Submitted by

S.Marimuthu

Reg no: 01108912025

Under the guidance of,

Mr. A. Shanmugarathinam., M.Pharm., (ph.D)LecturerDepartment of pharmaceutical technology,Anna University TiruchirappalliTiruchirappalli-24

FORMULATION AND STUDY OF THE EFFECT OF

FORMULATION VARIABLES ON SUSTAINED RELEASE

CEFUROXIME AXETIL FLOATING MICROSPHERES

INTRODUCTION

Microspheres:

Microspheres are characteristically free flowing powder, ideally having

a particle size less than 200µm and are widely used as a carrier for controlled

release.

Method of preparation:

Single emulsion technique

Double emulsion technique

Polymerization

Spray drying

Solvent evaporation

Flow chart for solvent evaporation method

Drug and polymer dissolved in organic

solvent

Continuous phase with surfactant

Emulsification with aid of surfactant

Evaporation of organic solvent with

the aid of stirring

Filtration and drying

Powdered microspheres

Need of Gastro retention

More often the oral drug absorbtion is unsatisfactory and highly variable between

individuals to individuals, despite excellent Invitro release patterns of the dosage

form

The reason for that, especially variability of gastric transit time in the GI tract.

So the researcheres has involved in the development of gastroretentive dosage forms.

Different techniques for Gastro retention

Floating drug delivery system

Bioadhesive system

High density system

Swelling & expanding system

Floating drug delivery system

In floating drug delivery system, one such approach is floating

microspheres (Hollow microspheres)

Hollow microspheres are low density Spherical particles with out core

that have sufficient buoyancy to float over gastric contents and remain

in stomach for Prolonged period.

Mechanism of hollow microspheres formation

Advantage of floating microspheres

Improves patient compliance

Enhances the bioavailability

Controlled release of drug for prolonged period

Site specific drug delivery to stomach

Reduces the adverse reactions

Superior to single unit floating dosage forms due to no risk of dose dumping

Infectious diseases

0

1

2

3

4

5

6

1

Whooping cough

Tetanus

measules

Malaria

Diarrhea

RespiratoryinfectionRound worm

Tuberculosis

Hepatitis

millions

Global deaths due to infectious diseases

Drug profile

Name : Cefuroxime axetil

Molecular formula : C20H22N4O10S

Molecular weight : 510.48

Pharmacologic class : Second-generation cephalosporin

Therapeutic class : Anti-infective Use: : Treatment of susceptible infections of the upper and lower respiratory tract, otitis media, sepsis, uncomplicated

gonorrhea.

• Mechanism of Action Inhibits bacterial cell wall synthesis

• Protein binding: 33% to 50%

• Bioavailability: Tablet: Fasting: 37%; Following food: 52%

• Half-life elimination: Children: 1-2 hours; Adults: 1-2 hours.

• Dose: 250-500 mg, bid dose

HYPOTHESIS

The drug cefuroxime axetil has low oral bioavailability (37 -52%)

and it prescribed as bid or tid dose because of its short biological half life (1-

2 hrs). The reduced oral bioavailability of drug due to

1. Drug degraded in the intestinal environment.

2. Drug follows saturation absorption kinetics .

So if the drug formulated as a gastroretentive microspheres, the oral

bioavailability of drug can be increased by avoiding the entry of drug in to

the intestine and can increasing the dosing interval of drug by sustained

release microspheres.

OBJECTIVES

• To improve the oral bioavailability of the drug cefuroxime axetil by

preparing gastroretentive microspheres.

• To reduce the dosing frequency of the drug cefuroxime axetil by preparing

sustained release microspheres.

• To characterize the effect of stirring time, continuous phase volume,

dispersing phase volume, and drug to polymer ratio on the properties of

microspheres.

EXPERIMENTAL METHODS

Preformulation studies

Solubility studies:

Cefuroxime axetil:

The drug cefuroxime axetil found to be freely soluble in ethanol,

dichloromethane, acetone and dichloromethane. But the drug cefuroxime

axetil slightly soluble in water.

Ethylcellulose:

The polymer ethylcellulose found to be freely soluble in ethanol,

dichloromethane and chloroform. But it insoluble in water.

Standard Graph for Cefuroxime Axetil in 0.1 N Hcl

Concentration µg/ml

Absorbance

2 0.0905

4 0.1737

6 0.2583

8 0.3435

10 0.4369

COMPATIBILITY STUDIES

FT-IR spectra of cefuroxime axetil pure drug

Spectrum Name: Cefuroxine Axetil pure drug

4000.0 3000 2000 1500 1000 400.0

0.0

10

20

30

40

50

60

70

80

90

100.0

cm-1

%T

3469.20

2947.20

2822.94

1779.191677.68

1595.39

1390.21

1332.45

1245.28

1157.45

1071.34

943.12

873.25

757.52

592.10487.65

FT-IR spectra for Ethyl cellulose polymer

Spectrum Name: Ethil Cellulose.

