peppermint oil based drug delivery system of aceclofenac with improved anti-inflammatory activity...

7/28/2019 Peppermint oil based drug delivery system of aceclofenac with improved anti-inflammatory activity and reduced

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ISSN: 2321-2969

Int. J. Pharm. Biosci. Technol.

Pol et al Pg. 89

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International Journal of Pharma Bioscience and Technology. 2013; 1(2): 89-101

Journal home page: www.ijpbst.com

PEPPERMINT OIL BASED DRUG DELIVERY SYSTEM OF ACECLOFENAC

WITH IMPROVED ANTI-INFLAMMATORY ACTIVITY AND REDUCED

ULCEROGENECITY

Anuradha S. Pol1*, Pratikkumar A. Patel2, Darshana Hegde1

1* Department of Pharmaceutics, Bombay College of Pharmacy, Kalina, Santacruz (E), Mumbai 400 098.Maharashtra, India

2Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, SVKM's Narsee

Monjee Institute of Management Studies, Vile Parle, Mumbai, Maharashtra, India.

Corresponding Author*

E-mail address- [email protected]

ABSTRACT:

Aceclofenac (ACF), a nonsteroidal anti-inflammatory (NSAID) BCS class II drug belonging to the class of

phenyl acetic acid derivatives exhibiting antipyretic, anti-inflammatory and analgesic activities. Many

strategies have been employed for improving solubility and thus bioavailability of this drug moiety. Butthis is a first report on peppermint oil based oral SMEDDS of ACF for achieving a synergistic anti

inflammatory activity by combining NSAIDS with essential oils such as mint oils. Thus, the present

investigation was designed with an aim to improve the solubility, dissolution rate, oral bioavailability andeventually anti-inflammatory activity of ACF by incorporating into peppermint oil based SMEDDS. Thesolubility of ACF was determined in various lipid based excipients viz, essential oils and other lipophiles,

surfactants and cosurfactants. Further emulsification studies were carried out in order select specific oil-surfactant-cosurfactant combinations for plotting the pseudo ternary phase diagrams which were thenconstructed to identify the existence of microemulsion region. The formulations of ACF-SMEDDS were

optimized using pseudo-ternary phase diagrams analysis and studied for drug loading and lipid content.The average globule size of ACF-SMEDDS was less than 100 nm and was confirmed by transmission

electron microscopy. The optimized formulation exhibited about 99% release of ACF from the SMEDDSfilled in capsules. Furthermore, ACF SMEDDS showed 80 7.30 % inhibition after 4 hr of treatment

against carrageenan induced paw. In addition to this SMEDDS showed least ulcer score as compared toother treatment group. Thus, the developed SMEDDS were found to exhibit less GI tract toxicity and

showed superior anti inflammatory action compared to plain drug.

Key words:Aceclofenac, NSAID, self microemulsifying drug systems, peppermint oil, rat paw edema

INTRODUCTION

The oral route is the most preferred route of drug

delivery due to the obvious advantages associatedwith it. Drug discovery in recent years have led to

invention of drug molecules having poor aqueoussolubility which in turn result in poor oral

bioavailability, high intra- and inter-subjectvariability and lack of dose proportionality [1].

Delivery of about 35-40% of the drug compounds

by oral route is hampered because of its highlipophilicity. Several formulation strategies have

been developed to enhance solubilization of

lipophilic/hydrophobic drugs for improving theiroral delivery. Lipid based oral delivery is one of

the most promising approach in this direction.These systems incorporate the lipophilic drug into

inert lipid vehicles such as oils, micellar systems,liposomes, lipid emulsions, specialized emulsions

(multiple emulsions and microemulsions) and

emulsion preconcentrates. The term emulsion

Research Article

Received: 06 May 2013, Accepted: 20 May 2013


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Pol et al Pg. 90

preconcentrates include self-emulsifying and self-microemulsifying drug delivery systems [2].

