Results: Batch F6 was selected as optimized, as

provides desired zero order release profile as well as 79.37%

Buoyancy and 84.08% Entrapment Efficiency, 82.02% yield and mean

particle size of 288.89 μm and spherical microsphere obtained

confirmed by SEM study. Batch F6 remains stable after 30 day

accelerated stability study. Conclusion: Combination of EC and

Eudragit S 100 provides better product compared to EC or Eudragit S

100 alone. Drug and excipients are compatible to each other was

confirmed by FTIR and DSC study.



INTRODUCTION

Oral drug delivery has been known for decades as the most widely utilized route of administration

for delivery of drug via different dosage form due to its ease of administration, high patient

compliance least sterility constraints and flexibility in the design of dosage form.

Gastro retentive system can remain in the gastric region for several hours and hence significantly

prolongs the Gastric Residence Time (GRT) of drug. Prolonged gastric retention improves

bioavailability, reduces drug waste and improves solubility of drug that is less soluble in high ph

environment. It has application also for local drug delivery to the stomach and proximal small

intestine. Gastro retention helps to provide better availability of new products with new therapeutic

possibilities and substantial benefit for patient.

Baclofen is an oral medication that the skeletal muscle, chemically related to gamma-amino butyric

acid (GABA) a naturally occurring neurotransmitter in the brain. It is believed that baclofen, acting

like GABA, blocks the activity of nerves within the part of the brain that control the contraction and

relaxation of skeletal muscle. The evidence suggest the baclofen is transported from gastro intestinal

tract is indicated in long-term treatment of spasticity resulting from multiple -sclerosis and spinal

cord injuries.

Administration of conventional tablet of Baclofen has reported to exhibit fluctuation in plasma drug

concentration leading to fluctuation in plasma concentration, producing side effect such dizziness to

the prescribers. There for release of drug in sustained manner and also requires steady state plasma

concentration. So, formulation of Gastroretentive floating drug delivery satisfies these conditions.

Gastroretentive drug delivery system can be retained in stomach for prolonged time and assist in

increasing sustained delivery of drug delivery like Gas generating system, Raft forming system,

Hydro dynamically balanced system, Low density system, High density system and Bio adhesive

system.

Hence objective of study to formulate floating microspheres of Baclofen to improve bioavailability

and also get steady state plasma concentration.

MATERIAL

Baclofen from Intas Healthcare Pvt. Ltd., Ahmedabad, Ethocel (Ethyl cellulose 20 cps) from

Colorcon Asia Pvt. Ltd., Goa. Eudragit S100 from Evonik degusa india Pvt ltd., Mumbai, Liquid

paraffin from Finar Chemical Ltd Ahmedabad, India, Tween 80 from S. D. Fine Chemicals Ltd.,

Mumbai, India, Ethanol from Finar Chemical Ltd Ahmedabad, India, Dichloromethane form Finar

Chemical Ltd Ahmedabad, India.



Method

Microspheres were prepared by Emulsion solvent evaporation method. Baclofen and Different

polymer with drug to polymer ratio (1:1, 1:2, 1:3, 1:4) are dissolved in organic solvent like

Dichloromethane : Ethanol (1:1) to get dispersed phase in non polar Liquid paraffin containing Span

80 (0.15%w/w)as droplet stabilizer and stirred at 1200 rpm for 3 hr. During this time solvent was

completely removed by evaporation. The solidified microspheres were filtered, washed five times

with 20 ml petroleum ether, dried under vaccum at a room temperature for 12 hr.

Selection of polymer

Review of literature reveals EC and Eudragit®

S 100 is most widely used encapsulating polymer

because of its compatibility and multi-functionality, in present study, Ethocel 20 cps and Eudragit®

S100 is selected as polymer and various batches of microsphere prepared using single and

combination of polymer.

Characterization of microspheres

A) Scanning Electron Microscopy and Morphology Characterisation22

The surface morphology and internal texture of the microspheres were studied by scanning electron

microscopy. Scanning Electron Microscope (JSM 5610 LV SEM, JEOL, Datum Ltd, Tokyo, Japan)

Acceleration voltage set at 15 kV at Magnification level 200x, 100x, 70x.The samples were then

randomly scanned and microphotographs were taken on different magnification. Then

morphological characteristics of microspheres were determined from photograph of SEM.

B) % Production Yield 23

The percentage yield of microspheres of various formulations was calculated using the weight of

final product after drying with respect to the initial total weight of the drug and polymer used for

preparation of microspheres. The percentage yields were calculated as per the formula mentioned

below.