4000.0 3000 2000 1500 1000 400.0

0.0

10

20

30

40

50

60

70

80

90

100.0

cm-1

%T

3970.96

3430.87

2978.04

2908.17

2130.64

1711.12

1591.39

1374.42

1227.18

1110.55

917.35

879.88

584.78

535.35

FT-IR spectra of mixture of cefuroxime axetil and Ethyl cellulose (1:1)

Spectrum Name: Cefuroxime +Ethyl cellulose.

4000.0 3000 2000 1500 1000 400.0

0.0

10

20

30

40

50

60

70

80

90

100.0

cm-1

%T

3472.16

2979.46

2935.75

2612.59

2369.07

1738.67

1677.66

1597.64 1385.231335.44

1215.44

1070.83

946.26

876.48

759.23

588.62

Comparison of functional group region in the IR- spectrum

Functional

group of drug

Corresponding

region in the

spectrum of

pure drug (cm-)

Corresponding

region in the

spectrum of

drug and polymer

mixer (cm-1)

Limits (cm-1)

C – S (stretch) 592.1 584.78 705 - 570

C = O

(carbonyl)1677.681 1677.66 1760 - 1670

C – N

( stretch)1071.34 1070.83 1090 - 1020

NH - amide 3469.20 3472.16 3500 - 3300

C - C 943.12 946.26 1300 - 700

The spectrum of a mixture of drug and polymer was compared with the

standard spectra of drug and polymer. It could be observed that, very slight

shift in the region which confirms there was no drug and polymer

interaction.

PREPARATION OF MICROSPHERESMicrospheres prepared by solvent evaporation method

Variables used in the microspheres formulations

Materials used F1 F2 F3 F4 F5 F6 F7 F8 F9

Drug: polymer

ratio1: 1.5 1: 1.5 1: 1.5 1: 1.5 1: 1.5 1: 1.5 1: 1.5 1: 1 1: 2

Organic phase

volume (ml)10 10 10 16 5 10 10 10 10

Aqueous phase

volume (ml)50 100 150 100 100 100 100 100 100

Stirring time

(min)30 30 30 30 30 60 90 30 30

Physical characterization of microspheres

1. Percentage yield

Percentage yield = (Weight of microspheres recovered / weight of non

volatile component added) x 100

2. Particle size determination – by optical microscopic method

3. Drug entrapment efficiency [DEE]

DEE = [amount of drug actually present / theoretical drug loaded expected]

x 100.

4. Bulk density

Density = Weight of microspheres taken (gm) / Volume occupied by

microspheres in (ml)

5. Floating behavior of microspheres

Percentage buoyancy = (weight of microspheres floated after time t / Initial

weight of microspheres) x100

6. Morphological study using SEM

7. In-vitro release in 0.1N Hcl

8. In-vitro release kinetic studies

RESULTS

Percentage yield : 68.8 to 82.5%

Drug entrapment efficiency : 60.7 to 75.7%

Mean particle size : 58.52 to 77.36µm

Percentage buoyancy : 62.12 to 81.23%

Bulk density : 0.2610 to 0.5217 gm/ml

In-vitro release : 73.47 % to 89.78%

SEM photographs of microsphere formulation F9

SEM Photograph of formulation F9 at 5000 magnification level

SEM Photograph of formulation F9 at 15000 magnification level

Photographs revealed that, the microspheres were spherical and uneven surfaces. This tendency of the microspheres surface was most probably resulted from the mechanism of solvent evaporation

Discussion

Preparation of microspheres

The Cefuroxime axetil sulfate is a slightly water soluble drug, so aqueous

solution used as a continuous phase in the preparation of microspheres

which reduces the partition of drug in to the continuous phase. Tween 80

used as emulsifying agent which has the HLB value of 15 and is expected

to reduce the interfacial tension between the two immiscible phases.

Solvent combination

In this study mixture of ethanol and dichloromethane used for the

microspheres preparation. Because when non- polar solvent

dichloromethane used alone the polymer get precipitated rapidly at the

time of mixing with water. So to reduce the non- polarity of the

dichloromethane, ethanol was added to that solvent. During microspheres

formation ethanol gets diffused in to the water and dichloromethane was

evaporated.

Effect of continuous phase volume

In microspheres preparation, when the continuous phase volume was

increased from 50 ml to 100 ml and 150 ml

The yield and entrapment efficiency was decreased due to increasing the

partition of drug in to the continuous phase when the continuous phase

volume was increased

Continuous phase volume does not have significant effect on particle size,

floating behavior, and in- vitro release of drug from microspheres.