Fig.1. Chemical structure of Aceclofenac

Aceclofenac (ACF) is a phenyl acetic acid- basednonsteroidal anti-inflammatory (NSAID) drug withpotent antipyretic, anti-inflammatory and

analgesic activity. It is belongs to class II BCSclassification (low solubility/high permeability),

possesses very slight solubility in water.Currently, it is commercially available as

conventional and sustained release tablets. Thedrug is reported to exhibit slow and/or incomplete

dissolution from this dosage form in gastro-intestinal fluids, leading to low and variable

bioavailability [3]. Improvement of dissolution ofACF from its oral dosage forms is thus, an

important issue for enhancing its bioavailabilityand therapeutic efficacy [4]. Various approachessuch as suspension in oily formulation wherein a

drug is suspended in oily base using suspending

agent such as beeswax, solubilization in aqueoussoluble base and solid dispersions have beenstudied. But these formulations exhibit certain

drawbacks such as delayed dissolution in case ofoily suspension and less significant increase in

dissolution rate when solubilised in aqueoussoluble bases [5]. In the light of the

aforementioned issues, there is a need of adelivery system which would improve the oral

delivery of this hydrophobic drug bycircumventing its poor aqueous solubility and

enhance its dissolution rate thereby leading tofaster onset of action with reduction in GI mucosal

toxicity.Microemulsions are defined as thermodynamically

stable, transparent, isotropic, low viscositycolloidal dispersions and are mixtures containing

at least three components, water, oil andsurfactant. Self-microemulsifying drug delivery

systems (SMEDDS) are microemulsionpreconcentrates which offer lipophilic drugs to the

gastrointestinal tract in a dissolved state due tospontaneous emulsification, avoiding thedissolution step and are reported to render more

reproducible plasma concentration profiles and

enhanced bioavailability [6]. These propertiesrender SMEDDS as a good carrier for delivery ofhydrophobic drugs exhibiting adequate solubility

in oil or oil/surfactant blend. SMEDDS arepreferred over preformed microemulsions due to

their improved physical stability, volumeconsideration and ease of formulating them into

hard or soft gelatin capsules for oral delivery [7].

Materials and Methods

Materials

Aceclofenac and Diclofenac acid was procured

from USV Ltd. Mumbai, India. Peppermint oil was agift sample from Keva Flavors Pvt. Ltd, Mumbai,

India. Cremophor EL and Solutol HS 15 was agenerous gift sample from BASF, Mumbai, India.

Gelucire 44/14 and Labrasol were received as agenerous gift from Gattefosse, Mumbai, India.

Hard gelatin capsules were procured fromAssociated Capsules Ltd Mumbai, India. Sodiumlauryl sulfate and ethyl cellulose were procured

from Colorcon. Mumbai, India. Methanol (HPLCgrade), acetonitrile (HPLC Grade), Tween 80,

dichloromethane and triethanolamine (AR grade)were purchased from s. d. Fine Chemicals,

Mumbai, India. All the excipients and reagentswere used as received. Double distilled water was

filtered through 0.45 m membranes and wasprepared freshly whenever required.

Preformulation studies

Solubility studies

The saturation solubility of ACF in various oils,surfactants, and cosurfactants was determined by

shake flask method [8].

Emulsification studies for screening potentialexcipients

Screening of surfactants for emulsifying ability

Peppermint oil IP was selected as oily phasebased on the results of solubility studies. Briefly,

the oil was mixed with surfactants in 1:1 ratio andthe vortexed for 5 minutes to ensure propermixing. From the resultant isotropic mixture 50 mg

of mixture was weighed accurately and diluted to20 ml with double distilled water to yield a fine

emulsion. The resulting emulsions were observedvisually for physical appearance, optical clarity

and separation of dispersed phase over a periodof 8 hr. The resulting systems were also evaluated

for turbidity by using the turbidimetric methoddescribed by Date et al [9].

Screening of cosurfactants

Cosurfactants were screened to evaluate theirrelative efficacy in presence of surfactant and oil.

The oil: surfactant: co-surfactant ratio was kept

constant as 1:2:1. The mixtures were evaluated for


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Pol et al Pg. 91

turbidity by turbidimetric method described byDate et al [9].

Construction of pseudoternary phase diagram

Pseudoternary phase diagrams were constructed

to define the extent of the microemulsion region.Ternary mixtures with varying compositions of

surfactant, co-surfactant and oil were prepared;each of them, representing an apex of the triangle

[10]. The surfactant concentration was varied from20 to 65 % (w/w) and co-surfactant concentration

was varied from 10 to 40% (w/w). The percentageof surfactant, co-surfactant and oil used herein was

decided on the basis of the requirements stated inthe literature for the spontaneously emulsifying

systems [11].

