Ondanstetron SNEGs

(This is a sample cover image for this issue. The actual cover is not yet available at this time.)

This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution

and sharing with colleagues.

Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party

websites are prohibited.

In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information

regarding Elsevier’s archiving and manuscript policies areencouraged to visit:

http://www.elsevier.com/copyright

http://www.elsevier.com/copyright

Author's personal copy

Colloids and Surfaces B: Biointerfaces 101 (2013) 414– 423

Contents lists available at SciVerse ScienceDirect

Colloids and Surfaces B: Biointerfaces

jou rna l h om epa g e: www.elsev ier .com/ locate /co lsur fb

Development of solid self-nanoemulsifying granules (SSNEGs) of ondansetronhydrochloride with enhanced bioavailability potential

Sarwar Bega,c, Sidharth Sankar Jenaa, Ch Niranjan Patraa, Mohammad Rizwanb,∗, Suryakanta Swaina,J. Sruti a, M.E. Bhanoji Raoa, Bhupinder Singhc

a Department of Pharmaceutics, Roland Institute of Pharmaceutical Sciences, Khodasingi, Berhampur, Orissa, Indiab Formulation Research, Wockhardt Research Center, Aurangabad, Maharashtra, Indiac University Institute of Pharmaceutical Sciences (UGC Centre of Advanced Studies), Panjab University, Chandigarh, India

a r t i c l e i n f o

Article history:Received 20 April 2012Received in revised form 22 June 2012Accepted 25 June 2012Available online xxx

Keywords:SNEDDSHepatic first-pass effectPorous carriersSelf-nanoemulsifyingPharmacokinetics

a b s t r a c t

The current work aims to prepare the solid self-nanoemulsifying granules (SSNEGs) of ondansetronhydrochloride (ONH) to enhance its oral bioavailability by improving its aqueous solubility and facilitatingits absorption though lymphatic pathways. Preformulation studies including screening of excipients forsolubility and pseudoternary phase diagrams suggested the suitability of Capmul MCM as lipid, Labrasolas surfactant, and Tween 20 as cosurfactant for preparation of self-emulsifying formulations. Prelimi-nary composition of the SNEDDS formulations were selected from the phase diagrams and subjected tothermodynamic stability studies and dispersibility tests. The prepared liquid SNEDDS formulations werecharacterized for viscosity, refractive index, droplet size and zeta potential. The TEM study confirmedthe formation of nanoemulsion following dilution of liquid SNEDDS. The optimized liquid SNEDDS weretransformed into free flowing granules by adsorption on the porous carriers like Sylysia (350, 550, and730) and NeusilinTM US2. Solid state characterization employing the FTIR, DSC and powder XRD studiesindicated lack of any significant interaction of drug with the lipidic and emulsifying excipients, and porouscarriers. In vitro drug release studies indicated faster solubilization of the drug by optimized SSNEGs (over80% within 30 min) vis-à-vis the pure drug (only 35% within 30 min). In vivo pharmacokinetic studies inWistar rats observed significant increase in Cmax (3.01-fold) and AUC (5.34-fold) using SSNEGs comparedto pure drug, whereas no significant difference (p > 0.1) was observed with the liquid SNEDDS. Thus, thepresent studies ratify the bioavailability enhancement potential of SSNEGs of ONH prepared using porouscarriers.

© 2012 Elsevier B.V. All rights reserved.

1. Introduction

Poor aqueous solubility of new drug entities is today con-sidered as a formidable challenge for pharmaceutical scientist,which is now considered as an area of prime importance in thefield of biomedical research. Approximately one-half of the newmolecular entities (NMEs) synthesized in pharmaceutical R&Dsemploying with advanced techniques like combinatorial chemistryand computer-aided drug design (CADD) suffer from poor solubil-ity and bioavailability [1,2]. To overcome such problems, variousformulation approaches have been undertaken to improve oralbioavailability including surfactants [3], cyclodextrin complexes[4], solid dispersions [5], micronization and nanosizing [6], perme-ation enhancers [7], supercritical technology [8], gastroretentive

∗ Corresponding author. Tel.: +91 8087766453.E-mail address: rizwan [email protected] (M. Rizwan).

systems [9], nanosuspensions [10], dendrimers [11], carbon nano-tubes [12] and lately, lipid-based formulations [13].

Ondansetron hydrochloride (ONH) is a 5-HT3 receptor antago-nist, primarily used as first-line drug for the management of nauseaand vomiting associated with cancer chemotherapy, chronic med-ical illness, gastroenteritis and post-operative states [14]. The drugis poorly water soluble and possesses intermediate value of logP (i.e., 2.4) [15]. Ondansetron exhibits low (i.e., 45%) and incon-sistent bioavailability, potentially due to high hepatic first-passmetabolism and high P-gp efflux, besides the inadequate aque-ous solubility [16,17]. The myriad drug delivery systems of ONHdeveloped so far have yielded limited fruition in oral bioavailabilityenhancement [18,19].

Self-nanoemulsifying drug delivery systems (SNEDDS) haverecently gained wide acceptance due to robust formulationperspectives, practical enhancement of solubility and of oralbioavailability of drugs through lymphatic pathways [20]. Theseare pre-concentrates containing isotropic mixture of oils, surfac-tants and cosurfactants. They facilitate the dissolution of various

0927-7765/$ – see front matter © 2012 Elsevier B.V. All rights reserved.http://dx.doi.org/10.1016/j.colsurfb.2012.06.031


S. Beg et al. / Colloids and Surfaces B: Biointerfaces 101 (2013) 414– 423 415

poorly water-soluble drug candidates by in situ solubilization inlipidic components [20–22]. They spontaneously emulsify whenexposed to aqueous media or gastrointestinal (GI) fluids to form astable o/w emulsion with nanometric droplet size ranging between20 and 200 nm. Further, they also provide distinct improvement inbioavailability for lipophilic drugs exhibiting dissolution rate lim-ited absorption and poor permeation [23].

The conventional liquid SNEDDS, however, have limited accep-tance owing to their major drawbacks, like precipitation of drugdue to potential interaction of volatile cosolvents with soft gelatincapsule shells and GI irritation due to high level of surfactant in theformulations [19]. To overcome such problems, the solid SNEDDSare developed as the technological innovations, which incorporateliquid or semisolid ingredients into powders employing diversesolidification techniques like spray drying [24], melt granulation[25], extrusion–spheronization [26], eutectic mixing and nanopar-ticle technology [27]. The solid SNEDDS are relatively more robustformulations with high stability, improved patient compliance andsimple manufacturing [20,24,26]. Such solid SNEDDS can furtherbe formulated into free flowing powders, granules, pellets, tablets,solid dispersions, microspheres and nanoparticles [28–30]. Besides,limited volume of literature is also available describing the use ofporous carriers like cross-linked porous silicon dioxide (SylysiaTM

320, 350, 550, 750), magnesium aluminum silicate (NeusilinTM

US2) and microporous calcium silicate (FloriteTM RE) for adsorptionof liquid self-emulsifying formulations and transforming them intosolid SNEDDS [31–33].

