formulation and evaluation of etoricoxib methyl …

www.wjpps.com Vol 6, Issue 9, 2017.

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Vinayak et al. World Journal of Pharmacy and Pharmaceutical Sciences

FORMULATION AND EVALUATION OF ETORICOXIB METHYL

SALICYLATE MENTHOL MICROSPONGE GEL FOR TOPICAL

DRUG DELIVERY

*1

Vinayak K., 2Ashalatha,

3Shabaraya A. R. and

4A. Sravanthi

*1Asst, Professor, Srinivas College of Pharmacy, Valachil, Mangalore (Karnataka).

2Student, Srinivas College of Pharmacy, Valachil, Mangalore (Karnataka).

3Principal. HOD of Pharmaceutics Dept, Srinivas College of Pharmacy Valachil, Mangalore

(Karnataka).

4Asst. Professor, Srinivas College of Pharmacy, Valachil, Mangalore (Karnataka).

ABSTRACT

One of the most efficient approaches of novel drug delivery system for

topical application is Microsponges. These are polymeric delivery

systems composed of porous microspheres. They are tiny sponge-like

spherical particles with a large porous surface. Their high degree of

cross-linking results in particles that are insoluble, inert and of

sufficient strength to stand up to the high shear. Etoricoxib

Cyclooxigenase-2(cox-2) inhibitor a non steroidal anti-inflammatory

drug was formulated as microsponges using Ethyl cellulose and

Eudragit RS 100 polymers by solvent evaporation method and

evaluated for drug-polymer compatability by using FTIR, particle size,

production yield, loading efficiency, Further selected microsponges were formulated into gel

using carbopol 934(0.5% and 1%) and evaluated for various parameters like clarity, viscosity,

pH, spreadability, In-vitro diffusion, Skin irritation and stability studies were performed. And

it was found that all characteristic features shows significant results. The gel prepared by

these microsponges shows most efficient in uniform distribution and release rate of drug than

the any other form.

KEYWORDS: Etoricoxib, microsponges, gel, topical drug delivery, controlled release.

WORLD JOURNAL OF PHARMACY AND PHARMACEUTICAL SCIENCES

SJIF Impact Factor 6.647

Volume 6, Issue 9, 1084-1100 Research Article ISSN 2278 – 4357

*Corresponding Author

Vinayak K.

Asst, Professor, Srinivas

College of Pharmacy,

Valachil, Mangalore

(Karnataka).

Article Received on

23 June 2017,

Revised on 14 July 2017,

Accepted on 04 Aug. 2017

DOI: 10.20959/wjpps20179-9970


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INTRODCTION

Microsponge drug delivery system

One of major approach to solve the Complications with topical formulation like unappealing,

greasiness, stickiness Un-controlled evaporation of active ingredient, unpleasant odour and

potential incompatibility of drugs with the vehicles is done by formulating into

microsponges. There highly cross-linked spherical polymeric nature provide sufficient

strength to with stand high shear results in particles that are insoluble, inert and of to

commonly used in manufacturing of creams, lotions, and powders. It have a capacity to

“load” a high degree of active materials in and on to the surface of the particle and also have

large capacity for entrapment of actives, up to three times its weight which differentiates

microsponge products from other types of dermatological delivery systems. the size of pore

diameter is smaller than bacteria, ranging from 0.007 to 0.2 µm prevents Bacterial

contamination of the materials entrapped in the microsponge, the release of drug can be

controlled through diffusion or other variety of triggers, including rubbing, moisture, pH,

friction, or ambient skin temperature. Microsponges are prepared by Liquid-liquid suspension

polymerization and Quassi-emulsion solvent diffusion.

MATERIAL AND METHODS

Organoleptic characteristics

The colour, odour and taste of the drug were characterized and recorded using descriptive

terminology.

Solubility study

The solubility of the Etoricoxib was determined in distilled water, phosphate buffer pH 6.8,

methanol, ethanol and dichloromethane by adding an excess amount of drug to 10 ml of

above solvents in conical flasks. The flasks were kept at 25±0.5°C in isothermal shaker for

24hrs to reach equilibrium. The equilibrated samples were removed from the shaker and

centrifuged at 4000 rpm for 15mins. The supernatant was taken and filtered through

whatmann filter paper. The concentration of Etoricoxib was determined in supernatant after

suitable dilution by using UV-visible spectrophotometer at 234 λmax.