% Production Yield = Total mass of microsphere/total mass of raw materials× 100

C) Determination of mean particle size 21

The particle size was measured using an optical microscope, and the mean particle size was

calculated by measuring 100 particles with the help of calibrated ocular micrometer. The slide

containing microspheres was mounted on the stage of the microscope and diameter of at least 100

particles was measured using a calibrated optical micrometer.

D) % Drug loading: 11

To determine the % drug loading, 20 mg microspheres were thoroughly triturated and dissolved in

minimum amount of methanol. The resulting solution was made up to 100 ml with 0.1 N HCl and



filtered. Drug content was analyzed spectrophotometrically at 219 nm. The percentage incorporation

efficiency and percentage drug loading were calculated using eq. given below.

% Drug loading = Actual drug present / Weight of microsphere taken for analysis x 100

E) Entrapment Efficiency: 16

To determine the % Entrapment Efficiency 20mg microspheres were crushed in a glass mortar and

dissolved in minimum amount of methanol. The resulting solution was made up to 100 ml with 0.1

N HCl and filtered and analyzed spectrophotometrically at 219 nm.

% Entrapment Efficiency = Actual drug content / Theoretical drug content x 100

F) In-vitro buoyancy18

Floating behaviour of hollow microspheres was studied using a USP dissolution test apparatus ΙΙ.

The microsphere (50 mg) was spread on 900 ml of 0.1 N HCl . The medium was agitated with a

paddle rotating at 100 rpm and maintained at 37̊ C. After12 hr. Both the floating and settled portion

of microspheres was collected separately. The microspheres were dried and weighed and the

percentage of floating microspheres was calculated.

Buoyancy (%) = Wf /Wf + Ws

Where, Wf and Ws are the weights of the floating and settled microspheres.

G) Density 8

The bulk density (BD) and tapped density (TD) of microspheres were determined. Two grams of

microspheres was introduced into a 10 ml calibrated measuring cylinder. After noting down the

initial volume, the cylinder was allowed to fall under its own weight onto a hard surface from the

height of 2.5 inch at 2 second intervals. The tapping was continued until no further change in volume

was noted. BD and TD were calculated using following equations:

BD = Weight of Powder / Volume of Packaging

TD=Weight of Powder / Volume of Packaging after tapping

H) Hausner’s ratio

Hausner‟s ratio of the microspheres was calculated by using following formula:

Hausner‟s ratio= Tapped Density / Bulk Density

I) Carr’s index

The Carr‟s index of microspheres was determined by following equation

Carr‟s Index = Tapped Density - Bulk Density/ Tapped Density x100

K) Angle of repose

The angle of repose was determined by the fixed funnel method. The accurately weighed powders

were taken in a funnel. The height of funnel was adjusted in such a way that the tip of the funnel just



touched the apex of the head of the powder. The powder was allowed to flow through the funnel

freely onto the surface. The diameter of the powder cone was measured. The angle of repose was

calculated using the following equation.

Angle of Repose = tan-1

h/r

Where, h = Height of the powder blend cone

r = Radius of the powder blend cone

L) In-vitro drug release 13

Weighed microspheres equivalent to 30 mg of Baclofen were taken and filled in capsule (size No.0)

and subjected to dissolution test in USP XXΙΙΙ dissolution test apparatus using paddle method . The

dissolution media was 900 ml of HCl buffer pH 1.2 maintained at 37± 0.5̊ C and rotated at 50 rpm.

Sample (5 ml) were withdrawn at specified time intervals and replaced with the same volume of

fresh medium, filtered, suitably diluted and analyzed at 219 nm.

Kinetic model for release data (12-15)

The drug released data of all batches were fitted with desired kinetic model such as Zero order

kinetic, First order kinetic, Higuchi model and Korsemeyer peppas model to ascertain the drug

release. The Zero order and First order drug release. The Zero order and First order drug release

explain the drug release depend on drug concentration or not. The Korsemeyer peppas model

described the method of drug release and Higuchi model described the diffusional drug release.

Zero order = Q1 = Q0 + K0t

First order = Qt = Q0e-K1t

Higuchi model = m= (100-q) ×t1/2

Hixon Crowell Model = W01/3

– Wt1/3

= kt

Korsemeyer peppas model = Mt/Mα = K × t n

Where Q1 is the amount of drug dissolved in time t, Q0 is the initial amount of drug in the solution,

Qt is the amount of drug dissolved in time t, W0 is initial amount of drug in dosage form, Wt is

remaining amount of drug in dosage form at time t, Mt/Mα is the fraction of drug release at time t

and n is diffusion exponent. K0, K1, and k refer to the rate constant.