Attempts, therefore, were made to prepare the SSNEGs of poorlywater soluble drug, ONH, using porous carriers like SylysiaTM (350,550, and 730) and NeusilinTM US2 to enhance its aqueous solubility,and oral bioavailability by possible avoidance of hepatic first-passeffect, inhibition of P-gp efflux and enhanced absorption throughlymphatic pathways.

2. Materials and methods

2.1. Materials

ONH was generously gifted by M/s Aurobindo Pharma, Hyder-abad, India. Labrasol, Labrafac PG and Labrafil M were gifted byM/s Gattefosse, Saint-Priest Cedex, France. Captex 200P, Captex355 and Capmul MCM were provided by M/s Abitec, Janesville,WI, USA. Cremophor RH40 was obtained from M/s BASF, Lud-wigshafen, Germany. Different grades of Sylysia (350, 550 and 730),and NeusilinTM US2 were generously provided by M/s Fuji chemi-cals, Toyama, Japan, and by M/s Gangwal Chemicals, Mumbai, India,respectively. Deionized water was used for study obtained fromMilli-Q-water purification system M/s Millipore, Massachusetts,USA. All other reagents and solvents used were of analytical reagentgrade.

2.2. Methods

2.2.1. Solubility studiesSolubility of ONH was determined in various excipients viz. nat-

ural oils (coconut oil, palmoline oil, olive oil, sesame oil, arachisoil, castor oil, and neem oil), medium chain triglycerides (Cap-tex 200, Captex 355 and Capmul MCM), surfactants (Labrasol,Labrafil, Labrafac and Brij 35) and cosurfactants (Polypropylene gly-col, Tween 20, Tween 80, PEG 200, PEG 400 and PEG 600). Excessamount of ONH was added to 2 mL of each excipient in sealedvials and vortex-mixed (Vortex mixer, Remi, Mumbai, India). Thesealed vials were stirred in water bath (Julabo SW23, Allentown,PH, USA) at 37 ± 0.5 ◦C for 72 h to attain equilibrium. All sam-ples were centrifuged at 3000 rpm (402.48 × g) for 15 min using

laboratory centrifuge (Remi, Mumbai, India). The supernatant wasfiltered through 0.45 �m membrane filter (Millipore, Mumbai,India), suitably diluted with methanol, and analyzed spectropho-tometrically at a �max of 310 nm using a double beam UV-VISspectrophotometer (Shimadzu-1800, Japan).

2.2.2. Pseudo-ternary phase diagrams2.2.2.1. Selection of surfactants and cosurfactants (Smix) ratios. Theexcipients, viz. oil, surfactant and cosurfactant, selected from thesolubility studies were used to construct the pseudo-ternary phasediagrams employing water titration method. The pseudo-ternaryphase diagrams were prepared to identify the Smix ratios, wheremaximum nanoemulsion region forms. Various Smix ratios wereprepared using different proportions of surfactant and cosurfactantto fulfill HLB value requirement (12–16) which favors nanoemul-sion formation.

2.2.2.2. Construction of pseudo-ternary phase diagrams. Differentratios of oil to surfactant/cosurfactant mixture (Smix) were selected,ranging between 1:9 and 9:1, to delineate the boundaries ofnanoemulsion region. The homogenous mixture of oil and Smixwas subjected to aqueous titration with the addition of 5 mL ofwater in each step, and was visually observed. The amount of waterat which transparency-to-turbidity transition occurs was derivedfrom the weight measurements. The generated sample, which wasclear or slightly bluish in appearance, was taken as the nanoemul-sion. To determine boundaries of nanoemulsion, the values of oiland Smix ratio were calculated from the weight measurements.Pseudoternary phase diagrams were constructed using PROSIMsoftware (STRATEGE, Cedex, France).

2.2.3. Formulation of liquid SNEDDSDifferent liquid SNEDDS formulations were prepared by select-

ing the concentration of oil and Smix from pseudoternary phasediagrams, as presented in Table 1. The SNEDDS were pre-pared by simple admixture of drug with oil with mixturesof surfactant/cosurfactant using vortex mixer at an ambienttemperature.

2.2.4. Characterization of liquid SNEDDS2.2.4.1. Dispersibility test. One mL of liquid SNEDDS from each for-mulation was taken, and mixed with 500 mL of distilled water at37 ◦C with constant stirring at 50 rpm. The SNEDDS were observedfor the formation of stable nanoemulsions. The nanoemulsionsformed were visually observed for phase clarity, self-emulsificationtime (SEF time) and rate of emulsification.

2.2.4.2. Thermodynamic stability studies. The liquid SNEDDS formu-lations were subjected to heating-cooling test using six refrigeratorcycles at 45 ◦C and 4 ◦C temperatures separately for 48 h in an incu-bator (Remi, Mumbai, India). Formulations, which were found tostable during heating cooling cycles, were further centrifuged at3500 rpm (402.48 x g) for 30 min. The stable liquid SNEDDS weresubjected again to freeze-thaw cycles (n = 3) at −21 ◦C and 25 ◦C,respectively, and stirred continuously.

2.2.4.3. Viscosity. Viscosity of the selected liquid SNEDDS weredetermined by placing 1 mL of undiluted formulation in theviscometer (R/S CPS Plus, Brookfield Engineering Lab. Inc., Mid-dleboro, MA) using spindle #C 50-1 at 25 ± 0.5 ◦C. The spindle(50 mm diameter) was operated at a speed 70 rpm with shearstress of 413 rpm, keeping the wait time as 15 min. Finally,the developed shear rate was noted in terms of centipoise(cps).


416 S. Beg et al. / Colloids and Surfaces B: Biointerfaces 101 (2013) 414– 423

Table 1Composition of the liquid SNEDDS formulations.

Components (% w/w) F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12

ONH 1 1 1 1 1 1 1 1 1 1 1 1Capmul MCM 20 25 27 30 20 25 27 30 20 25 27 30Labrasol 39.5 37 36 34.5 26.33 24.66 24 23 31.6 29.6 28.8 27.6Tween 20 39.5 37 36 34.5 52.66 49.33 48 46PEG 600 47.4 44.4 43.2 41.4Smix ratio 1:1 1:1 1:1 1:1 1:2 1:2 1:2 1:2 2:3 2:3 2:3 2:3

2.2.4.4. Refractive index. Refractive index was determined usingAbbe’s refractrometer (Nirmal International, Mumbai, India) byplacing a drop of undiluted liquid SNEDDS.

2.2.4.5. Droplet size analysis and zeta potential. The liquid SNEDDSwere diluted with deionized water at 25 ◦C under gentle agitation.The droplet size distribution and zeta potential were determinedusing dynamic light scattering principle (Malvern Zetasizer, NanoZS-90, Worcestershire, UK). The values of mean droplet size andzeta potential were recorded.