Optimization parameter studied

Influence of drug loading

The selected systems were studied at dose levels

of 50mg, 75 mg, 100mg, 115 mg and 130 mg.Formulations equivalent to 5 mg of drug were

dispersed in 500 ml of double distilled water andwere observed for their dispersability, globule

size and its polydispersity. In addition, they wereexamined for drug precipitation and phase

separation over a period of 24 h.

Effect of lipid content

Suitable formulations were selected for respectivesurfactant-cosurfactant combination based on theresults of earlier studies; effect of drug loading on

globule size. The effect of different concentrationsof lipid on the formulation with respect to change

in globule size was evaluated. Formulations werealso observed for visible signs of drug

precipitation and phase separation.

Formulations of SMEDDS

The optimized formulations were prepared by

dissolving ACF in oily phase by vortexing for 5

min followed by surfactants and cosurfactants andfinal blend was sonicated for 5 min to remove anyair bubbles. A fixed amount of the SMEDDS was

filled in transparent hard gelatin capsules ofrequired sizes using a micropipette. The systems

were then evaluated for further studies.

Characterization

Self-microemulsifying formulations were

evaluated visually (before reconstitution/dilution)for appearance.

Self-microemulsification efficiency

The self-emulsification capacity was assessed forformulations, using a standard USP XXIII

dissolution apparatus II. Each capsule was addedto 500 ml of 0.1 N HCl at 37C 0.5C. Gentle

agitation was provided by a standard stainlesssteel dissolution paddle rotating at 50 rpm. The

lipid-based formulations were assessed visuallyfor the rate of microemulsification and the final

appearance of the dispersion.

Globule size analysis

The capsule was pierced and the contents were

diluted ten times with double distilled water.Formulations were evaluated for globule size by

photon correlation spectroscopy using a Beckmancoulter N5 plus submicron particle size analyzer.

pH determination

The formulations were diluted 100 times withdouble distilled water and the pH of resulting

microemulsions (with and without ACF) wasdetermined in triplicate at 25 2C using a digital

pH meter (Universal Enterprises).

Dilution test

Optimized formulations were diluted 100, 250,500, and 1000 times in different buffer media (pH1.2, pH 3.0, pH 6.8, double distilled water, and

ringer solution). The test was carried out in testtubes maintained at 37 1C in a water bath

shaker with a view to simulate body temperatureand gastric motility in gastrointestinal tract.

Furthermore, formulations were assessed fortransparency, phase separation, globule size and

precipitation of drug at intervals of time up to 8 h.

Zeta potential measurement

SMEDDS (40 mg) was diluted 250 times with pH 1.2

buffer and pH 6.8 buffer. ZetaPALS instrument wasused to measured surface charge (zeta potential)

and electrophoretic mobility of the blank andACF-loaded microemulsions at 25C.

Transmission electron microscopy (TEM)

The morphology of the oil droplets in thenanoemulsion formulations was visualized withTEM CM 200 Philips operating at 200 Kv.Combination of bright field imaging at increasing

magnification and of diffraction modes was used toreveal the form and size of the microemulsion. In

order to perform the TEM observations, themicroemulsion formulations (blank and ACF

loaded) were diluted with 0.45m filtered distilledwater (1/100). A drop of the diluted microemulsion

was placed on the film grid coated with copperand samples were observed after drying.


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Procedure for determining gastriculcerogenicity

The rats were sacrificed eight hours after

administration; their stomachs were removed,incised along the greater curvature, and gently

washed with saline and then mounted inphosphate buffer saline. The extent of erosion ofstomach mucosa was assessed from a scoring

system designed by MerazziUberti Turba asfollows:

0- No erosions;

1- One to three small erosions (4 mm or smaller);2- More than three small erosions or one large

erosion;3- Two large erosions;

4- Three to four large erosions;5- More than four large erosions or lesionproliferation.

The results were expressed in terms of an ulcerindex, which is the average severity of erosions

per rat each group on the scale from 0 to 5 [13].