Statistical analysis

The statistical analysis of the factorial design batches was performed by multiple regression analysis

using Microsoft Excel. Data obtained from all formulations were analyzed using statistica software

and used to generate the study design and the response surface plots. Polynomial models were

generated for all the response variables using Microsoft Excel. In addition analysis of variance

(ANOVA) was used to identify significant effects of factors on response regression coefficients. The

F value and p values were also calculated using Microsoft Excel. The relationship between the

dependent and independent variables was further elucidated using response surface plots.



Similarity factor (f2) 16-17

To evaluate and comparison of dissolution profiles, the dissolution profiles were analyzed using

similarity factor f2. The f2 value between 50 and 100 suggests that the dissolution profiles are similar.

Dissimilarity factor (f1) 16-17

The dissimilarity factor (f1) calculates the percent difference between the two curves at each time

point and is a measurement of the relative error between the two curves. The values should lie

between 0-15.

Accelerated stability study 18

The purpose of stability testing is to provide evidence on how the quality of drug substance or drug

product varies with time under the influence of a variety of environmental factors such as

temperature, humidity, and light, and to establish a re-test for the drug substance or a shelf life for

the drug product and recommended storage condition. The storage condition used for stability

studies were accelerated condition (400 C ± 2

0 C / 75 % ± 5% RH). Stability study was carried out

for the optimized formulations. Tablets of optimized formulation were striped packed and kept in

humidity chamber on above mention temperature.

Preliminary trial batches

Table 1: Preliminary trial batches

Formulation code Polymer used Drug : Polymer ratio

B 1

Ethyl cellulose

1:1

B 2 1:2

B 3 1:3

B 4 1:4

B 5

Eudragit S 100

1:1

B 6 1:2

B 7 1:3

B 8 1:4

B 9 Ethyl cellulose : Eudragit

S 100(1:1)

1:4



Table 2: Preliminary batches composition

Ingredient Formulation code

B 1 B 2 B 3 B 4 B 5 B 6 B 7 B 8 B 9

BACLOFEN 250 250 250 250 250 250 250 250 250

EC 250 500 750 1000 - - - - 500

EUDRAGIT

S100

- - - - 250 500 750 1000 500

DCM 10 10 10 10 10 10 10 10 10

ETHANOL 10 10 10 10 10 10 10 10 10

Tween

80%w/w

0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15

Figure 1: FT-IR spectra of pure drug Baclofen

Table 3: Selection of independent variables, dependent variables

32 Full Factorial Designs

Independent Variables Dependent Variables

X1 X2 Y

Drug : Polymer Ratio Ethocel : Eudragit®

S

100

Drug Entrapment Efficiency,

% Drug loading,

% Drug Release at 2 hour

5007501250175022502750325037501/cm

0

10

20

30

40

50

60

70

80

90%T

2983

.98

2845

.10

2750

.58

2690

.79

2569

.27

2569

.27

2324

.30

2158

.42

1627

.97

1627

.97

baclofen



Table 4: Selection of levels for independent variables

Coded value Drug : Polymer ratio Ethocel : Eudragit® S 100

-1 1:3 75:25

0 1:4 50:50

1 1:5 25:75

Table 5: 32 factorial design layout

Batch

Code

Coded Value Actual value

Drug :

polymer

ratio

Ethocel :

Eudragit® S 100

Drug :

polymer

ratio

Ethocel : Eudragit®

S 100

F1

-1 -1 1:3 75:25

F2 0 -1 1:4 75:25

F3 1 -1 1:5 75:25

F4 -1 0 1:3 50:50

F5 0 0 1:4 50:50

F6 1 0 1:5 50:50

F7 -1 1 1:3 25:75

F8 0 1 1:4 25:75 F9 1 1 1:5 25:75

Table 6: Formulation of 32 factorial designs bathes

Formulation code Baclofen(gm) Ethocel

(gm)

Eudragit S 100 (gm)

F1 0.5 1.125 0.375

F2 0.5 1.500 0.500

F3 0.5 1.875 0.625

F4 0.5 0.750 0.750

F5 0.5 1.000 1.000

F6 0.5 1.250 1.250

F7 0.5 0.375 1.125

F8 0.5 0.5 1.5

F9 0.5 0.625 1.825



Table 7: Results of % Production Yield of preliminary batches

Batch No. Theoretical

Yield

Practical

Yield

%Practical

Yield

Product

characteristic

B1 500 410 82.00% Not spherical

B2 750 635 84.66% Nearly spherical

B3 1000 854 85.4% Spherical

B4 1250 1120 89.60% Spherical

B5 500 395 79.00% Not spherical

B6 750 610 81.33% Nearly spherical

B7 1000 821 82.10% Spherical

B8 1250 1050 84.00% Spherical

B9 1250 1155 92.4% Spherical

Table 8: Result of % Drug loading and Entrapment efficiency

Batch

No.