2.2.4.6. Transmission electron microscopy (TEM). The TEM analysisof liquid SNEDDS was performed for morphological characteriza-tion and visualization of emulsion droplets. The liquid SNEDDSformulation was diluted with deionized water (1:25) and mixed bygentle shaking. A drop of sample obtained after dilution was placedon copper grids, stained with 1% phosphotungstic acid solution for30 s, and finally kept under electron microscope (Philips Tecnai 12,Eindhoven, Netherlands) to visualize the particle morphology.

2.2.5. Formulation of SSNEGsThe optimized liquid SNEDDS was transformed into free flowing

granules using various colloidal porous carriers as adsorbents likeSylysia (350, 550, 730) and NeusilinTM US2. The liquid SNEDDS for-mulation was poured onto porous carriers placed in a small chinabowl, mixed well for 5 min to obtain a homogeneous mass. Themass was subsequently passed through a sieve (#BSS 22) and filledinto the size “0” hard gelatin capsules (Capsugel, Mumbai, India).

2.2.6. Optimization and characterization of SSNEGsThe SSNEGs prepared using different porous carriers were

optimized based on their oil adsorption capacity, micromeriticproperties, in vitro drug release and retention of self-emulsificationproperty. Oil adsorption capacity was determined by slow additionof liquid SNEDDS formulations to adsorb onto the porous carri-ers until these solidified, and by estimating their drug content.Important micromeritic properties of granules like bulk density,tap density, angle of repose, Carr’s index and Hausner’s ratiowere determined using standard procedures. In vitro drug releasefrom SSNEGs was determined by withdrawing periodic aliquots ofsamples during dissolution and analyzing the same spectrophoto-metrically at 310 nm. The samples were also observed under TEMfor formation of nanoemulsion, if any.

2.2.7. Comparative in vitro drug release studiesIn vitro drug release studies were finally carried out for opti-

mized SSNEGs and optimized liquid SNEDDS vis-à-vis marketedproduct (Zofran® ODT, GlaxoSmithKline, India) and pure drug, eachcontaining 8 mg of ONH. The studies were conducted out in 900 mLof simulated gastric fluid (SGF) at 75 rpm and 37 ± 0.5 ◦C using USPII apparatus (Electrolab, Mumbai, India) [34]. At predeterminedtime intervals (5, 10, 15, 30, 45, 60, 90 and 120 min), aliquots ofsamples (5 mL) were collected and filtered through 0.45 �m mem-brane filter, suitably diluted and analyzed spectrophotometricallyat 310 nm. The in vitro dissolution data were analyzed using MS-Excel spreadsheet and cumulative percentage drug release was

plotted against time (h). Further, the values of dissolution efficiencyat 15 min (DE15 min) and mean dissolution time (MDT) were alsodetermined for the test formulations using standard algorithms[23].

2.2.8. Drug content estimationThe liquid SNEDDS and SSNEGs containing ONH, each containing

8 mg of ONH, were suitably dispersed in 100 mL of SGF in a volumet-ric flask. The samples were mixed gently, sonicated (Remi, Mumbai,India) to extract ONH completely, and centrifuged at 3000 rpm(402.48 × g) for 15 min to separate undissolved excipients. Thesupernatant was filtered through 0.45 �m membrane filter (Mil-lipore, Mumbai, India), suitably diluted and analyzed using UV-VISspectrophotometer (Shimadzu 160A, Japan) at a �max of 310 nm.The experimental studies were performed in triplicate.

2.2.9. In vivo pharmacokinetic studiesThe experiments were conducted as per the Committee for

prevention, control and supervision of experimental animals (CPC-SEA) guidelines. Wistar rats (200–250 gm) of either sex were keptunder standard laboratory conditions at 25 ± 2 ◦C temperature and55 ± 5% RH. The animals were housed in polypropylene cages, sixper cage with free access to standard diet (Lipton feed, Mumbai,India) and water ad libitum. The pharmacokinetic studies were car-ried out in accordance with protocol approved by the InstitutionalEthics Committee at Roland Institute of Pharmaceutical Sciences,Berhampur, Odisha, with protocol number RIPS/IAEC/46/2011. Therats were divided into five groups with six animals in each group.Control group received distilled water, and other treatment groupsreceived suspension of pure drug, marketed preparation (Zofran®

ODT), optimized liquid SNEDDS and SSNEGs, each containing 8 mgof ONH. Rats were fasted overnight before oral administration ofdifferent formulations using a 5 mL oral feeding needle attachedwith a cannula. Oral dose for rat was calculated after taking intoconsideration of surface area ratio of rat to that of human [35,36].After administration of different test formulations, rats were anaes-thetized using diethyl ether. Blood samples (0.5 mL each) werewithdrawn from the tail vein in microcentrifuge tubes containingheparin as an anticoagulant. Blood samples collected were mixedwith anticoagulant and centrifuged at 5000 rpm (1118 × g) for20 min. The supernatant plasma samples obtained were mixed with0.5 mL of ethyl acetate and allowed to evaporate. The dried sampleswere reconstituted with chloroform:methanol mixture (9:1%, v/v)and stored frozen at −21 ◦C in eppendorff tubes until analyzed. ONHwas analyzed in plasma employing a modified RP-HPLC method[37]. The mobile phase was 0.7 M sodium perchlorate-acetonitrile(50:50, %v/v) and the flow-rate was 0.5 mL/min. The chromato-graphic separation was achieved using Capacel Pak C18 column(Shiseido, Tokyo, Japan) with 250 × 4.6 mm i.d. and 5 �m particlesize, coupled with UV-Vis detector at 210 nm, on a binary pump RP-HPLC instrument (Shimadzu, Tokyo, Japan). The extracted plasmasamples were injected by means of a Rheodyne injector fitted witha 20 �L loop and data acquisition was controlled by ShimadzuClass-VP 5.032 software. Pharmacokinetic parameters like Cmax,tmax, t1/2, Ka, AUC0−t, AUMC0−t and MRT0−t were determined fromplasma concentration–time profile for different test formulations.



The pharmacokinetic profiles of test formulations (liquid SNEDDSand SSNEGs) were compared with those of pure drug suspensionand Marketed brand (Zofran® ODT). Statistical analysis was carriedout by paired t-test to determine the significant difference betweenthe test groups for any change in pharmacokinetic parameters. Therelative bioavailability was calculated using Eq. (1):

%F = AUC(test)AUC(std)

× Dose(std)Dose(test)

(1)

2.2.10. Fourier transformed infrared (FTIR) spectroscopyFTIR spectroscopic studies were employed to characterize the

possible interactions, if any, between the drug and excipients. TheFTIR spectra of samples of pure drug, physical mixture of drug withself-emulsifying excipients and SSNEGs were recorded using KBrdisc using an FT-IR spectrophotometer (Shimadzu, Japan).

2.2.11. Differential scanning calorimetry (DSC)DSC thermograms of pure drug, physical mixture (1:1) of drug

with self-emulsifying excipients, porous carriers, optimized liquidSNEDDS and SSNEGs were carried out using Pyris-6-DSC Ther-mal analyzer (PerkinElmer, Tokyo, Japan). The liquid samples weresealed in the heat-resistant aluminium pans and lid was crimpedon its surface by pressing under pellet press. The sample and ref-erence pans were kept in the heating chamber, heated from 30 to300 ◦C with temperature rise at a rate of 10 ◦C/min, and DSC spectrawere recorded.

