1. INTRODUCTION:

Primary challenge of any oral formulation design program is to maintain drug solubility within G.I tract and particularly maximizing drug solubility within primary absorption site of the gut. The effective use of lipid based drug delivery systems have gained much importance as they utilize well known food effects of ingested lipids. [1] For lipophilic drug compounds which exhibit dissolution rate limited absorption self microemulsifying drug delivery systems (SMEDDS) can offer great improvement in rate and extent of absorption, leading to reproducible blood time profiles of BCS class II drugs in particular.[2,3]

According to Lipinski’s rule of five for oral absorption trends, it predicts that poor permeation or poor absorption is more likely when there are more than 5-H bond donars, more than 10 H-bond acceptors, with molecular weight >500 and log P>5.

Such drug candidates based on BCS classification system are suitable for formulation as SMEDDS. These are formulations forming transparent microemulsions with oil droplets ranging between 50-200nm. consists primarily of oil and surfactant mixtures, the performance of SMEDDS system is dependent on polarity of oil droplets which is governed by HLB of surfactants. Hence ideal SMEDDS systems are formulated with optimum concentrations of lipids and surfactant mixtures. [4]

Repaglinide which is a carboxymethyl benzoic acid derivative and meglitinide class drug that lowers the blood glucose [5].It was basically developed to control meal related glucose fluctuation in type 2 diabetes mellitus patients on stimulating the release of insulin secretion from pancreas. This is directly related to effective functioning of β-cell exhaustion [6]. Repaglinide is BCS class II drug with low aqueous solubility which also has been formulated as solid dispersion, complexed with HP β CD inclusion complexes and as coamorphous saccharin complexes to improve its oral absorption. This is a first attempt to formulate the drug as self emulsifying drug delivery systems to improve the aqueous solubility of the drug [7].

2. MATERIALS AND METHODS:

2.1. Materials:

Repaglinide was a gift sample from Dr.Reddy’s laboratories, Hyderabad. Labrasol and Transcutol were kindly donated by Gattefosse Corp, France; Neusilin was donated by Fuji Chemicals, Japan. Sesame oil and polyethylene glycol 400 (PEG400) were purchased from S.D fine chemicals ltd, Mumbai.

2.2. Methodology:

1.2.1 Solubility studies:

Solubility is an important parameter in determining the excipients for the formulation of SMEDDS. These studies were conducted by taking excess amount of drug dissolved in the vehicles consisting of oils, surfactants and co-surfactants. The drug vehicle mixtures were shaken for 48 hrs, later equilibrated for 24 hrs. [8]. The samples were subjected to centrifugation at 3000 rpm for 15 min, the supernatant was suitably diluted and the drug concentration in each vehicle was quantified by UV-spectrophotometer.

1.2.2 Screening of the surfactants:

The surfactants were further screened based on their ability to emulsify the selected oil phase. To determine the emulsification ability, 20 µl of surfactant was added to 20 µl of selected oily phase, mixed thoroughly and then 25 µl of this mixture was diluted 25 ml with distilled water. The ease of formation of emulsions was then monitored by the number inversions of volumetric flask required to produce a uniform emulsion. The emulsions were allowed to stand for 2 h and later their transmittance was measured at 638.2nm using UV-vis spectrophotometer against distilled water as blank.

1.2.3 Screening of the co-surfactants:

Co-surfactants were screened based on their efficacy to improve the micro emulsification ability of the selected surfactants. For this 40 µl of surfactant was added to 20 µl of selected co-surfactant. The selected oil phase 60 µl was added to the above mixture and mixed thoroughly with gentle heating on a water bath and then 25 µl of this mixture was diluted 25 ml with distilled water. The ease of formation of emulsions was monitored by the number of inversions of volumetric flask required to produce a uniform emulsion. [9] The emulsions were allowed to stand for 2 h and later their transmittance was measured at 638.2nm using UV-Vis spectrophotometer against distilled water as blank.

1.2.4 Construction of the pseudo ternary phase diagrams:

Pseudo ternary phase diagrams are done to select the microemulsifying region for proper formulation involving the oils, surfactants and co-surfactants. Water titration method was employed and the oil to s/cos ratios were taken in the order 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9. The s/cos ratios were varied as 1:1, 1:2, 1:3, 1:4, 2:1, 3:1, 4:1. The oil and surfactant mixtures were titrated with water till end point of transparency from turbidity [10] Thus the phase diagrams were constructed using chemix school software and the microemulsion existing boundaries were identified.