%Drug

Loading

Entrapment efficiency

Theoretical

Drug content

Actual drug

content (n=3)

% EE

B1 47.50 10 9.5±0.02 95

B2 30.1 6.66 6.02±0.05 90.39

B3 19.6 5 3.92±0.04 78.4

B4 16.0 4 3.20±0.01 80.00

B5 46.5 10 9.3±0.03 93

B6 29.5 6.66 5.9±0.02 88.58

B7 18.00 5 3.60±0.01 72.00

B8 15.6 4 3.12±0.03 78.00

B9 17.2 4 3.45±0.01 86.25

Table 9: Results of % Buoyancy

Batch no. % Buoyancy

B1 82 %

B2 75 %

B3 84.1 %

B4 82.6 %

B5 83.5 %

B6 80.7 %

B7 79.9 %

B8 76.14 %

B9 92.97 %



Table 10: Results of mean particle size analysis

Batch No. Mean particle size (µm)

B1 209.76

B2 223.43

B3 241.24

B4 267.85

B5 201.67

B6 232.59

B7 247.86

B8 278.07

B9 303.75

Figure 2: SEM formulation F6 at 70X magnification





Table 11: Micromeritic properties of of factorial batches F1-F9

Batch

code

Bulk density

(g/cm3)

Tapped

density

(g/cm3)

Hausner’s

ratio

Carr’s index

(%)

Angle of

repose(θ)

F1 0.364 0.421 1.15 13.53 21.69

F2 0.379 0.435 1.14 12.87 21.45

F3 0.416 0.473 1.13 12.05 22.65

F4 0.437 0.504 1.15 13.29 24.30

F5 0.449 0.53 1.18 15.28 24.85

F6 0.463 0.531 1.14 12.80 26.56

F7 0.481 0.563 1.17 14.56 28.57

F8 0.458 0.547 1.19 16.27 29.89

F9 0.463 0.558 1.20 17.02 29.08

Table 12: Particle size of factorial batches F1-F9

Batch code Particle size (μm)

F1 275.75

F2 278.98

F3 279.43

F4 273.67

F5 276.04

F6 288.89

F7 272.75

F8 276.45

F9 268.32

Table 13: Results of %yield of factorial batches F1-F9

Batch code % Yield

F1 80.59

F2 88.82

F3 89.68

F4 81.35

F5 82.87

F6 82.02

F7 75.66

F8 78.35

F9 79.03



Table 14:%Drug loading and Entrapment Efficiency of factorial batches F1-F9

Batch

no.

%Drug

loading

Entrapment efficiency (EE)