2.2.12. Powder XRD studiesPowder XRD studies were carried out for solid state char-

acterization including powder morphology and crystallographicstructure of pure drug and SSNEGs. The diffraction pattern of ONHand SSNEGs were recorded by X-ray diffractometer (Philips PW17291, Philips, The Netherlands) using Ni-filtered, Cu kV radiation,at a voltage of 40 kV and a 25 mA current. The scanning rate waskept between 10◦ and 40◦ angles with an increment of 1◦ min−1

over 2� range.

2.2.13. Accelerated stability studiesThe optimized SSNEGs in size “0” capsules were sealed

HDPE bottle and subjected to accelerated stability studies at40 ± 2 ◦C/75% ± 5% RH upto three months. The SSNEGs capsuleswere evaluated for disintegration time, SEF time, droplet size afternanoemulsification, percentage drug release in 15 min (%DR15 min),and MDT at specified time points (0, 1, 2 and 3 months). For estima-tion of shelf-life, the SSNEGs capsules in HDPE bottle were stored at30 ± 0.5 ◦C, 40 ± 0.5 ◦C and 50 ± 0.5 ◦C temperature upto a period ofthree months. Samples were withdrawn after specified time inter-vals (0, 1, 2 and 3 months), concentration and log concentrationof ONH remained was analyzed. Order of reaction in which drugdegradation occur was estimated. The reaction rate constant (K) forthe degradation was measured from slope of lines at each elevatedtemperature using Eq. (2), and an Arrhenius plot was constructed(i.e., plot of log K at various elevated temperatures against the recip-rocal of absolute temperature). From the plot, K value at 25 ◦C wasdetermined and used for prediction of shelf-life by substituting inEq. (3).

Slope = −K

2.303(2)

t90 = 0.1052K25

(3)

3. Results

3.1. Solubility studies

Amongst the various oils, surfactants and cosurfactants investi-gated for equilibrium solubility studies viz. Capmul MCM, Captex200, Captex 355, olive oil, arachis oil, sesame oil, Labrasol, Labrafil,Labrafac, Tween 20, Tween 80, Polypropylene glycol, PEG 200, PEG400 and PEG 600, the highest solubility of ONH was observed inCapmul MCM (32 ± 3.2 mg/mL), Labrasol (31.1 ± 1.8 mg/mL), PEG600 (35.3 ± 2.3 mg/mL) and Tween 20 (28.5 ± 2.0 mg/mL) (data notshown). Hence, they were selected for construction of pseudo-ternary phase diagrams and further studies.

3.2. Pseudo-ternary phase diagrams

The pseudo-ternary phase diagrams of surfactant, cosurfactantand oil were plotted, each of them represents an apex of the tri-angle [38]. The ternary phase diagrams with Smix ratios of 1:1, 1:2and 2:3 for Labrasol:Tween 20 showed the maximum region fornanoemulsion(s) using Capmul MCM as the oil phase (Fig. 1).

3.3. Selection of liquid SNEDDS

The prototype liquid SNEDDS formulations were prepared usingthe Smix ratios which exhibited higher self-emulsification efficiencyin water. A total of twelve formulations were prepared using theselected Smix ratio (1:1, 1:2, 2:3 for Labrasol:Tween 20, and 2:3 forLabrasol:PEG 600) and Capmul MCM as the oil in the percentagerange of 20–30% (w/w), which could solubilize single dose (8 mg) ofONH. These formulations were subjected to dispersibility test andthermodynamic stability studies to select the stable liquid SNEDDSformulations. The liquid SNEDDS F1, F2, F3, prepared with Smix ratio1:1 for Labrasol, Tween 20 and Capmul MCM passed the thermody-namic stability and dispersibility studies. However, other selectedliquid SNEDDS failed to clear the thermodynamic stability tests.Dispersibility tests showed that dilution of liquid SNEDDS (F1–F3)with water formed slightly bluish colored clear and transparentsolution within a minute. In contrast, other selected liquid SNEDDSdid not produce transparent clear solution on dilution; either it tookmore than a minute or yielded a milky emulsion.

3.4. Characterization of liquid SNEDDS

Dispersibility test showed that all the liquid SNEDDS formu-lations form fine bluish white nanoemulsion in less than 1 min.Table 2 represents the physiochemical properties of the selectedliquid SNEDDS formulations (F1–F3), such as viscocity, refrac-tive index, droplet size and zeta potential. The liquid SNEDDSshowed viscosity in the range of 27 and 38 cps, while the refrac-tive index was in the range of 1.39 and 1.48. Droplet size analysisusing dynamic light scattering was found to range between 118and 250 nm, which indicated that emulsion droplets are in nano-metric range. Zeta potential was found to range between −16.3and −45.8 mV, confirming emulsion droplets as stable and well-separated [29]. The TEM image of the optimized liquid SNEDDSappeared as dark globules with bright surrounding (Fig. 2). In vitrodrug release profile of liquid SNEDDS indicated complete drugrelease within 30 min for all the formulations.

3.5. Optimization and characterization of SSNEGs

The optimized liquid SNEDDS (F1) was selected for the prepa-ration of SSNEGs using different porous carriers. The compositionof different SSNEGs prepared is presented in Table 3. The preparedSSNEGs were evaluated for oil absorption capacity, drug release



Fig. 1. Pseudoternary phase diagram of systems containing 1:1, 1:2, 1:3, 2:3 Smix ratio Labrasol and Tween-20 using Capmul MCM as oil, and water as titrant.

Table 2Characterization of the SNEDDS formulations.

Formulation code Mean viscosity ± SD (cps) Refractive Index ± SD Zeta potential (mV) ± SD Droplet size (nm) ± SDAfter 120 s

F1 27.5 ± 1.01 1.39 ± 0.021 −45.8 ± 0.02 118 ± 0.12F2 32.4 ± 0.99 1.41 ± 0.013 −23.5 ± 0.11 224 ± 0.24F3 38.0 ± 0.91 1.38 ± 0.011 −16.3 ± 0.13 250 ± 0.30

Fig. 2. TEM images of the reconstituted nanoemulsions from (A) the optimized liquid SNEDDS F1 and (b) the optimized SSNEGs G1.

Table 3Formulation composition of SSNEGs.