Statistical Analysis

The statistical significance of the differencebetween mean values was assessed by ANOVAfollowed by Boneferronis multiple comparison

tests for comparison between all groups withsignificance P > 0.05.

RESULT AND DISCUSSION

Preformulation studies

The objective of the preliminary studies was to

screen and select suitable components fordeveloping SMEDDS formulations of ACF from a

large pool of excipients.

Solubility studies

Solubility studies were carried out with an aim of

identifying suitable oily phase andsurfactant/cosurfactants for the development of

ACF SMEDDS. [9]. It is even more important forACF, as the target dose to be incorporated in

SMEDDS is substantially high (100 mg).

Equilibrium solubility of ACF in various oils,surfactants and co surfactants is presented in Fig. 2& 3. All the essential oils showed good solubilizing

capacity compared to other lipophiles. However,discoloration was observed in isotropic mixturesof ACF with essential oils. The only exception to

this behavior was exhibited by peppermint oil IPwhich displayed good physical stability with no

color or odor change even after one week.

Fig. 2: Solubility of ACF in various oily phases Solubility expressed as mean S.D. (n = 3)

Thus ACF exhibited high solubility in the volatile

oils compared to other lipophiles. This

observation indicated that terpenes basedsolubilisers (e.g volatile oils) can also be used for

drug candidates exhibiting limited solubility in the

commonly used lipophiles. These oils could be

explored in the development of lipid- based self-emulsifying drug delivery systems. Based on the

0 50 100 150

Peppermint oil IP

Peppermint oil

Eucalyptus oil IFF

Capryol 90

Lauroglycol FCC

Lauroglycol 90

Labrafil 1944 CS

Labrafil S6

Capmul

Capmul

Capmul MCMCapmul MCM L

Akoline MCM

Concentration of ACF mg/g

OILS


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Pol et al Pg. 94

results, peppermint oil IP was selected as the oilyphase for further studies. Amongst the various

surfactants and cosurfactants screened, (Fig. 3),ACF was found to exhibit solubility in surfactants

in the following sequence: Tween 80 > Gelucire

44/14> Solutol HS 15. ACF exhibited very goodsolubility in various water miscible organic

solvents such as, Polyethylene glycol 400,Transcutol P followed by Labrasol. [14].

Fig. 3: Solubility of ACF in various surfactants and cosurfactants Solubility expressed as mean S.D. (n = 3)

Emulsification studiesScreening of surfactants for emulsifying ability

The optical clarity of the aqueous dispersions canbe measured using standard quantitative

techniques for turbidity assessment. Opticalclarity corresponds to high transmittance, as

opalescent dispersions will scatter incidentradiation to larger extent as compared to

transparent dispersions. The intensity of lightpassing through such dispersion is attributed to

the scattering of light which occurs due to absenceof optical homogeneities in the medium. Hence, %

transmittance could directly be used to predictrelative droplet size of the emulsion.. Based on thisunderlying principle, aqueous dispersions with

high transmittance (lower absorbance) wereconsidered optically clear and oil droplets were

thought to be in a state of finer dispersion [15, 16].It was necessary to identify the combinations of

surfactants and lipophiles that could producestable microemulsions. The turbidimetric studies

were performed for evaluating the ability ofvarious surfactants and co-surfactants to emulsify

the selected oily phases. The percentagetransmittance values of various dispersions are

listed in Table 2. Emulsification studies clearlydistinguished the ability of various surfactants to

emulsify peppermint oil. These studies indicatedthat Cremophor EL and Solutol HS 15 werecomparatively more efficient in emulsifying

peppermint oil followed by Tween 80 andGelucire 44/14.

Table 2: Emulsification efficiency of various

non-ionic surfactants

Surfactants % Transmittance

Cremophor EL 96.45 0.52Solutol HS 15 97.83 0.78

Tween 80 95.83 0.07

Gelucire 44/14 85.83 0.89Data expressed as mean (n = 3)

Interestingly, all the hydrophilic co-surfactantsappeared to improve the emulsification ability of

Cremophor EL and Solutol HS 15. Transcutol P wasfound to exhibit maximum emulsification ability

amongst all the co-surfactants tried. Solutol HS 15exhibited good self-microemulsifying potential as

indicated by the transmittance values (almost100%). These high transmittance values along with

the optically clear appearance of SMEDDS

dispersion confirmed the finer globule size of theformed_SMEDDS.