Theoretical drug

content/20 mg of

microsphere in mg

Actual drug content/20

mg of microsphere in

mg n=3

EE

F1

F2

F3

F4

F5

F6

F7

F8

F9

19%

15.55%

13.25%

19.25%

16%

14.45%

20.30%

16.60%

14.75%

5

4

3.33

5

4

3.33

5

4

3.33

3.80 ±0.02

3.11±0.01

2.65±0.03

3.85±0.02

3.20±0.01

2.89±0.02

4.06±0.04

3.32±0.03

2.95±0.05

76%

77.75%

79.57%

77.00%

80.00%

84.08%

81.2%

83%

88.58%

Table 15: %Buoyancy of factorial batches F1-F9

Batch no. %Buoyancy

F1 80.15

F2 82.72

F3 83.15

F4 73.88

F5 77.16

F6 79.37

F7 71.39

F8 74.88

F9 78.53

Table 16: Formulation and Evaluation of Batches in 32 factorial Design

Batc

h

Cod

e

Variable

Levels in

Coded Form

DL EE Q2 n K

X1 X2

F1 -1 -1 19 76 47.41 0.405 0.373

F2 0 -1 15.55 77.57 41.62 0.495 0.293

F3 1 -1 13.25 79.57 29.38 0.593 0.206

F4 -1 0 19.25 77 56.35 0.279 0.471

F5 0 0 16 80 53.52 0.299 0.438

F6 1 0 14.45 84.08 42.40 0.447 0.309

F7 -1 1 20.30 81.2 63.50 0.325 0.515

F8 0 1 16.60 83 49.09 0.395 0.375

F9 1 1 14.75 88.58 43.43 0.407 0.336

Coded

Values

Actual Values

X1 X2

-1 1:3 75:25

0 1:4 50:50

1 1:5 25:75



Table 17: Result of regression analysis of factorial design batches

% Drug Loading

Response b0 b1 b2 b11 b22 b12

FM 16.044 -2.68 0.6416 0.7833 0.0083 0.05

P=6.51E-06 P=0.0002 P=0.014 P=0.037 P=0.9719 P=0.7673

RM 16.05 -2.683 0.6416 0.7833 - -

Entrapment efficiency


FM 80.03 2.67 3.57 0.4883 0.3233 1.4525

P=3.81E-06 P=0.014 P=0.006 P=0.629 P=0.7461 P=0.1094

RM 80.575 2.6716 3.5766 - - -

FM= Full model, RM= Reduced model

Q2


FM 51.42 -8.67 6.268 -0.998 -5.018 -0.51

P=0.0002 P=0.0093 P=0.022 P=7175 P=0.1395 P=0.79

RM 47.411 -8.675 6.268 - - -

N


FM 0.333 0.0728 -0.061 -0.012 0.094 -0.026

P=0.0008 P=0.012 P=0.020 P=0.6284 P=0.0274 P=0.21

RM 0.3422 0.0728 -0.0602 - 0.0949 -

K


FM 0.4070 -0.0847 0.0589 -0.00066 0.0564 -0.00318

P=0.0004 P=0.0080 P=0.0219 P=0.9790 P=0.0936 P=0.8591

RM 0.3690 -0.0845 0.0589 - - -

FM= Full model, RM= Reduced model



Table 18: Result of ANOVA (regression analysis) of factorial design batches for selected

responses

.

Q2

DF SS MS F R2 Significance F

Regression

FM

RM

Error

FM

RM

5

2

3

6

738.70

687.28

37.8246

91.2554

148.13

343.64

12.60

15.20

18.54

22.59

0.9488

0.8827

0.018307

0.0016274

Fcalc.= 1.72

Fcritical=9.27

DF(3,3)

N


Regression

FM

RM

Error

FM

RM

5

3

3

5

0.07546

0.072255

0.003364

0.006409

0.01529

0.024085

0.00112

0.00123

13.57

18.7796

0.9576

0.9184

0.02843

0.003786

Fcalc.= 1.38

Fcritical=9.55

DF(2,3)

K


Regression

FM

RM

Error

FM

RM

5

2

3

6

0.070376

0.06396

0.003215

0.009664

0.01407

0.0319

0.001083

0.001611

12.999

19.8563

0.9558

0.8687

-

0.0307453

0.0022526

Fcalc.=1.97

Fcritical=9.2766

DF (3,3)

% Drug Loading


Regression

FM

RM

Error

FM

RM

5

3

3

5

46.9094

46.8993

0.2861

02962

9.381

15.6374

0.09532

0.05922

98.37

263.84

-

-

0.9939

0.9937

0.0015

6.35E-06

Fcalc.= 1.60

Fcritical=9.55

DF(2,3)

% EE


Regression

FM

RM

Error

FM

RM

5

3

3

5

128.70

119.58

4.9816

14.1067

25.7486

59.7907

1.6605

2.3511

15.5086

25.4364

-

0.9627

0.8944

-

0.02860

0.001175

Fcalc.= 7.49

Fcritical=9.55

DF(2,3)



RESULT AND DISCUSSION

Drug excipients compatibility study:

Fourier transform infrared spectroscopy has been used to study the physical and chemical

interactions between drug and the excipients used. Fourier transform infrared (FTIR) spectra of

Baclofen, Ethocel 20 cps, Eudragit S 100 and physical mixture of Baclofen, Eudragit S 100 and

Ethocel 20 cps was recorded using KBr mixing method on FTIR instrument (FTIR-8400S,

Shimadzu, Kyoto, Japan).

% Practical Yield of preliminary batches

The percentage yields of microspheres of all the formulation was in the range of 79 % to 92.4%.

% Buoyancy of preliminary batches

From the result it can be observed that highest % Buoyancy observed for batch B9, B1, B3, B4 and

B5 so it can be concluded that combination of polymer Ethyl cellulose and Eudragit S100 impart

highest % buoyancy.

Mean Particle size of preliminary batches

The Mean Particle size of all the batches was found to be ranging between 201.67-303.75 µm. As

drug: Polymer concentration increase mean particle size increase as shown in (table 10).

