Topical Anti-Inflammatory Gels of Fluocinolone Acetonide Entrapped in Eudragit Based Microsponge Delivery System

 

John I D’souza*and Harinath N More

Bharati Vidyapeeth College of Pharmacy, Near Chitranagari, Kolhapur 416 013, M.S., India

*Corresponding Author E-mail:  johnsir4u@gmail.com

 

ABSTRACT

Fluocinolone acetonide (FA) is a corticosteroid primarily used in dermatology to reduce skin inflammation and relieve itching. The percutaneous absorption increases risk associated with systemic absorption of topically applied formulation. Controlled release of drug to the skin could reduce the side effect while reducing percutaneous absorption. Therefore, the aim of the present study was to produce FA entrapped microporous microparticles (microsponges) to control the release of drug to the skin. Microsponges were prepared by previously optimized quasi-emulsion solvent diffusion method.   Compatibility of drug with reaction adjuncts was studied by FT-IR and DSC. Production yield, loading efficiency and particle size analysis and surface morphology of microsponges were performed. Microparticles were then carbopol 934 gels into standard vehicles for release and comparative anti-inflammatory studies. Free flowing powder microsponges were spherical in shape, between 31.34 and 82.26 μm in diameter. FT-IR and DSC studies revealed absence of primary incompatibility between formulation adjuvants and process parameters. Surface morphology by scanning electron microscopy revealed micro-porous nature of microsponges. Drug release was observed controlled with comparative anti-inflammatory activity with the gels containing free drug.

 

KEY WORDS                                 Microsponges, Eudragit RS 100, anti-inflammatory, Fluocinolone acetonide

 


 

INTRODUCTION:

The human skin is a large and complex organ that protects and fosters the biological functions it encloses. As the interface between the organism and the external world, the skin is susceptible to injuries from the environment or from other organisms. 1 Hence, skin inflammatory diseases are very frequent though they are usually transitory and do not cause serious damage. However, some peculiar skin diseases are chronic and can decrease the quality of the patient’s life. Some of these conditions include atopic dermatitis, eczema and psoriasis which affect around 2% of the world population. 2 These diseases can be treated either topically or systemically with glucocorticoids, immuno-suppressors and more recently, with monoclonal antibodies and recombinant cytokines. 3 Atopic dermatitis is the most common inflammatory skin disorder of children, affecting as many as 10% to 20% of the childhood population.4-6 Corticosteroids are considered the mainstay in the topical treatment of atopic dermatitis.7

 

Fluocinolone acetonide is a corticosteroid primarily used in dermatology to reduce skin inflammation and relieve itching. It is a synthetic hydrocortisone derivative. A typical dosage strength used in dermatology is 0.01–0.025%. Although studies have shown that the percutaneous absorption of topically applied substances in children is comparable with that of adults, children have a higher ratio of skin surface area to body mass and, thus, risk increased systemic absorption of topically applied medication relative to weight.8 To overcome this disadvantage, we have investigated controlled topical drug delivery systems wherein Fluocinolone acetonide (FA) is entrapped in microsponge delivery system (MDS).

 

2. MATERIALS AND METHODS:

2.1. Materials

FA was donated by Glenmark Pharmaceuticals Ltd., India. Methocel® K100MCR Premium EP (hydroxypropylmethyl cellulose, HPMC) was supplied by Colorcon; Eudragit RS 100 was from Degussa-Röhm GmbH & Co. (Germany). Carbopol 934 was donated from Lubrizol Advanced Croton oil was procured from Sigma Chemicals Co., USA. Materials India Pvt. Ltd. Polyvinyl alcohol (PVA 75,000) and triethyl citrate were purchased from Sigma (USA). All other chemicals used for analysis were analytical grade.

 

Table 1: Formulation of FA gels containing free and microsponge-entrapped drug

 

Ingredients

Formulations %w/w

FA (free or entrapped, equivalent to)

0.025

Propylene glycol

40.00

Methanol

8.00

Menthol

0.04

Methyl paraben

0.18

Propyl paraben

0.02

Sodium metabisulphite

0.10

Disodium edetate

0.10

Carbopol

1.00

Triethanolamine

Qs

Lavender

Qs

Purified water qs to make

100

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.2. Preparation of FA microsponges