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Pol et al Pg. 95

Table 3: Emulsification efficiency of various non-ionic surfactants

Surfactants % Transmittance values with given Cosurfactants

PEG 400 Labrasol Transcutol P

Tween 80 97.59 0.04 98.94 0.08 99.09 0.04

Gelucire 44/14 89.26 0.54 92.115 0.88 96.625 0.54Solutol HS 15 100.1 0.13 100.082 0.54 100.43 0.13Cremophor EL - - 99.72 0.09

Construction of pseudo-ternary phase

diagrams

Pseudoternary phase diagram is a useful approachto exemplify the various interactions that occur onvarying the components used in the formulation of

microemulsions. These pseudoternary phase

diagrams can be modified further by plotting thecomponents of SMEDDS except water, whose

quantity is kept constant throughout theexperiment by diluting the preconcentrates with

constant amount of distilled water.

Table 4: Combinations evaluated by pseudo-ternary phase diagrams.

Formula Surfactant Cosurfactant Combination

A Tween 80 Labrasol Tween 80 Labrasol- Peppermint oil

B Solutol HS 15 Labrasol Solutol HS 15 Labrasol- Peppermint oilC Tween 80 Transcutol P Tween 80 -Transcutol P-Peppermint oil

D Solutol HS 15 Transcutol P Solutol HS 15 Transcutol P- Peppermint oilE Cremophor EL Transcutol P Cremophor EL-Transcutol P- Peppermint oil

F Tween 80 PEG 400 Tween 80- PEG 400- Peppermint oilG Solutol HS 15 PEG 400 Solutol HS 15- PEG 400- Peppermint oil

Initially, optimization studies were performed with

the help of phase diagram. The changes inbehavior of the systems for phase separation and

for drug precipitation were evaluatedmacroscopically and microscopically. Various

phase diagrams depicted in Figs. 4 to 7 reflectedthe influence of drug content and respectivecombinations of surfactant and cosurfactants.

Although PEG 400 showed best solubilizingcapacity for ACF, the region of microemulsion was

found to decrease for systems containing PEG 400as the cosurfactant. The systems with Transcutol P

as cosurfactant showed larger microemulsionregion but precipitation of ACF was observed

eventually in all combinations except combinationcontaining Cremophor EL-Transcutol P-

Peppermint oil [Fig.7]. The combinations ofsurfactants with Labrasol gave more stable

systems with respect to drug precipitation. Butsince globule sizes for systems in combination Awere higher than 150 nm (which was selected as

the criteria for globule size) they were rejected.Microemulsion regions for the combinations B and

E were found satisfactory as depicted in the phasediagrams (Fig. 4 and 5). The systems were then

evaluated along with their placebo systems for theeffect of drug on microemulsion region formation.

Location of the solubilized drug in microemulsion

systems depends on the hydrophobicity and

structure of the solute. Enhanced drug solubility in

microemulsion and micellar systems usually arisesfrom the solubilization at the interface. The solute

associated with interface, in turn, may affect thesize and shape of the microemulsion droplets.

Phase diagrams studies indicated a remarkableinfluence of ACF on globule size of systems.Incorporation of ACF in peppermint oil led to a

considerable reduction in the area ofmicroemulsion formation (Fig. 5 and 7). Due to its

low aqueous solubility, ACF is likely to participatein the microemulsion formation by orienting at the

interface. The reduction in the area ofmicroemulsion formation could be due to ACF-

influenced interaction of surfactant and co-surfactant with oil. The phase diagram studies led

to the selection of formulations FA containingSolutol HS 15: Labrasol: Peppermint oil

combination in 40:30:30 proportions. Theselections were made on the basis of lowersurfactant concentrations, high content of oily

phase, high drug loading and globule size lessthan 150 nm. These conditions were selected

based on a hypothesis that if the concentration ofsurfactant is high, drug concentration at the

interphase would probably be greater andchances of drug precipitation may be more as

compared to systems containing high

concentration of oily phase.