In-Vitro drug release studies of preliminary batches

Figure 5: In-vitro drug release studies of preliminary batches n=3, SD±0.47

Scanning Electron Microscopy and Morphology Characterization of factorial design batches:

Spherical microspheres formed during the solvent evaporation diffusion process could be evidently

seen from photographs of SEM. Inward dents were seen on the surface, probably due to collapse of

the walls of the microspheres during the in situ drying process. Thus, removal of the solvent from

the embryonic microspheres influences the morphology of the product. The microspheres were

rough and grossly spherical and slightly aggregated and shows few pores on surface, due to the rapid

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14

C

P

R

TIME IN HOUR

B1

B2

B3

B4

B5

B6

B7

B8

B9



escape of the volatile solvents during formulation. Very less particulate matter of the drug and

polymer were seen on the surface of the microspheres, indicating uniform distribution of the drug in

the polymeric network.

Micromeritic properties of floating microspheres of factorial design batches:

The evaluation was carried out were bulk density, tapped density, Hausner‟s ratio, Carr‟s index, and

angle of repose as per procedure described in Preformulation study.

The angle of repose of formulations of the microspheres ranged from 21.45° to 29.89° (Table-). The

bulk and tapped density values of formulations of the microspheres ranged from 0.364 to 0.481

g/cm3 and 0.421 to 0.563 g/cm

3 respectively. The % compressibility index (Carr‟s index) ranged

between 12.05% and 17.02%. The values of Carr‟s index and the angle of repose indicate excellent

flow properties. Obviously the density values of the floating microspheres (</1.000 g/cm3) were less

than that of the gastric fluid (~/1.004 g/cm3), thereby, implying that these microcapsules will exhibit

an excellent buoyancy effect in vivo. Also, Hausner‟s ratio found 1.13-1.20 that indicates greater

cohesion between particles. The better flow property indicates that the floating microspheres

produced are unaggregated. Thus, it is an added advantage while processing the formulation using

high-speed packaging equipments.

Average Particle size of factorial design batches:

The effect of polymer concentration on the particle size of the microspheres was determined. The

mean particle size of the microspheres found in the range of 272.75-288.89μm. Although polymer

Ethyl cellulose and Eudragit S 100 affects the particle size, it was noted that particle size increased

with the increasing Ethyl cellulose concentration and a minor decrease in the particle size observed

in the batches prepared using higher amount of Eudragit S 100 (Table-5.9). The viscosity of the

medium increases at a higher Ethyl cellulose concentration resulting in enhanced interfacial tension.

Also noted that mean particle size of the microspheres decreased with increasing Eudragit S 100

concentration.

% Yield of factorial design batches:

Effect of polymer concentration on the percentage yield of the resulting microspheres observed,

formulations were prepared at varying concentrations of Ethyl cellulose and Eudragit S 100. The

yield of the resulting microspheres increased with increasing concentration of Ethyl cellulose (batch

F1-F3) and slight decrease in the %yield observed with increase in the concentration of Eudragit S

100.



% Drug loading and Entrapment Efficiency of factorial design batches:

The drug loading of microspheres varied from 13.25% to 20.30% and the drug entrapment efficiency

of microspheres varied from 76% to 88.58% (Table-14). Results demonstrated that as the drug:

polymer ratio increases, there is decrease in drug loading of the microspheres was noted. Polymer

Ethyl cellulose and Eudragit S 100 does not influence drug loading of the microsphere although

entrapment efficiency is affected by Ethyl cellulose: Eudragit S 100 ratio. Increase in the entrapment

efficiency is observed as the amount of Ethyl cellulose decrease and Eudragit S 100 increase in

formulation. It was noted that entrapment efficiency is not significantly affected by Drug: Polymer

ratio but affected by the Ethyl cellulose: Eudragit S 100 ratio and concluded that Eudragit S 100 is

more efficient polymer for encapsulating the drug in the microsphere.

%Buoyancy of factorial design batches:

It is floating ability test to investigate the total floating time of the prepared microspheres. The

microspheres were spread over the surface of simulated gastric fluid (SGF) and the fraction of the

microspheres settling as a function of time was quantified. It should be noted that the situation in

vivo can be quite different and the residence time may vary widely depending on the phase of gastric

motility. The microspheres containing more Ethyl cellulose compared to Eudragit S 100 showed

good floating ability and conclusion made that EC being insoluble and unswellable remained floated,

whereas Eudragit S100 swelled and eroded with time. The results also showed a tendency that larger

the particle size more the buoyancy.

In vitro drug release study of factorial design batches:

From the results of the dissolution study, it was concluded that formulation F1, F4, and F7

containing lowest Drug: Polymer ratio showed 96% ~100% drug release in 10 hours. For

formulations F2, F5, and F8, the drug release was 94.24%–96.76% within 10 hours and F5 shows

96.95% drug release in 12 hours. Formulations F3, F6, and F9 showed 94.25%–100.56% of drug

release at 12 hour. Important conclusion drawn that Drug present on the surface was responsible for

the „burst effect‟ or „burst release‟ in initial time or at first hour after administration of dosage form.