The microsponge formulations containing FA were prepared by procedures explained in detail somewhere by quasi-emulsion solvent diffusion method. 9 FMA formulations FMA1 to FMA7 were prepared by using Eudragit RS 100 in ethyl alcohol and triethylcitrate (TEC). MDS Formulation (FMB) was also prepared by suspension polymerization of styrene with divinyl benzene (DVB) with 25 % crosslinking and drug was entrapped by ethanol entrapment. FA microsponges by entrapment process were prepared by taking 1.5 g of the drug solution in 1.5 g ethanol was added to the 1.5 g blank styrene microsponges in an amber bottle. Bottle was arranged on a roller mill and mixed for 1 h. The mixture was dried in an oven at 65 °C for 2.5 h. This process was repeated for a second entrapment step for the remaining 1.5 g drug solution in 1.5 g ethanol and the drying process was held at 50 °C for 24 h. 10

 

For the evaluation of the effect of drug: polymer ratio on the physical characteristics of microsponges, seven different weight ratios of drug to Eudragit RS 100 (1:1, 3:1, 5:1, 7:1, 9:1, 11:1 and 13:1) were employed.

 

2.3. Compatibility studies

Compatibility of drug with reaction adjuncts was studied by Fourier Transform Infra-red spectroscopy (FT-IR). Effect of process of entrapment on crystallinity of the drug was studied by Differential Scanning Colorimetry (DSC). 11, 12, 13

 

2.4. Determination of production yield and loading efficiency

The production yield of the microparticles was determined by calculating accurately the initial weight of the raw materials and the last weight of the microsponge obtained.14

 

The loading efficiency (%) of the microsponges was calculated according to the following equation:

 

2.5. Particle size analysis

Particle size and size distribution studies of microsponge-particles were done by using particle size analyzer (Mastersizer 2000, Version 2.0, Malvern Instruments Ltd, UK). The results are the average of three analyses. The values (d50) were expressed for all formulations as mean size range.

 

2.6. Surface topography of microsponges

For surface topography, prepared microsponges were coated with platinum studied by scanning electron microscopy (SEM; JEOL-JSM, 6360, Japan) under vacuum at room temperature. 15

 

2.7. Drug release from microsponges

Accurately weighed loaded microsponges were placed within 40 ml of ethanol, in 50 ml glass bottles. The latter were horizontally shaken at 37 °C at pre-determined time intervals. Aliquot samples were withdrawn (replaced with fresh medium) and analyzed UV-spectrophotometrically 238 nm. 16 The content of C24H30F2O6 was calculated taking the specific absorbance, 355. Solutions were protected from light throughout the assay.

 

2.8. Preparation of FA gels

Gels of FA are prepared by using following formula shown in Table 1. A clear dispersion of Carbopol was prepared in water using moderate agitation. FA was dissolved in propylene glycol and methanol. Various ingredients viz. parabens, sodium metabisulphite and disodium edetate were dissolved in water and added to the drug solvent system. Triethanolamine was used to neutralize and volume was made with water. Gels prepared were degassed by ultrasonication.

 

2.9. Anti-inflammatory activity by ear edema measurement

Male Swiss mice (25–35 g) housed at 22±2 ⁰C under a 12-h light/12-h dark cycle and with access to food and water, were used in the experiments, which were performed during the light phase of the cycle. The animals were allowed to acclimate to the laboratory for at least 2 h before testing and were used only once. Experiments reported in this study were performed after approval by the Animal Ethics Committee of our College and were carried out in accordance with the CPCSA guidelines.


Table 2: Effect of Drug-polymer ratio on microsponge properties, Eudragit RS 100 formulations

Formulation code

Drug-polymer ratio

Production yield (%)

loading efficiency (%±SD)

Mean particle size (μm± SD)

FMA1

1:1

55.75

86.76±0.14

82.26±4.62

FMA2

3:1

77.81

87.71±0.02

68.90±3.82

FMA3

5:1

81.32

89.72±0.13

52.89±5.69

FMA4

7:1

82.35

92.75±0.08

43.93±7.29

FMA5

9:1

82.89

92.19±0.08

37.89±6.72

FMA6

11:1

84.46

93.89±0.11

37.24±2.37

FMA7

13:1

87.23

93.88±0.09

31.34±2.73


Figure 1: Scanning electron micrographs of FA microsponges (FMA3 formulation).


 


Figure 2: FTIR spectra of pure FA, microsponge formulations FMA3 and FMB formulations.

 

Edema was induced in the right ear by topical application of 0.1mg/ear of croton oil dissolved in 20μL of acetone. In house gels of FA containing free, entrapped drug and marketed gel were applied topically simultaneously with the croton oil. Ear thickness was measured before and 6 h after the induction of inflammation using a digital vernier caliper.17, 18

 

The results are presented as means ± S.E.M. Data were subjected to analysis of variance (ANOVA), p < 0.05 was considered as indicative of significance; using the GraphPad Software, USA (trail version).