Component G1 G2 G3 G4 G5

SNEDDS (ml) 0.8 0.8 0.8 0.8 0.8Sylysia 350 (mg) 284 150Sylysia 550 (mg) 488Sylysia 730 (mg) 912Neusilin US2 (mg) 260 100



Fig. 3. Comparative in vitro drug release profile of pure drug, conventional tablet(Zofran® ODT), optimized liquid SNEDDS and SSNEGs formulation containing Sylysia350. Data represented are cumulative %drug release versus time (min) in terms ofmean ± SD (n = 3).

and micromeritic properties. All the batches of SSNEGs showedgood flow characteristics with Carr’s index range between 14 and17%, Hausner’s ratio less than 1.25 and angle of repose (�) < 25.The SSNEGs containing Sylysia 350 and Neusilin US2 (G1 and G5)showed the highest oil absorption tendency due to the highlyporous nature and significant voidage in the particles [39,40]. It hasbeen observed that oil absorption capacity decreased with highergrades of Sylysia. The Sylysia 350 granules (G1) showed the highestoil absorption property due to high porosity and small particle sizecompared to the granules containing Sylysia 550 (G2) and Sylysia730 (G3). The larger particle size of Sylysia shows lower poros-ity leading to lower oil absorption capacity [41]. The in vitro drugrelease studies revealed that all the SSNEGs formulations observedbetter drug release behavior with 50% drug release in 15 min andmore than 80% drug release within 30 min. Among all the for-mulations, the formulation G1 and G5 containing Sylysia 350 andNeusilin US2 granules showed faster dissolution with drug releaseupto 91% in 30 min, ostensibly due to highest oil absorption capacityand faster solubilization in dissolution medium.

3.6. Comparative in vitro drug release studies

The comparative dissolution profiles of optimized SSNEGsformulation (G1) and optimized liquid SNEDDS (F1), marketedpreparation (Zofran® ODT) and pure drug as carried out in SGF(pH 1.2) are presented in Fig. 3. The dissolution profile shows thatthe optimized liquid SNEDDS and SSNEGs exhibited faster drugrelease (98.9% and 99.8% within 15 min) vis-à-vis pure drug andmarketed preparation with maximum drug release in 30 min as41% and 45.7%, respectively. No statistically significant differencewas observed between the drug release by SSNEGs with liquidSNEDDS (p > 0.1). The optimized SSNEGs (DE15 min = 73.6%) and opti-mized liquid SNEDDS (DE15 min = 81.4%) showed better dissolutionperformance vis-à-vis marketed preparation (DE15 min = 34.5%) andpure drug (DE15 min = 28.2%), owing to faster dissolution rate. Like-wise, lower MDT values for optimized SSNEGs (MDT = 4.34 min) andoptimized liquid SNEDDS (MDT = 5.49 min) also indicated higherdissolution rate and faster drug release compared to marketedpreparation (MDT = 2.17 min) and pure drug (MDT = 2.43 min). Thusthe optimized SSNEGs showed a 2–3-fold increase in dissolutionrate vis-à-vis pure drug.

3.7. In vivo pharmacokinetic studies

Fig. 4 depicts the mean plasma concentration profile as a func-tion of time obtained during the in vivo pharmacokinetic studiescarried out in rats on optimized SSNEGs (G1), optimized liquidSNEDDS (F1), marketed preparation (Zofran®) and pure drug. Thenoncompartmental model parameters used to evaluate various

Fig. 4. Plasma concentration–time profile of pure drug, conventional tablet (Zofran®

ODT), optimized liquid SNEDDS and SSNEGs containing 8 mg of ONH after oraladministration in Wistar rats.

pharmacokinetic parameters of ONH absorption, which are sum-marized in Table 4. Linear trapezoidal rule was used to calculatethe area under curve (AUC0→t). Plasma level profiles were signif-icantly increased for SNEDDS and SSNEGs formulations comparedto pure drug and marketed preparation. The Cmax of liquid SNEDDSand SSNEGs was about 3-fold higher than pure drug. The val-ues of AUC0−t of liquid SNEDDS and SSNEGs were 5.4–5.8-foldhigher compared to pure drug, and so were the values of relativebioavailability (%F). Although the AUC of SSNEGs (638.36 ng h/mL)was slightly lower than that of liquid SNEDDS (693.31 ng h/mL),the difference was not found to be statistically significant (p > 0.1)between the two formulations. Similarly, tmax also decreased forSNEDDS (1.73 h) and SSNEGs (1.86 h) compared to the pure drug(2.77 h) and the marketed preparation (1.96 h). The marginallydelayed values of tmax of SSNEGs compared to liquid SNEDDS(1.86 h vs. 1.73 h) are consistent with their difference in disso-lution performance. Similarly, other parameters like MRT0−t andKa are also found to be higher, while t1/2 was lower for SNEDDSand SSNEGs with respect to the pure drug and marketed prepa-ration, indicating enhanced bioavailability. The results of all thepharmacokinetic parameters were found to be highly significant(p < 0.05) for SNEDDS and SSNEGs formulations compared to thepure drug and marketed preparation. No significant differences(p > 0.05), however, was observed in pharmacokinetic parametersbetween SNEDDS and SSNEGs. The above results corroborate thatoral absorption of ONH was significantly improved from SSNEGsand SNEDDS.

3.8. Fourier transformed infrared (FTIR) spectroscopy

The FTIR spectra of drug with various excipients observed nospecific physiochemical interaction. There was no significant dif-ference observed in wave number (cm−1) or functional group ofthe drug in all spectra (Fig. 5).

3.9. Differential scanning calorimetry (DSC)

The DSC thermogram of ONH exhibited a sharp meltingendothermic peak at 185.5 ◦C (Tfus) and with onset at 179.2 ◦C andrecovery at 193.2 ◦C, and total heat consumed was −793.9 J/cal(�H). DSC thermograms of different SSNEGs prepared by physi-cal mixture of SNEDDS with porous carriers showed absence of adefinite melting endothermic peak due to complete solubilizationof the ONH in the vicinity of the lipidic excipients (Fig. 6). This hasalso indicated change in physical nature of the drug in SSNEGs fromthe erstwhile crystalline state to the amorphous one.



Table 4Pharmacokinetic parameters and relative bioavailability of liquid SNEDDS, SSNEGs, marketed tablet (Zofran® ODT) and pure drug administered orally in rats (mean ± SD,n = 6).

Parameters* Pure drug Conventional tablets Liquid SNEDDS SSNEG

tmax (h) 2.77 ± 0.32 1.96 ± 0.43 1.73 ± 0.67 1.86 ± 0.45Cmax (ng/ml) 52.5 ± 5.21 55.7 ± 6.33 91.3 ± 3.15 89.5 ± 2.59AUC0−t (ng.h/ml) 119.5 ± 45.88 118.8 ± 37.21 693.3 ± 51.67 638.3 ± 45.32AUMC0−t (ng.h/ml) 368.9 ± 102.3 379.1 ± 121.6 3602.0 ± 143.7 3179.8 ± 152.4Ka (h−1) 3.04 ± 0.24 4.32 ± 0.62 7.34 ± 0.38 7.56 ± 0.25t1/2 (h) 0.228 ± 0.71 0.160 ± 0.51 0.094 ± 0.63 0.092 ± 0.78MRT0−t (h) 3.091 ± 1.17 3.19 ± 1.44 5.20 ± 1.76 4.98 ± 1.98%F – 99.40 580.06 534.04

* All the parameters were determined with statistical significance set at P < 0.05.