As Drug: Polymer ratio increases, further retardation in drug release observed. Another observation

made is that when concentration of Eudragit S 100 among two polymer increases then more release

of drug observed (F7-F9) compared to those batches containing less amount of Eudragit S 100 (F1-

F3). Moreover, from the results it is also clear that no burst effect was seen and drug release was

significantly sustained. It was observed that as the concentration of EC increased, %cumulative

release of Baclofen from microsphere decreased and as the concentration of Eudragit S 100 increases



in formulation, increase in the %cumulative release observed. Among nine batches, one batch to be

is selected as optimized batch after calculating the similarity factor for dissolution test.

Figure 5: Graph of in vitro drug release study of factorial batches F1-F3

Figure 6: Graph of in vitro drug release study of factorial batches F4-F6

Figure 7: Graphs of in vitro drug release study of factorial batches F7-F9

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14

f1

f2

f3

C

P

R

TIME IN HOUR

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14

F4

F5

F6

C

P

R

TIME IN HOUR

0

20

40

60

80

100

120

0 2 4 6 8 10 12 14

F7

F8

F9

C

P

R

TIME IN HOUR



Full and Reduced Model for Q2

Full model

Y = 51.4238 - 8.67839 (X1) + 6.26833345 (X2) -0.51724432 (X12)

-0.998346 (X1)2 – 5.01864 (X2)

2

Reduced model Y = 47.41132 -8.67635 (X1) +6.26853(X2)

Figure 8: Response surface plot of Q2

From the surface plot of Q2 (drug release from microsphere at 2 hour) it can be concluded that as X1

(drug: polymer ratio) increases drug release decreases and as X2 (EC: Eudragit S 100 ratio)

increases i.e. as amount of EC compared to Eudragit S increases then drug release also increases

from microsphere. 3D surface plot of Q2 clearly indicate effect of both parameters, on the drug

release as discussed above.

Full and Reduced Model for Release Rate Constant (k)

Full model Y = 0.4070567757 - 0.0847635842 (X1) + 0.0589159296 (X2)

- 0.0031867 (X12) -0.00066517 (X1) 2

- 0.05643194(X2) 2

Reduced model Y = 0.3690172527- 0.084379546(X1) + 0.0589566896(X2)

Figure 9: Response surface plot of k



From the surface plot of release rate constant (k) it can be concluded that as X1 (drug: polymer ratio)

increases, release rate constant (k) decrease and as X2 (EC: Eudragit S 100 ratio) increases i.e. as

amount of EC compared to Eudragit S increases then release rate constant (k) increases.

Full and Reduced Model for diffusion co-efficient (n)

Full model Y = 0.333471270 + 0.07281940 (X1) - 0.0639259 (X2)

- 0.0268896 (X12) + 0.0124897 (X1) 2

+ 0.0949742 (X2) 2

Reduced model Y = 0.342246968 + 0.072852503 (X1) - 0.06090915(X2)

+0.094949203(X2) 2

Figure 9: Response surface plot of n

From the surface plot of diffusion exponent (n) it can be concluded that as X1 (drug: polymer ratio)

increases, diffusion exponent (n) increases and as X2 (EC: Eudragit S 100 ratio) increases then

diffusion exponent (n) decrease.

Full and Reduced Model for % Drug loading

Full model Y = 16.044176249 - 2.680461504 (X1) + 0.641633835 (X2)

+ 0.05789639 (X12) + 0.7823946 (X1) 2 +0.0083138 (X2)

2

Reduced model Y = 16.05639724 - 2.683131504 (X1) + 0.616633235(X2)

+ 0.781297464(X1) 2



Figure 10: Response surface plot of % Drug Loading

From the surface plot of %drug loading, it can be concluded that as X1 (drug: polymer ratio)

increases, %drug loading decreases and as X2 (EC: Eudragit S 100 ratio) increases i.e. as amount of

EC compared to Eudragit S increases then %drug loading also increases in microsphere.

Full and Reduced Model for % Entrapment efficiency

Full model Y = 80.34743771 + 2.672416756 (X1) + 3.574181964 (X2)

+ 1.4552303 (X12) +0.488312802 (X1) 2 + 0.32339139 (X2)

2

Reduced model Y = 80.57583631+ 2.67167564 (X1) + 3.576619641 (X2)

Figure 11: Response surface plot of % Entrapment Efficiency

From the surface plot of entrapment efficiency it can be concluded that as X1 (drug: polymer ratio)

increases, entrapment efficiency increases and as X2 (EC: Eudragit S 100 ratio) increases i.e. as

amount of EC compared to Eudragit S increases then entrapment efficiency also increases.