Drug-excipient compatibility study

FTIR can be used to investigate and predict any physicochemical compatibility between

different excipients. IR spectra matching approach was used for detection of any possible

chemical compatibility between the drug and polymer. Scan was done in the range of 4000 to


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400 cm-1

in a FTIR spectrophotometer (F.T.I.R, Shimadzu). The IR spectrum of the physical

mixture was compared with those of pure drug and polymer and peak matching was done to

detect any appearance or disappearance of peaks.

FORMULATION

Microsponge

The microsponges were prepared by quasi-emulsion solvent diffusion method[1,2]

The inner

phase was prepared by dissolving the Eudragit RS100/ Ethyl cellulose in 20 ml of

dichloromethane under sonication. This was followed by addition of Etoricoxib with stirring.

Outer phase was prepared by dissolving PVA in distilled water at 40˚C.The inner phase was

then added drop wise into outer phase with stirring at 1000 rpm. After 4hrs of stirring,

microsponges were formed due to the removal of solvent from the system by evaporation.

The microsponges were washed with water, filtered and dried at 40˚ C for 12hrs.

Table 1: Composition of Etoricoxib microsponges.

Ingredients F 1 F 2 F 3 F 4 F 5 F 6 F 7 F 8

Etoricoxib (gm) 1 1 1 1 1 1 1 1

Ethyl Cellulose (mg) 200 300 200 300 - - - -

Eudragit RS 100 (mg) - - - - 200 300 200 300

PVA(mg) 300 300 200 200 300 300 200 200

Dichloromethane(ml) 20 20 20 20 20 20 20 20

Water(ml) 200 200 200 200 200 200 200 200

EVALUATION OF MICROSPONGE

Particle size and shape[2]

The particle size was determined by using optical microscopy. It was used to determine the

shape and the outer structure of the particles.

Morphology and surface topography of the microsponges[2]

For morphology and surface topography, prepared microsponges were coated with gold-

palladium under an argon atmosphere at room temperature and then the surface morphology

of the microsponges was studied by scanning electron microscopy (SEM).

Drug content

The drug content was determined by dissolving 100 mg eq. weight of Etoricoxib

microsponge in 100 ml of PBS pH 6.8(stock solution “A”). From (stock solution “A”) 10ml

solution is diluted up to 100ml of PBS pH 6.8(stock solution “B”). From (stock solution “B”)


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1ml solution is diluted up to 10ml with PBS PH 6.8. Then the absorbance is measured by Uv

spectrophotometer against blank at λ max 234 nm and the drug content was calculated.

Determination of loading efficiency and production yield[3]

The loading efficiency (%) of the microsponges was calculated according to the Following

equation.

The production yield of the microsponges was calculated by accurately weighing the initial

weight of the raw materials and the final weight of the microsponges obtained.

b) MICROSPONGE GEL[4,5]

Procedure

Required quantity of polymer was weighed and it was sprinkled slowly on surface of purified

water and kept for 24 hrs with continuous stirring by mechanical stirrer till uniformity was

obtained. With continuous stirring, triethanolamine was added to neutralize the gel and

maintain its pH. Appropriate quantity of microsponge of Etoricoxib was dissolved first in

ethanol along with weighed amount of menthol and methyl salicylate which was then added

to the gel. Finally Methyl Paraben was added to the gel with continuous stirring till get

dispersed in gel completely.

Table 2: Composition of Etoricoxib microsponge gel formulation.

Ingredients Polymer: Ethylcellulose Polymer:EudragitRS100

EMF1 EMF2 EMF3 EMF4

Etoricoxib Microsponge Eq.to1%

W/W

Eq.to1%

W/W

Eq.to1%

W/W

Eq.to1%

W/W

Carbopol 934 0.5% 1% 0.5% 1%

Menthol(mg) 50 50 50 50

Ethanol(ml) 2 2 2 2

Methyl paraben(gm) 0.09 0.09 0.09 0.09

Triethanolamine q.s q.s q.s q.s

Methyl salicylate 0.1% 0.1% 0.1% 0.1%

Purified water up to 10gm q.s q.s q.s q.s


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Evaluation of Microsponge Gel formulation

Physical characteristics[6]

The gels were inspected visually for its colour, clarity, consistency, spreadability.

pH measurement[13]

The pH of microsponge formulation was determined by using digital pH meter.1gm of gel

was dissolved in 100ml of distil water and it was placed for 2hr. the measurement of pH of

each formulation was done in triplicate and average values were calculated.

Spreadability[7]

For the determination of spreadability, excess of sample was applied in between two glass

slides and was compressed to uniform thickness by placing 125g weight for 5 min. weight (1

g) was added to the pan. The time in which the upper glass slide moves over to the lower

plate was taken as measure of spread ability.