Fig. 5. FTIR spectra of pure drug ONH (A), physical mixture of ONH with CapmulMCM (B), Labrasol (C), and Tween-20 (D), optimized liquid SNEDDS F1 (E), optimizedSSNEGs containing Sylysia 350 (F).

Fig. 6. DSC thermograms of pure drug ONH (A), physical mixture of ONH and Sylysia350 with Capmul MCM (B), Labrasol (C), Tween-20 (D) and optimized SSNEGs G2(E).

Fig. 7. X-ray powder diffractometry of pure drug ONH (A), SSNEGs G1 (B), SSNEGsG2 (C), SSNEGs G3 (D), SSNEGs G4 (E), and SSNEGs G5 (F).

3.10. Powder XRD studies

Fig. 7 depicts the X-ray diffraction patterns of pure drug andSSNEGs. X-ray diffractogram of pure drug showed sharp peaks atdiffraction angle (2�) such as 2◦, 12◦, 12.5◦, 17◦, 18.3◦, 18.8◦, 20.5◦,20.09◦, 23.2◦, 24.3◦, 25.5◦, 27.1◦, 28◦ and 30◦, respectively. However,X-ray diffractogram of SSNEGs showed diffused spectra withoutany characteristic peaks of ONH.

3.11. Accelerated stability studies

During accelerated stability studies, no significant change in SEFtime, droplet size, %DR15 min, and disintegration time was observedupto the period of three months. Drug present in SSNEGs undergoesdegradation by first-order kinetics. The first-order degradation rateconstant ‘K’ was measured from the slope of the lines at each ele-vated temperature (Table 5). From the Arrhenius plot (Fig. 8), Kvalue at 25 ◦C (K25) was determined as 0.00874 days−1, and wasfinally used to calculate the shelf-life of the optimized SSNEGs as3.3 years.



Table 5Degradation rate constant and the shelf-life of optimized SSNEG (G1).

Temperature (◦C) Absolute temperature (K) Slope k log k 1/t × 1000 Shelf-life (t0.9)

25 298.00 0.0004 0.000874 −2.9359 3.3557

3.3 years30 303.00 0.0009 0.002062 −2.8236 3.300340 313.00 0.0011 0.002533 −2.5963 3.194450 323.00 0.0014 0.003224 −2.4015 3.0959

4. Discussions

The important factor considered during formulation of self-nanoemulsifying formulation is to avoid the precipitation of drugin vivo following the dilution in the gut lumen. Therefore, care wasexercised to choose those oils in formulation, which have high solu-bilization capacity for the drug, ensuring complete solubilization ofdrug in the resultant dispersion [42]. During screening of excipientsin the present study, Capmul MCM showed the highest solubility forONH compared to other synthetic oils (Captex 200 and Captex 355)containing medium chain triglycerides (MCTs) and natural lipidscontaining long chain triglycerides (LCTs). Capmul MCM containsa mixture of C8/C10 mono-/diglycerides which favors completesolubilization of drug in the vicinity of triglyceride chains due toshorter chain length. Captex 200/355 (C8/C10 triglycerides), on theother hand, have longer chain length, which is invariably insuf-ficient for complete solubilization of ONH [41,43]. Natural lipidswere not selected due to low solubility of drug in these excipi-ents, stability problems and biocompatibility issues. The lipids withhigher number of medium chain glycerides provide higher surfacearea for drug solubilization due to shorter chain length comparedto long chain triglycerides [38]. Also, the blends of Capmul MCMwith various natural oils were investigated. But none of the com-binations showed solubility more than Capmul MCM itself. Hence,Capmul MCM as lipid, Labrasol® as surfactant, and Tween 20 andPEG 600 as cosurfactants were selected for the construction ofpseudo-ternary phase diagrams. The efficiency of emulsificationwas found to be promising, when the Smix concentration was morethan 65% of SNEDDS formulation. However, emulsification was notefficient with less than 50% of surfactant ratio, because of inade-quate concentration of surfactant causes poor emulsification [44].It was observed that increasing the concentration of the surfac-tant increased the spontaneity of self-emulsification process, butdecreased the extent of emulsification, possibly due to its lipophilicnature (Fig. 1). In a comparative study between two cosurfactants,Tween 20 showed larger self-emulsification region than PEG 600.This may be ascribed to the high HLB value which favors com-plete emulsification and dispersion of oil globules [1]. Thus, theSmix ratios of 1:1 and 2:3 for Labrasol:Tween 20, and of 2:3 forLabrasol:PEG 600 was selected for the preparation of SNEDDS.

The SNEDDS formulations, prepared using selected Smix ratiosand oils, were evaluated using dispersibility test and thermo-dynamic stability studies. It was observed that the SNEDDS

Fig. 8. Arrhenius plot for the optimized SSNEGs (G1).

formulations with Smix ratio of 1:1 for Labrasol and Tween 20passed all the preliminary screening tests. Hence, these werefinally selected for preparing SNEDDS formulations. All the formu-lations were found to be clear and transparent. Refractive indexof the SNEDDS formulation was found to range between 1.39and 1.41, somewhat closer to 1, i.e., refractive index of water,thus confirming quite transparent nature of SNEDDS formula-tion. The viscocity evaluation showed that the prepared liquidSNEDDS exhibited a Newtonian type of flow behavior. The viscocitydecreased with increasing amount of cosurfactant (i.e., Tween 20),ostensibly due to increase in film flexibility caused by hydrophilicnature of the cosurfactant [45,46]. The droplet size and zeta poten-tial measurement revealed that increased in concentration of oilproportionately increased the emulsion droplet size. However,increase in surfactant concentration decreased the droplet size,plausibly owing to increase in net zeta potential [47]. The surfactantforms a thin film at the interface and decreases the globule size andhelps in stabilization of the emulsion. The cosurfactant, on the otherhand, have limited role on droplet size and zeta potential ratheron emulsification property due to its hydrophilic nature [35]. TheTEM image revealed that nanoemulsion appeared as spherical glob-ules after dilution with aqueous phase, attributable to reduction insurface tension due to surfactant and cosurfactant.

The optimized liquid SNEDDS formulation (F1) which, preparedusing a Smix ratio of 1:1 for Labrasol and Tween 20, constitutedONH (1%, w/w), Capmul MCM (20%, w/v), Labrasol (39.5%, w/v) andTween 20 (39.5%, w/v). Complete drug release (99.8%) was observedin 30 min from liquid SNEDDS, whereas pure drug and marketedpreparation showed maximum drug release in 30 min upto 41%and 45.7%, respectively. This indicated that free energy required toform an emulsion was quite low, allowing spontaneous emulsifica-tion of oil droplets at the oil–water interface resulting in immediatesolubilization of drug in dissolution medium [48]. It has also beensuggested that oil, surfactant and cosurfactant swell upon contactwith water due to emulsification of oil droplets in the presenceof surfactant [49]. This reduces the oil droplet size and eventu-ally increases the release rate. Further, increase in concentrationof oil decreased the drug release rate due to inadequate amount ofsurfactant, thus decreasing the emulsification rate.