 

3. RESULT AND DISCUSSION:

3.1. Preparation of FA microsponges

Free flowing powder particles of MDS were also obtained by quasi-emulsion solvent diffusion method with Eudragit RS 100 in ethyl alcohol-TEC. The method seems to be promising for the preparation of fluocinolone acetonide microsponges with being easy,

 

reproducible, rapid method. Microsponges using drug: Eudragit ratio 5:1 (FMA3) was further investigated for compatibility studies, drug release and anti-inflammatory activity after entrapment in carbopol 934 gels (0.025%w/w). Agitation speed employed was 500 rpm, using three blade propeller stirrers. The representative scanning electron micrographs of FA microsponges (FMA3) are shown in figure 1. It is observed that the microsponges have predominantly spherical shape and contain numerous pores.

3.2. Production yield, loading efficiency and particle size analysis

The production yield, loading efficiency and mean particle size of FA microsponge formulations are given in Table 2. The readings are mean of three different measurements ±SD. It was found that production yield increases with increase in drug: polymer ratio. Particle size of microsponges was also found much affected by drug: polymer ratio while loading efficiency was not much affected.

 

Figure 3: DSC thermograms of pure FA; microsponge formulations FMA3 and FMB; polymers: blank styrene MDS, Eudragit RS 100

 

Figure 4: In vitro drug release profiles of FA from microsponge formulations FMA3 and FMB.

 

Figure 5: Effect of topical gels of fluocinolone acetonide applied topically on croton-oil-induced ear edema. FFA: In-house gel containing free FA, FMA3: FA entrapped in Eudragit MDS and FMB: FA entrapped in Ethanol entrapped styrene MDS.

 

3.3. Compatibility studies

Figure 2 gives the FTIR spectra of pure FA, Eudragit RS 100 MDS and styrene MDS microsponge formulations. Fundamental peaks of FA at 1710 (ketonic C=O stretch, duplet), 1668, 1625 and 1069 (C=O stretch) cm−1 were seen as observed retained, shows that there was no primary chemical interaction during microsponge preparation and drug was stable in all microsponge formulations.

 

DSC provides information about the physical properties of the sample as crystalline or amorphous nature and demonstrates a possible interaction between drug and other compounds in microsponges.19 The thermal behaviour of FA, Eudragit RS 100 MDS, Eudragit based FA microsponge and styrene MDS microsponge formulations are shown in graphs presented in figure 3. Endothermic peak at 266 ⁰C corresponding to the melting point of drug in the crystalline form. In the DSC curves of formulations, characteristic peaks of FA and polymer system were seen, showed that drug was in its proportionate crystalline form as in pure drug. In the DSC curve of FMC formulation, the degradation peak concerning Eudragit and styrene polymer was observed at higher temperature (~ 380 and 395 °C respectively).

 

3.4. Drug release from microsponges

The drug release profiles of the microsponge formulations are illustrated in Figure 4. Cumulative percent drug release was maximum 4.38 % in the first 1.5 h for all formulations. Burst effect was observed (22.44±3.62% for FMA3, 28.28±1.19 % for FMB4 and 18.18±1.11 for FMC) at 2h; could be due to the surface adsorbed drug and porous nature of microsponges that provides channel for release of the drug.20 Due to smaller pore diameter of the microsponge formulation prepared by suspension polymerization, in vitro drug release from FMB showed slower release compared with the Eudragit based microsponge formulations.

 

3.5. Anti-inflammatory activity by ear edema measurement

As edema can be indicative of inflammation, anti-edematogenic activity was evaluated against croton-oil-induced dermatitis 6 h after its topical application to the skin of the ear. As shown in figure 5, topical application of FA gels caused a significant inhibition of croton-oil-induced edema after application of 0.05 mg per ear of Swiss mice. The results were found significant (p < 0.05), suggests that anti-inflammatory activity of fluocinolone acetonide was retained after entrapment in different microsponge delivery systems.

 

ACKNOWLEDGEMENT:

Authors are thankful to Wallace Pharmaceuticals Ltd., Nirancal Road, Curti, Ponda, Goa for providing gift sample of fluocinolone acetonide.

 

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Received on 06.12.2008       Modified on 20.12.2008

Accepted on 30.12.2008      © RJPT All right reserved

Research J. Pharm. and Tech. 1(4): Oct.-Dec. 2008; Page 502-506