S = M.L / T

M- Weight tied to the upper slide

L - Length moved on the glass.

T - Time Taken

Clarity[8]

All developed gels were tested for homogeneity by visual inspection after the gels were set in

the container and also for presence of any aggregate.

1. Content uniformity[9]

Drug content of gel was determined by dissolving accurately weighed 1gm of gels in

Phosphate buffer pH 6.8. After suitable dilution absorbance was recorded by using UV-

visible spectrophotometer (Jasco) at 234 nm. Drug content was determined using slope of

standard curve.

2. Viscosity measurement[10]

Brookfield viscometer was used for viscosity determination. The formulation (10g) was taken

and it was allowed to calibrate for 5min before measuring the dial reading using spindle no

64 at 20rpm.

3. In-vitro drug diffusion study of the prepared gel[2]

The diffusion medium used was Phosphate buffer pH 6.8, carried out using Franz diffusion


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cell. The diffusion cell was placed on the magnetic stirrer the outlet of the reservoir was

maintained at 37±0.5ºC. The receptor compartment was filled with Phosphate buffer pH 6.8,

pre hydrated cellophane paper was used as the membrane. The speed of the stirrer was kept

constant. 2ml of sample was pipetted out for every 1hr time interval.

4. Skin irritation study[11]

Selection of animal: Two healthy rabbits, weighing 2kg were selected for study. the

experimental protocol was subjected to the scrutiny of the institutional animal ethics

committee (Ref: SCP/IAEC/F150/P95/2016) date: 27/01/2016 and was cleared by same

before being the experiment.

0.5 gm of sample was evenly applied to a small area of (2 cm square) of the closely clipped

skin of each of the two rabbits. The site of application was secured with cotton gauze and it

was covered with a semi-occlusive dressing. One site served as test whiles the other as

control. At the termination of 4 hours of exposure period, the bandages/gauze was removed

and the treatment sites were cleaned with wet gauze to remove any residual test substance.

Skin reaction and sensitivity at the site of application was subjectively assessed and scored

once daily at 1, 24, 48, 72 hours, 7 and 14 days after patch removal. A ‐ No reaction, B ‐

Slight, patchy erythema, C ‐ Slight but confluent or moderate but patchy erythema, D ‐

Moderate erythema, E ‐ Severe erythema with or without edema.

Table 3: Classification systems for skin irritation study.

Reaction Score

Erythema 1

No erythema 0

Very slight erythema 2

Negligible irritation 0

Slight irritation 0.4 – 0.5

Moderate irritation 0.5 – 1.9

Severe irritation 1.9- 2

Redness 1

No redness 0

5. Stability Study[12]

The prepared microsponge gel formulations were subjected to stability studies as per ICH

Guidelines. The selected batch was packed in tightly closed containers wrapped in aluminium

foil and kept at 25±20c at (60±5%RH) for 60 days in a stability chamber and also at 2-8

0c

temperature in a refrigerator.


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RESULTS AND DISSCSSION

Preformulation study of etoricoxib

Table 4: Organoleptic properties of Etoricoxib.

Properties Reported Observed

Appearance white to off-white powder white to off-white powder

Taste Tasteless Tasteless

Odour Odorless Odorless

Table 5: Solubility of Etoricoxib.

Solvents Reported Observed

Distilled water 0.01gm/ml 0.008gm/ml

Phosphate buffer pH 6.8 0.07gm/ml 0.055gm/ml

Ethanol 1.0gm/ml 0.91gm/ml

Methanol 1.2gm/ml 1.11gm/ml

Dichloromethane 1.10gm/ml 1.06gm/ml

Drug excipients compatibility studies: (Fourier Transform Infrared Spectroscopy)

Figure 1: F.T.I.R spectra of pure drug Etoricoxib.

Figure 2: FTIR spectra of Etoricoxib + ethyl cellulose


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Figure 3: F.T.I.R spectra of pure drug Etoricoxib + Eudragit RS100.

Figure 4: F.T.I.R spectra of pure drug Etoricoxib+ Carbopol 934.

EVALUATION OF ETORICOXIB MICROSPONGES

Table 6: Evalation of particle size, production yield, drug content and loading efficiency

Formulation

code

Average particle

size (µm)

Production

yield (%)

Actual drug

content (%)

Loading

efficiency (%)

F1 77.34 83.33±0.23 75.7 75.5±0.35

F2 90.3 86.15±0.30 72.4 72.65±0.24

F3 113.48 75.83±0.41 77.2 77.55±0.31

F4 170.49 89.23±0.27 73.6 74.3±0.49

F5 80.15 84.16±0.29 77.8 77.5±0.35

F6 97.12 82.55±0.51 73.9 73.5±0.35

F7 128.08 90.83±0.41 79.01 79.5±0.35

F8 177.94 96.15±0.30 76.2 76.5±0.35


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Surface topography and morphology of Etoricoxib microsponges

Figure 5: Scanning Electron Microscope image of microsponge surface of F3

microsponge formulation.