Among the various SSNEGs prepared from the correspondingSNEDDS using porous carriers, the granules G1 and G5 containingSylysia 350 and Neusilin US2 showed superior oil adsorption ten-dency, good flow and faster drug release characteristics. Further,it was observed that oil adsorption capacity got decreased withhigher grades of Sylysia, i.e., 350, 550 and 730. This may proba-bly be due to increase in average particle size, which decreasedthe total pore volume and porosity [50,51]. In porous carriers, thedrug is adsorbed to certain extent as a thin layer of oil surround-ing the particles. During dissolution, the SSNEGs undergo fasterhydration to produce o/w microemulsions. The high specific surfacearea of these particles contributes towards improved dissolutioncompared to pure drug. The in vitro dissolution studies from vari-ous SSNEGs revealed that drug release from porous carriers weremarginally slower compared to liquid SNEDDS, though the differ-ence was statistically insignificant (p > 0.05). This could be becauseof additional steps involve during dissolution such as disintegra-tion of granules and desorption of liquid SNEDDS from the voids of



porous carriers [31,52]. The SSNEGs when exposed to dissolutionmedium, leads to desorption of the liquid SNEDDS from the silicasurface due to stronger interaction between silica and dissolutionmedium than those between silica and liquid SNEDDS [37]. Drugrelease from SSNEGs was initially slower due to increase in diffu-sion path length for adsorbed liquid formulation in the matrix ofporous carriers [53]. Also, the capillary forces and wicking prop-erties exhibited by the liquid-filled porous carriers, upon contactwith dissolution fluid, could also be responsible for slower drugrelease. Literature reports that drug release from the liquid SNEDDSand SSNEGs tends to follow nearly zero-order kinetics followed bynon-Fickian kinetics, owing to interplay of diffusion and convectionmechanisms [30,54,55].

In comparative drug release study the SNEDDS and SSNEGsshowed quite superior drug release compared to pure drug andmarketed preparation, indicating 2.45-fold increase in extent ofdissolution at 30 min. On the analogous heels, in vivo pharmacoki-netic studies indicated higher Cmax, AUC0−t, AUMC0−t, MRT0−t andshorter tmax for both the liquid SNEDDS and SSNEGs. Enhancedbioavailability of self-nanoemulsifying formulations may be dueto higher solubilization of drug in the gastric milieu and lymphatictransport through intestinal transcellular pathways. The syntheticoil (Capmul MCM) containing MCTs promote lipoprotein synthe-sis and subsequent lymphatic absorption. Further, the surfactantspresent in self-emulsifying formulation helps in bioavailabilityenhancement by augmenting oral absorption through disruptionof intestinal lipid bilayers [41]. On the basis of in vitro dissolutionand in vivo pharmacokinetic studies, it has been confirmed thatself-nanoemulsifying formulations can better enhance the bioavail-ability of ONH. Use of porous carriers in development of SSNEGs canbe a better formulation alternative, as these tend to preserve thephysiochemical and biopharmaceutical integrity of SNEDDS.

No significant change in the characteristic peak of the drug in theFTIR spectra indicated compatibility of drug with excipients. Sim-ilarly, DSC spectra of drug excipient mixture of SNEDDS, SSNEGsexhibited specific change in the fusion temperature of the drugand total heat consumption, due to loss of crystallinity of drugin SNEDDS formulation is known to occur [56]. Transition fromthe crystalline to amorphous state is known to occur in the self-nanoemulsifying formulations, thus augmenting the free energy ofthe molecules in the system, lowering the drug melting point, andeventually improving solubility and dissolution rate [57]. The com-patibility study between the drug-excipient mixtures of SSNEGs asper DSC indicated no possibility of interactions, in agreement withthe results from FTIR spectra. The powder XRD study demonstratedthe crystalline nature of pure drug. In case of the SSNEGs, however,absence of any prominent peak indicated the amorphous nature ofthe drug present in the solubilized state in the proximity of lipidicexcipients [44].

Stability studies ratified that the optimized SSNEGs was robustunder the accelerated temperature and humidity conditions. Highduration of the predicted shelf-life (i.e., 3.3 years) at room tempera-ture, calculated using Arrhenius plot also corroborates the stabilityof the SSNEGs.

5. Conclusions

The present studies successfully embarked upon formulation ofthe SSNEGs of ONH, a highly promising antiemetic drug, and theirsubsequent applications in enhancement of oral bioavailability byimproving its dissolution rate and lymphatic absorption of drug.The pseudo-ternary phase studies successfully lead to the devel-opment of optimized SNEDDS formulations rational blends of lipid(i.e., Capmul MCM), surfactant (i.e., Labrasol) and cosurfactant (i.e.,Tween 20). The porous carriers (Sylysia 350, 550, 730) were found

to be suitable in transforming the SNEDDS into SSNEGs, ostensiblydue to their oil adsorption property. The optimized SSNEGs for-mulation exhibited 3.01-fold augmentation in oral bioavailabilityof ONH in rats as compared to pure drug and marketed prepa-ration. Besides faster drug dissolution in the GI tract, transportthrough lymphatic pathways could be the plausible mechanismplaying stellar role in enhanced drug absorption. The promisingoutcomes of present studies on SSNEGs formulated using porouscarriers can also be extrapolated for successfully augmenting theoral bioavailability of other BCS class II compounds undergoingextensive hepatic first-pass effect.

Conflicts of interest

Authors have no conflicts of interest.

Acknowledgements

The authors are thankful to M/s Aurobindo Pharma, Hyderabad,India, for providing the gift sample of ondansetron hydrochlo-ride. The authors are also thankful to the Institute of Life Sciences,Bhubaneswar, India, for providing the necessary facilities for par-ticle size analysis, and to the Panjab University, Chandigarh, India,for carrying out the powder XRD studies.

References

[1] C.W. Pouton, Eur. J. Pharm. Sci. 29 (2006) 278.[2] S. Beg, S. Swain, M. Rizwan, M. Irfanuddin, D.S. Malini, Curr. Drug. Deliv. 8 (2011)

691.[3] Gattefosse [Online]. http://www.gattefosse.com/en/self-emulsifying-lipid-

formulation/ (accessed on 08.06.12).[4] S. Baboota, S.P. Agarwal, Pharmazie 58 (2003) 73.[5] N. Ahuja, O.P. Katare, B. Singh, Eur. J. Pharm. Biopharm. 65 (2007) 26.[6] Y.S.R Krishnaiah, J. Bioequival. Bioavail. 2 (2010) 28.[7] M.J. Kang, J.Y. Cho, B.H. Shim, D.K. Kim, J. Lee, J. Med. Plants Res. 3 (2009) 1204.[8] R.H. Muller, C. Jacobs, O. Kayser, Adv. Drug Deliv. Rev. 47 (2001) 3.[9] B. Singh, A. Rani, B. Garg, N. Ahuja, R. Kapil, Sci. Pharm. 78 (2010) 303.