Result of kinetic modeling of dissolution data

Table 19: kinetic treatment of dissolution data

The kinetics of the dissolution data were well fitted to zero order, Higuchi model and Krosemeyer-

Peppas model as evident from regression coefficients (table 9)

F1 F2 F3 F4 F5 F6 F7 F8 F9

Zero order

B 7.212 6.740 7.196 5.016 4.552 5.811 7.076 6.052 5.738

A 32.98 28.14 14.98 45.85 44.41 30.77 49.349 36.985 31.959

R2 0.996 0.990 0.976 0.994 0.996 0.993 0.979 0.996 0.996

First order

B 0.046 0.047 0.056 0.030 0.027 0.039 0.039 0.038 0.037

A 1.587 1.52 1.38 1.69 1.67 1.55 1.72 1.61 1.57

R2 0.994 0.967 0.965 0.992 0.988 0.971 0.966 0.976 0.988

Higuchi

B 29.04 30.11 32.70 21.14 20.89 26.82 27.79 26.92 26.07

A 6.744 -2.006 -17.96 25.94 23.09 3.16 24.54 10.18 5.71

R2 0.981 0.994 0.961 0.980 0.990 0.993 0.987 0.993 0.980

Hixon Crowell

B -2.404 -2.246 -2.398 -1.672 -1.517 -1.937 -2.358 -2.017 -1.912

A 22.33 23.95 28.33 18.04 18.52 23.07 16.88 21.00 22.68

R2 -0.996 -0.990 -0.976 -0.994 -0.996 -0.993 -0.997 -0.993 -0.996

Korsmeyer and Peppas

A -0.428 -0.531 -0.685 -0.326 -0.357 -0.509 -0.287 -0.425 -0.473

n 0.405 0.495 0.598 0.279 0.299 0.447 0.325 0.395 0.407

R2 0.978 0.991 0.935 0.964 0.973 0.990 0.985 0.984 0.975

B = slope, A= intercept, n= diffusion exponent R2= Square of corr. coefficient,

Comparison of dissolution profiles for selection of optimum batch

Table 20: Dissimilarity factor (f1) and Similarity Factor (f2) for F1-F9

Batch dissimilarity factor (f1) Similarity factor (f2)

F1 23.73 44.50

F2 10.417 57.71

F3 8.36 57.90

F4 24.56 42.11

F5 14.42 49.21

F6 5.74 68.44

F7 54.19 28.32

F8 18.01 47.99

F9 6.11 66.21



Result of accelerated stability study

Table 21: Parameters of Batch F6 after Accelerated Stability Study

Parameters Zero time After 30 day

%Drug loading 14.45% 14.03%

Entrapment efficiency 84.08% 83.33%

%Buoyancy 79.37% 75.54%

Comparison of dissolution profile at initial time

Similarity Factor (f2) 96.6861

Dissimilarity Factor

(f1)

0.5640

CONCLUSION:

The present study was reported that the development of Baclofen-loaded floating micro-particulate

system by an Emulsion solvent evaporation method. From the preliminary trials, combination of

biocompatible and cost-effective encapsulating polymers ethyl cellulose and Eudragit S 100 selected

as it provides better results compared to EC and Eudragit S 100 alone when evaluated for Drug

loading, entrapment efficiency, yield and buoyancy.

32 full factorial design used for optimization, variables shows the significant effect on microsphere

formulation. The particle size analysis revealed microsphere size range of 272.75-288.89μm and

scanning electron microscopic studies shows spherical shape of microsphere. Response obtained

were evaluated statistically using ANOVA model and Regression analysis, statistics results found to

be significant and concluded that Formulation F6 prepared with 1:5 drug: polymer ratio and EC:

Eudragit S 100(50:50) was found to be the optimized as microspheres exhibited good encapsulation

efficiencies, excellent floating and micromeritic properties for formulating as single-unit dosage

forms like microsphere filled hard gelatin capsule. The microspheres were having lower densities

thus; such floating microspheres of baclofen can be used for prolonged gastric residence of the drug

and improves dissolution in stomach. In vitro drug release data showed that optimized formulations

released baclofen in a controlled manner for 12 h. Drug release kinetics fitted best with zero order,

Higuchi model and korsemeyer peppas equation based on the highest n values. The mechanism of

drug release of Microspheres showed fickian diffusion bared mixed order (anomalous) with zero

order drug release dominant. Formulation F6 seen to be stable after 30 days of accelerated stability

study.

Finally concluded that Baclofen floating microsphere are better promising alternative to

conventional oral drug delivery system for the treatment of patients suffering from spasticity.



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