Figure 6: Scanning Electron Microscope image of F3 microsponge formulation.

EVALUATION OF ETORICOXIB MICROSPONGE GEL.

Table 7: Physical characteristics of etoricoxib microsponge gel.

Formulation

code Clarity pH

Spreadability

(gms.cm/sec)*

Drug

content

(%)

Viscosity

(cp)

EMF1 +++ 6.9±0.035 18.05±0.103 80.49% 23500

EMF2 ++ 6.8±0.035 28.13±0.0042 83.65% 24890

EMF3 +++ 6.3±0.035 19.78±0.1157 81.85% 24060

EMF4 ++ 6.4±0.035 27.45±0.0151 85.13% 26490

Clarity: + (turbid), ++ (clear), +++(very clear, glassy) * Average of 3 trials (average + S.D)

(n=3).


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Table 8: In-vitro permeation data of Etoricoxib microsponge gel

Time

(Hrs)

% Cumulative drug release

EMF1 EMF2 EMF3 EMF4

1 16.631 16.908 17.364 17.856

2 27.774 24.757 27.734 30.320

3 34.572 32.264 35.360 38.013

4 39.917 39.555 41.538 45.192

5 43.255 44.692 44.407 50.033

6 46.448 50.016 47.507 54.386

7 48.108 54.936 49.340 57.579

12 54.305 67.096 56.557 69.227

Figure 7: Graph of %CDR v/s time of Etoricoxib microsponge gel formulations.

KINETIC STUDY OF MICROSPONGE GEL

Figure 8: Graph of Zero order release kinetics of Etoricoxib microsponge gel.


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Formulations

Figure 9: First order release kinetics of Etoricoxibmicrosponge gel.

Figure 10: Korsmeyer-Peppas release kinetics of Etoricoxib microsponge gel.

Figure 11: Graph of Higuchi matrix release kinetics of Etoricoxib microsponge gel.


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Table 9: Kinetics release study of Etoricoxib umicrosponge gel formulations.

Formulation

code

Zero

order

First

order

Higuchi

matrix

Peppas plot

R2 values n values

EMF1 0.752 0.837 0.958 0.754 0.254

EMF2 0.888 0.972 0.991 0.778 0.245

EMF3 0.765 0.855 0.963 0.754 0.257

EMF4 0.835 0.946 0.985 0.766 0.258

Figure 12: Skin irritation test data of the best formulation of microsponge gel.

Table 10: Observed results of skin irritation tests.

Time period

Microsponge topical gel

EMF2 EMF4

A B A B

Before application 0 0 0 0

1 hr 0 0 0 0

24 hrs 0 0 0 0

48 hrs 0 0 0 0

72 hrs 0 0 0 0

7 days 0 0 0 0

14 days 0 0 0 0

A: Control B: Test


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Stability studies of the selected formulations (EMF2 and EMF4)

Table 11: Evaluation of physicochemical parameters of the formulation EMF2.

Physicochemical

Parameters

Time (Days)

0 30 60

pH A* 6.8 6.8 6.8

Drug Content (%) A* 83.8 82.5 82

Viscosity(cps)** A* 24890 24889 24887

Table 12: Evaluation of physicochemical parameters of the formulation EMF4.

Physicochemical parameters

Time (Days)

0 30 60

pH A* 6.4 6.4 6.4

Drug Content (%) A* 84.5 84.1 83.8

Viscosity(cps)** A* 26490 26488 26487

A*: 25±2°C and 60±5% RH, **: Viscosity measured at 100 rpm.

Table 13: In-vitro diffusion studies of formulation EMF2.

Time

(hrs)

%CDR

At 0 day

After 30 Day After 60 day

25±2°C and

60±5% RH

25±2°C and

60±5% RH

1 16.908 16.589 16.268

2 24.757 24.492 24.098

3 32.264 31.924 31.756

4 39.555 39.326 39.100

5 44.692 44.387 44.035

6 50.016 49.893 49.559

7 54.936 54.692 54.401

12 67.096 66.896 66.694

Figure 13: Graph of %CDR v/s Time of stability study of EMF2 formulation.