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Fig.4: Pseudo ternary phase diagrams ofcombination B

Fig.5: Pseudo ternary phase diagrams ofcombination B without drug

Fig.6: Pseudo ternary phase diagrams of

combination E

Fig.7: Pseudo ternary phase diagrams of

combination E without drug

The outer parallelogram indicates the area, whichwas explored for locating microemulsificationregion. The filled blue region indicates the region

in which microemulsions of desired size wereobtained.

Influence of drug loadingEffect of drug loading on globule size and

polydispersity index of microemulsions generatedfrom optimized formulations is shown in Fig.8. The

formulations containing dose higher than 110 mgwere found to show an increase of 25 nm in the

globule size Fig.8) and drug precipitation over a

period of 12 h.

Influence of oil contentThe effect of increase in the oil concentration onglobule size of selected systems is shown in

Figs.8. As depicted in Fig.8, increase in thecontent of oily phase upto 250 mg in system was

not found to show a considerable change inglobule size of the resulting microemulsions. Thiscould be explained as, when the concentration of

oil was increased, the concentrations of surfactantand cosurfactant were probably insufficient to

reduce the surface tension at the interphase,resulting in separation of non- emulsified oil

droplets and thus coalescence of oil droplets and

phase separation.


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Pol et al Pg. 97

(a) (b)Fig. 8: (a) Effect of drug loading on globule size# and P.I. of optimized formulations FA (b) Effect

of oil content on globule size and P.I of system (n=3).

Characterization

AppearanceThe filled capsules showed no signs of leakage,discoloration, pinholes and shell distortion. ACF

loaded SMEDDS appeared as clear, transparent,

homogenous liquids at room temperature. Notraces of particulate matter nor drug precipitation

were observed.

Fig. 9: ACF capsules and process of formulation release and self-emulsification from capsule.

Uniformity of weight

None of the capsules were found to deviate fromthe average capsule by more than 7.5 % and were

found to comply with I.P96 standards foruniformity of weight for capsules.

Drug Content

The drug content of various self-microemulsifyingformulations was found to be within the range of

99-101% which was in agreement withpharmacopoeial specifications.

Self-microemulsification efficiency

Formulations were found to release the contents

immediately upon rupturing and self-emulsifywithin a minute. Fig.9 shows process of drugrelease and self-emulsification from capsule.

Globule size analysis

The results of globule size of the formulations (withand without ACF) were found to be 25.6 2.34 and91.9 10.58 nm respectively. The effect of drug

incorporation in SMEDDS was found to be

influenced by the drug-system physicochemicalproperties. After dilution of preconcentrates withvarious aqueous phases, the resulting

microemulsions were found to be clear,transparent and appeared like homogenous

single-phase liquids.

pH determination

ACF incorporation into SMEDDS lowered the pH ofthe systems towards acidic side; this change maybe attributed to the acidic nature of the drug. After

the dilutions of the preconcentrates with distilledwater, the pH values were found to increase. This

may be probably due to encapsulation of majorquantity of drug into microemulsion and so

decrease in acidic nature of the systems.

Dilution test

The ability of a microemulsion to be diluted

without any drug precipitation is essential for itsuse as a drug delivery vehicle since, afteradministration, it will almost certainly be diluted

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

0

20

40

60

80100

120

140

160

180

50 75 100 115 130

Polydispersity

index

Meanglobulesizeinnm

ACF dose in mg

Globule size of FA

P.I of FA

0.95

1

1.05

1.1

1.15

1.2

0

30

60

90

200 225 250 350

Polydispers

ityindex

Meanglobule

sizeinnm

Content of peppermint oil in mg


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Pol et al Pg. 98

by body fluids. These studies were performed tostudy the robustness of the formulations towards

different media (varying in pH & electrolytecontent) simulating gastric tract conditions. After

dilution, the resulting microemulsions were foundto remain clear, transparent and appeared like

homogenous single-phase liquids. All thepreconcentrates were found to be dispersed

within one minute. In addition, the compositionand pH of the aqueous phase was found to have no

effect on the properties of microemulsions and didnot show any separation or drug precipitation till 8

hr. The ACF SMEDDS showed fairly similar meanglobule size (within range of 50100 nm) when

diluted with various media differing in pH andelectrolyte concentration. In general globule size

of microemulsions was found to remain stable for 4hr. (Fig. 10). Thus from these studies it can be

predicted that ACF SMEDDS could retain itsstability after dilutions in GI tract.