Formulation code

Continuous phase volume

(ml)Yield (%)

Entrap ment efficiency

(%)

F1 50 77.5 68.2

F2 100 73.5 62.1

F3 150 71.75 60.7

Effect of internal phase volume (organic phase)In microspheres preparation, the volume of Internal phase increased

from 5ml to 10ml and 16ml

Particle size of the microspheres decreased with increasing internal phase volume.

This can be explained as in less amount of solvent, the polymer solution was more

viscous which produce larger droplet when poured in to the continuous phase, so

particle size was increased.

Entrapment efficiency of drug in microspheres was decreased with increasing the

internal phase volume. This may due to the movement of drug particle from

internal phase to continuous phase was increased because of decreasing the

viscosity of drug: polymer solution.

Formulation code

Internal phase

volume (ml)

Entrapment efficiency (%)

Particle size (µm)

F4 5 75.7 77.36F1 10 68.2 70.26F5 15 60.9 69.18

Effect of drug: polymer ratio

In microspheres preparation, when the drug: polymer ratio

increased from 1:1 to 1:1.5 and 1:2

Entrapment efficiency of the drug in microspheres was increased with

increasing drug: polymer ratio because increased polymer amount provides

more binding site for the drug molecules.

Particle size of the microspheres was increased with increasing drug:

polymer ratio. This can be explained as when the drug: polymer ratio was

increased the polymer solution was more viscous which produce larger

droplet when poured in to the continuous phase, so particle size was

increased.

In- vitro drug release was decreased with increasing drug: polymer ratio

due to increasing the diffusional path length for drug molecules

Formulation code

Drug: polymer

ratio

Entrapment efficiency (%)

Particle size (µm)

Percentage of drug release

F8 1:1 62.8 63.94 89.78

F1 1:1.5 68.2 70.26 78.99

F9 1:2 74.2 75.68 73.47

In- vitro dissolution

Among the all of the formulation, formulation F8 shows highest drug

release of 89.78% and formulation F9 shows least drug release of 73.47%.

This may be due to the changes in the drug: polymer concentration

(F8- 1:1, F9- 1:2). Only changes in the drug: polymer ratio has significant

effect on the in- vitro drug release. All other variables has not such effect

on the in –vitro drug release.

In- vitro release kinetics

Regression co-efficient (r2) values for microspheres formulations

Kinetic models

F1 F2 F3 F4 F5 F6 F7 F8 F9

Zero order

0.991 0.954 0.995 0.801 0801 0.757 0.776 0.798 0.861

First order

0.978 0.988 0.929 0.981 0.984 0.978 0.99 0.978 0.983

Hiquchi 0.941 0.979 0.927 0.993 0.992 0.997 0.996 0.995 0.984

Hixson- crowell

0.992 0.987 0.943 0.982 0.984 0.981 0.983 0.972 0.985

n and r2 values from Korsemeyer Peppas model

Formulation code

n- values r2 value Mechanism of release

F1 0.853 0.985Case II or Zero order release, (non- fickian) it refers the dominant mechanism for drug transport is due to polymer matrix relaxation

F2 0.621 0.984Anomalous transport (non- fickian), refers to the coupling of Fickian diffusion and polymer matrix relaxation

F3 0.879 0.991Super case II transport. It refers in addition to diffusion, other release mechanism including matrix erosion and polymer relaxation might be involved

F4 0.514 0.991

Anomalous transport (non- fickian), refers to the coupling of Fickian diffusion and polymer matrix relaxation

F5 0.556 0.995F6 0.498 0.996F7 0.537 0.996F8 0.574 0.991F9 0.534 0.981

Most of the formulations follow Hiquchi release kinetics which indicated

that the release was diffusion controlled and also it shows anomalous

transport (non- fickian) which indicated the coupling of Fickian diffusion

and polymer matrix relaxation.

Conclusion

In this research work attempt was made to increase the bioavailability

of cefuroxime axetil by formulating floating microspheres. Formulation

was successfully made and in –vitro evaluation of floating microspheres

shows encouraging results. By these evaluations following statement

can be concluded

(i) No interaction between the drug and polymer was confirmed.

(ii) The desired yield and entrapment efficiency was obtained.

(iii) It shows good buoyancy over 12 hrs in the acidic medium.

(iv) It provides sustained release of drug over more than 12 hours.

(v) Drug release from microspheres follows coupling mechanism of fickian

diffusion and polymer matrix relaxation.

(vi) The drug: polymer ratio has significant effect on the all characteristics of

microspheres but other variables have effect on only few characteristics of

the microspheres.

THANK YOU