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Table 14: In-vitro diffusion studies of formulation EMF4.

Time

(hrs)

%CDR

At 0 day

After 30 Day After 60 day

25±2°C and

60±5% RH

25±2°C and

60±5% RH

1 17.856 17.558 17.256

2 30.320 30.092 29.889

3 38.013 37.713 37.513

4 45.192 44.892 44.599

5 50.033 49.833 49.649

6 54.386 54.102 53.889

7 57.579 57.259 56.934

12 69.227 68.923 68.669

Figure 14: Graph of %CDR v/s Time of stability study of EMF4 formulation.

DISCUSSION

Etoricoxib microsponges were prepared by Quasi-emulsion solvent diffusion method using

Eudragit RS 100 and Ethyl cellulose as rate controlling polymers. It was then evaluated for

physicochemical properties like organoleptic properties, melting point, solubility, drug

polymer compatibility studies using FTIR and drug content. The best formulation for the

preparation of gel was selected on the basis of drug content of microsponge and it was

evaluated for parameters like pH, drug content, viscosity, In-vitro diffusion study and

primary skin irritation test. Stability studies were performed as per ICH guidelines (Q1A).

The melting point of Etoricoxib was found to be 136.5˚C, Etoricoxib is freely soluble in

methanol, ethanol, and dichloromethane and sparingly soluble in water. The study was

carried out to select suitable dissolution medium for in-vitro release studies, phosphate buffer


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of pH 6.8 was selected for dissolution studies. By FTIR study it was found that there was no

interaction of Drug –polymer confirming the stability of drug in the formulations. Etoricoxib

microsponges were prepared by Solvent evaporation method using Eudragit RS100 and

ethylcellulose as rate controlling polymers. Microsponge formulations were prepared and

evaluated for production yield, loading efficiency, drug content and morphology studies.

Based on the drug content data F-3 and F-7 formulations were selected and incorporated into

carbopol 934gel and evaluated for physicochemical properties, drug content, primary skin

irritation test and diffusion studies. production yield and loading efficiency were calculated

for all the microsponge formulations, upto 96.15±0.30% of production yield and 79.5±0.35%

of loading efficiency was found with microsponges of both the polymers. The drug content of

formulation F3 using ethyl cellulose shows 72-77%. The morphology of the selected

microsponge formulation were investigated by SEM. it was observed by SEM analysis that

the microsponges were finely spherical, uniform in shape, no intact drug crystals are seen

visually and inner structure was consist of porous in nature with void spaces.

Physicochemical evaluation of Etoricoxib microsponge gels like clarity, pH determination,

Viscosity studies, Spreadability, Drug content uniformity, In-vitro diffusion study, Skin

irritation study, was performed it was found that clear with moderate viscocity and

28.13±0.0042gm.cm/sec of spreadability was obsereved, in the drug content study 85.13%

was observed. The highest cumulative percentage amount of the drug released from the

microsponge gel at the end of 12hrs was found to be 69.227%. During skin irritation test till

14th

day no such irritation was observed and there were no significant changes observed after

3 months of stability testing.

CONCLUSION

The present study has been satisfactory attempt has been made to formulation and evaluation

of etoricoxib methyl salicylate menthol microsponge gel for topical drug delivery. From the

reproducible results of executed experiments: it can be concluded that Preformulation studies

on Etoricoxib comply with the reported literature limits. The FTIR spectra revealed that there

was no interaction between drug and polymer. From, the present study it can be concluded

that microsponge can be prepared by Quasi-emulsion solvent diffusion method using

different concentration of Ethyl cellulose and Eudragit RS100 as the rate controlling

polymers. All the microsponge formulations were subjected to particle size, production yield,

loading efficiency, drug content, SEM. F3 and F7 microsponge selected as best formulation

and conveniently incorporated into carbopol 934 (0.5%) and (1%) gel. All the formulations of


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gels were evaluated for various parameters like clarity, viscosity, pH, spreadability, drug

content, in-vitro diffusion studies, depending upon the in-vitro release value the formulation

was subjected to kinetic analysis and the results were found to be reproducible. The skin

irritation test was performed on rabbits according to Draize patch test. The results suggest

that neither there is edema nor symptoms of adverse effects hence’0’ score was given after

each observation indicating Etoricoxib microsponge gel can be conveniently incorporated

into gels without any irritation. Stability studies as per ICH guidelines (Q1A) of formulation

EMF2 and EMF4 were carried out for short duration of time (3 month). There was no

significant change found in the evaluation of microsponge gel which indicates that the

formulation EMF2 and EMF4 is fairly stable at storage conditions.

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