Fig. 10: Effect of pH and electrolytes of aqueous phase on globule size (nm) ## Globule size (nm) expressed as mean, (n = 3) where relative standard deviation was < 10 %.

Zeta potential measurement

The electrical surface charge of the droplets is

produced by the ionization of interfacial film-forming components. The surface potential and the

resulting Zeta potential of emulsion droplets willdepend on the extent of ionization of theemulsifying agents. Zeta potential of the system

was found to be -47.77 7.64 mV and 8.04 4.3 inpH 1.2 and 6.8 respectively, thus indicating

stability of developed smedds after dilution ingastric environment. Elecrtophoretic mobility was

found to be -3.7 2.6 and 0.63 0.34 in pH 1.2 and

6.8 respectively.

Transmission electron microscopy (TEM)

The microemulsion appeared dark and thesurroundings were bright (data not shown), a

positive image was seen using TEM. In addition,the morphology of the droplet was spherical and

there was no evidence of ACF precipitation ineither the oil phase or the aqueous phase.

Thermodynamic stability

Centrifugation and freeze-thaw cycling areaccelerated tests used to determine the stability of

microemulsions under stress conditions. All theformulations were found to remain stable after

centrifugation and freeze-thaw cycle process andno phase separation or drug precipitation wasobserved. Particle size and polydispersity

remained unaffected after freeze-thaw process,thus confirming the stability of developed

microemulsions.

In vitro release profile

The dissolution profile of ACF from variousoptimized SMEDDS, marketed (Movon Capsule

100mg) and plain ACF was determined. Theselection of the particular medium for studying in

vitro release profile of the drug was based on thesolubility studies results reported in literature. The

in vitro drug release profile of the ACF in 0.1 N HCl+ 1 % SLS from various formulations are shown inFig. 11. The dissolution rate of ACF from the

developed SMEDDS was found to be significantlyhigher than that from the marketed formulation.

The results indicated a fasterin-vitro release of thedrug from the developed formulations (T 80% = 5

mins) as compared to that from marketedformulations (T 80% = 45 min). The plain drug

released 72.76% of drug in one hour whereas themarketed formulation and the developed

formulations exhibited a release of 81.774 % and99.23 to 100.17 % respectively.

0

20

40

6080

100

120

140

160

180

0 1 2 4 8

GlobuleSize(nm)

Time (Hr)

Water pH 1.2 pH 3 pH 6.8 Ringer Solution


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Pol et al Pg. 99

Fig. 11:In vitro

release profiles of differentformulations of ACF in 0.1N HCl containing 1%SLS

Evaluation of Anti-Inflammatory Activity in ratpaws edema

Carrageenan induced edema in rat is a well

established model used experimentally toevaluate anti-inflammatory activity of any

drug/extract from natural/synthetic origin. Theedema develops in three distinct phases. The first

phase involved release of histamine, whereas inthe second phase kinin and bradykinin are

released, and the last phase in manifested byinvolvement of prostaglandins. Most anti

inflammatory drugs including ACF are effective atthis phase of edema formation [18]. The anti-

inflammatory activity of plain ACF, plaindiclofenac and the developed SMEDDS

formulations over a period of 7.5 hours is depictedin Fig. 12.

A significant difference (P < 0.05) in the percentinhibition values was obtained between the

developed ACF SMEDDS and plain ACF at 4 hr.The percentage inhibition of edema by developedSMEDDS was comparable to that of plain

diclofenac while placebo formulation also showedinhibition in inflammation during first half of the

study. The ACF SMEDDS and plain diclofenacshowed inhibition of 80 7.30 % and 88.01 2.97

respectively after 4 hr of treatment againstcarrageenan induced paw edema at the dose of

10mg/kg. These observations may be attributed to

the increase in absorption of ACF from theformulated SMEDDS, indicating a possibility ofincreased bioavailability and synergistic activity

with peppermint oil. As volatile oils such as mintoils have shown to exhibit in vivo anti-

inflammatory activity.