[10] V.B. Patravale, A.A. Date, R.M. Kulkarni, J. Pharm. Pharmacol. 56 (2004) 827.[11] O.M. Milhem, C. Myles, N.B. McKeown, D. Attwood, A. D’Emanuele, Int. J. Pharm.

197 (2000) 239.[12] S. Beg, M. Rizwan, A.M. Sheikh, M.S. Hasnain, K. Anwer, K. Kohli, J. Pharm.

Pharmacol. 63 (2011) 141.[13] T. Gershanik, S. Benita, Eur. J. Pharm. Biopharm. 50 (2000) 179.[14] Ondansetron Hydrochloride, Drugs.com [Online]. http://www.drugs.com/

ppa/ondansetron-hydrochloride.html (accessed on 06.06.12).[15] DrugBank, Open data drug and Drug target database [Online].

http://drugbank.ca/drugs/DB00904 (accessed on 07.06.12).[16] S.H. Yang, M.G. Lee, J. Pharm. Pharmacol. 60 (2008) 853.[17] M. Koland, V.P. Sandeep, N.R. Charyulu, J. Young Pharm. 2 (2010) 216.[18] E. Cho, H. Gwak, I. Chun, Int. J. Pharm. 349 (2008) 101.[19] N. Hassan, R.K. Khar, M. Ali, J. Ali, AAPS PharmSciTech 10 (2009) 1085.[20] B. Singh, S. Bandopadhyay, R. Kapil, R. Singh, O.P. Katare, Crit. Rev. Ther. Drug

Carrier Syst. 26 (2009) 427.[21] C.W. Pouton, Adv. Drug Deliv. Rev. 25 (1997) 47.[22] R.N. Gursoy, S. Benita, Biomed. Pharmacother. 58 (2004) 173.[23] B. Singh, L. Khurana, S. Bandyopadhyay, R. Kapil, O.P. Katare, Drug Deliv. 18

(2011) 599.[24] T. Yi, J. Wan, H. Xu, X. Yang, Eur. J. Pharm. Biopharm. 70 (2008) 439.[25] S. Faucher, R. Carlini, J. Chung, US2010/0316946; 2010.[26] S. Booth, A. Clarke, J. Newton, US6630150 (2001).[27] S. Nazzal, M.A. Khan, AAPS PharmSciTech 3 (2002) E3.[28] B.G. Tang, G. Cheng, J.-C. Gu, C.-H. Xu, Drug Discov. Today 13 (2008) 606.[29] R.P. Dixit, M.S. Nagarsenker, Eur. J. Pharm. Sci. 35 (2008) 183.[30] P. Patil, P. Joshi, A. Paradkar, AAPS PharmSciTech 5 (2004) e42.[31] M.J. Kang, S.Y. Jung, W.H. Song, J.S. Park, S.U. Choi, K.T. Oh, H.K. Choi, Y.W. Choi,

J. Lee, B.J. Lee, S.C. Chi, Drug Dev. Ind. Pharm. 37 (2011) 1298.[32] H. Takeuchi, S. Nagira, H. Yamamoto, Y. Kawashima, Int. J. Pharm. 293 (2005)

155.[33] T. Uchino, N. Yasuno, Y. Yanagihara, H. Suzuki, Pharmazie 62 (2007) 599.[34] Dissolution methods database [Online]. http://www.accessdata.fda.gov/

scripts/cder/dissolution/dsp SearchResults Dissolutions.cfm (accessed on31.05.12).

[35] M.N. Gosh, Fundamentals of Experimental Pharmacology, vol. 39, Hilton andCompany Publishers, Kolkata, 2007.

[36] E.J. Freireich, E.A. Gehan, D.P. Rall, L.H. Schmidt, H.E. Skipper, Cancer Chemother.Rep. 50 (1996) 219.

[37] J. Liu, J.T. Stewart, J. Chromatogr. B: Biomed. Sci. Appl. 694 (1997) 179.



[38] T.R. Kommuru, B. Gurley, M.A. Khan, I.K. Reddy, Int. J. Pharm. 212 (2001) 233.[39] Fuji Sylysia, Sylysia FCP, Fuji Chemical Industries [Online]. http://www.

tcrindustries.com/Principals/BROCHURES/fujibrochures/FCP%20Brochure.pdf(accessed on 05.06.12).

[40] Neusilin [Online]. http://www.neusilin.com/ (accessed on 08.06.12).[41] C.J.H Porter, N.L. Trevaskis, W.N. Charman, Nat. Rev. Drug Discov. 6 (2007) 231.[42] S. Chakraborty, D. Shukla, B. Mishra, S. Singh, Eur. J. Pharm. Biopharm. 73 (2009)

1.[43] S. Bandyopadhyay, O.P. Katare, B. Singh, Colloids Surf. B Biointerfaces, in press,

doi.org/10.1016/j.bbr.2011.03.031.[44] A.R. Dixit, S.J. Rajput, S.G. Patel, AAPS PharmSciTech 11 (2010) 314.[45] N. Parmar, N. Singla, S. Amin, K. Kohli, Colloids Surf. B Biointerfaces 86 (2011)

327.[46] S.V. Biradar, R.S. Dhumal, A. Paradkar, J. Pharm. Pharm. Sci. 12 (2009) 17.[47] M. Rizwan, M. Aqil, A. Azeem, S. Talegaonkar, Y. Sultana, A. Ali, J. Exp. Nanosci.

5 (2010) 390.

[48] K. Kohli, S. Chopra, D. Dhar, S. Arora, R.K. Khar, Drug Discov. Today 15 (2010)958.

[49] B.J. Lee, D.H. On, J.O. Kim, M.J. Hong, J.P. Jee, J.A. Kim, B.K. You, J.S. Wo, C.S. Yong,H.G. Choi, Eur. J. Pharm. Biopharm. 72 (2009) 539.

[50] L. Wang, F.D. Cui, H. Sunada, Chem. Pharm. Bull. 54 (2006) 37.[51] Y. Ito, H. Arai, K. Uchino, K. Iwasaki, N. Shibata, K. Takada, Int. J. Pharm. 289

(2005) 69.[52] G. Ahuja, K. Pathak, Ind. J. Pharm. Sci. 71 (2009) 599.[53] P. Patil, A. Paradkar, AAPS PharmSciTech 7 (2006) E28.[54] C. Sander, P. Holm, AAPS PharmSciTech 10 (2009) 1388.[55] SYLYSIA FC, Fuji Sylysia [Online]. http://www.tcrindustries.com/Principals/

BROCHURES/fujibrochures/FCP%20Brochure.pdf (accessed on 08.06.12).[56] S. Bhatt, P. Trivedi, J. Chem. Pharm. Res. 3 (2011) 472.[57] E.I. Taha, Sci. Pharm. 77 (2009) 443.

Ondanstetron SNEGs

Documents

drug release studies

optimized liquid snedds

dilution of liquid snedds

surfaces b

preformulation studies

pure drug

indiaa r t i c

optimized ssnegs over80