A statistically insignificant difference was

observed in the anti-inflammatory activity of theformulation containing lower dose of drug (FA-70)

and that containing 100 mg of ACF (FA-100). Thus,it could be concluded that reduction of dose could

be effectively tried in ACF SMEDDS without

significant reduction in the anti-inflammatoryactivity.

(a) (b)Fig. 12: Effect of ACF SMEDDS on rat paw edema wherein (a) Comparative graph representing

effect of ACF formulations and plain ACF and Diclofenac on paw edema induced by carageenan inSprague dawley rats [FA-70 is SMEDDS with ACF 70mg and FA-100 is SMEDDS with ACF 100mg]and (b) Comparative graph of percent inhibition ( * P < 0.01

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 5 10 15 20 30 45 60

%Drugrelease

Time in min

F A ( 100 mg)

Marketed formulation

Plain drug

0

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30

40

50

60

70

80

90

100

Placebo ACFSMEDDS

70

ACFSMEDDS

100

Plain ACF Plaindiclofenac

Pe

rcentageInhibition

3 Hr 4 Hr

*

-5

5

15

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35

45

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75

0 1 2 3 4 5 6 7 8

Percentage

Time (hr)

vehicle control Blnk A

F A-70 F A-100* *


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Pol et al Pg. 100

Evaluation of gastric ulcerogenicity

The gastric ulcer scores of developed self-microemulsified systems were found to be

significantly lower than the marketed formulation(Fig. 13) of ACF (P < 0.05). The formulationexhibited the lowest score (0.670.577), as

compared to other groups whereas the highestscore was observed by the marketed formulation

(5.0 0.07) Fig.16. The mean score for the degreeof injury produced by plain ACF was 3.67 1.15 (n

= 6). The formulation exhibited a significantdifference in the score index as compared to that

of plain ACF. Thus, it could be concluded that thedelivery of the drug as a self-microemulsified

system resulted in reduction in the ulcerogenicpotential of the drug. It is reported that crystals of

NSAIDs being poorly soluble in gastric acidremain in contact with the stomach wall for a

longer period of time, resulting in a dangerouslyhigh local concentration. This leads to local

irritation of the stomach wall and to ulceration. Ingeneral, it is expected that the drug delivered in amicroemulsion vehicle is in a solubilized form,

thus resulting in accelerated absorption.Moreover, when delivered as SMEDDS, the drug

may probably not come in direct contact with thestomach wall, leading to decreased ulceration.

The incorporation of ACF in SMEDDS, thusprovided better protection against GI tract

ulceration as compared to the marketed

formulation [18,19,20].

Fig. 13: Effect of various treatments on degree of injury to stomach

CONCLUSION

In the present investigation, improvement in

aqueous solubility of Aceclofenac was achieved by

incorporation into SMEDDS. Use of Peppermint oil,a terpene based solubilizers was explored for

preparation of ACF SMEDDS. ACF SMEDDSexhibited excellent stability in different pH mediaand electrolyte content. In vitro dissolution study

demonstrated a significant improvement in thedissolution profile of ACF. The developed

SMEDDS were found to exhibit less GI tract

toxicity and showed superior anti inflammatory

action compared to plain drug as well asdiclofenac.

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0

1

2

3

4

5

6

VehicleControl

Placebo ACFSMEDDS 70

ACFSMEDDS 100

Plain ACF PlainDiclofenac

MarketedFormulation

DegreeofInjury


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How to cite this article

APA style

Pol, A. S., Patel, P. A., & Hegde, D. (2013). Peppermint oil based drug delivery system of

aceclofenac with improved anti-inflammatory activity and reduced ulcerogenecity.InternationalJournal of Pharma Bioscience and Technology, 1(2), 89101.

Elsevier Harvard style

Pol, A.S., Patel, P.A., Hegde, D., 2013. Peppermint oil based drug delivery system of

aceclofenac with improved anti-inflammatory activity and reduced ulcerogenecity. Int. J. Pharm.Biosci. Technol. 1, 89101.

Vancouver StylePol AS, Patel PA, Hegde D. Peppermint oil based drug delivery system of aceclofenac with

improved anti-inflammatory activity and reduced ulcerogenecity. Int. J. Pharm. Biosci. Technol.2013;1(2):89101.

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