2.3 Formulation of Repaglinide SMEDDS:

The formulations were prepared by initially dissolving co surfactant (transcutol/PEG 400) and surfactant (Labrasol) at 60◦C in an isothermal water bath, then drug is dissolved in the s/cos mixture. Oil (sesame oil ) was then added and mixture was cooled to ambient temperature, then the final mixture was sonicated to get a clear solution. The formulation is equilibrated at ambient temperature for 48 hours and examined for signs of turbidity (or) phase separation. The liquid SMEDDS were solidified by adsorbing them onto Neusilin which serves as carrier [11]. In all the formulations, the drug concentration was constant as 1 mg/mL of liquid SMEDDS with sesame oil as oil phase and Labrasol as surfactant , whereas for formulations RF1 to RF15 S/COS ratio was 1:1 and transcutol was used as co-surfactant, RF16 to RF30 it was maintained as 3:1 with PEG 400 as co-surfactant.(Table 1).

2.4 Evaluation of formulated SMEDDS:

2.4.1. Visual observation, phase separation of emulsion:

Formulation of SMEDDS containing the drug was diluted with 200 mL of distilled water (37◦C) for checking visual appearance, the diluted preparation was vortexed for one minute then the mixtures was stored for a period of 24 hrs, and phase separation and precipitation were observed visually. Mixtures exhibiting very negligible phase separation were used for subsequent studies. The prepared SMEDDS on dilution with distilled water in ratio of 1:100 were investigated for phase separation, graded from A to E according to visibility grading system. Formulations that exhibited no phase separation, precipitation and formed rapidly with a visibility grade A, were evaluated further [12].

2.4.2. Determination of self-emulsification time and optical clarity:

The efficiency of self-microemulsification was estimated by stirring SMEDDS at 100 rpm using water and 0.1 N HCl solution as medium at 37 ± 0.5◦C. SMEDDS formulation was added to the medium and the contents mixed gently at 100 rpm and the time required to form micro emulsion on dilution of SMEDDS with water was determined [13]. Each formulation (1 mL) was diluted with 100 mL of distilled water after SMEDDS formation and % transmittance was measured at 630nm using distilled water as blank to determine optical clarity.

2.4.3. Robustness to dilution:

The robustness to dilution of SMEDDS was studied by diluting the formulation to 50,100 and 1000 times with 0.1N Hcl and 6.8 phosphate buffer. The diluted samples were stored for 24 hrs and then observed for any phase separation or precipitation.

2.4.4. In vitro dissolution studies:

The drug release from the SMEDDS formulations was determined by employing USP dissolution type II apparatus.900 mL of pH 6.8 buffer was taken in the dissolution vessel and solid SMEDDS formulation was filled in hard gelatin capsule was dropped in the dissolution medium, agitated at 50 rpm at 37◦C. At pre-determined time intervals of 5, 10, 15, 30, 40, 50, 60 minutes, 5 mL of the sampling was done and the drug concentration was determined by using UV spectrophotometer at wavelength 243nm. The amount of Repaglinide released from SMEDDS formulation was determined in pH 6.8 phosphate buffer for all the formulations and in SGF(pepsin media) for the optimized formulation for a period of one hour [14].

Simulated gastric fluid (SGF): Prepared by dissolving 2g sodium chloride, 3.2g pepsin in 7ml distilled water. Finally volume is made up to 100ml with distilled water and pH adjusted to 1.2.

2.4.5. Drug excipient compatibility studies:

FTIR spectrums of drug and solid drug-microemulsion formulation were done by means of a FTIR spectrophotometer (Bruker-Alpha T) [15]. The samples in the potassium bromide disks were scanned with a resolution of 4 cm⁻¹over in the range of 400–4000 cm⁻¹.

2.4.6. Scanning electron microscopy (SEM) of SMEDDS One gram of the optimized SMEDDS was randomly sampled from hard gelatin capsules. The formulations were mounted on stub. This specimen was coated with gold particles and observed with a LV-SEM 5800 (JEOL, Japan) at accelerating voltage of 10kV. SEM micrographs of the surfaces and cross-sections of SMEDDS were photographed [16].

2.4.7. Transmission electron microscopy (TEM) studies of SMEDDS:

Microemulsion droplets produced by the dilution of optimized SMEDDS with distilled water were visualized using a JOEL 2100F Electron microscope, with accelerating voltage of 100kV. Samples were negatively stained with 1% aqueous solution of phosphor tunsgstic acid and visualized under the microscope at 100 k fold enlargement [17].

2.4.8. Droplet size analysis and zeta potential:

The droplet size of the SMEDDS formulations were measured after diluting the samples in distilled water, by using Malvern zeta sizer. The parameters like size, polydispersity index and zeta potential were estimated [18].

2.4.9. Cloud point measurement:

The formulation was diluted with 50 mL of water in a beaker and placed on water bath while gradually increasing the temperature till the diluted formulation turns cloudy. This study gives the information about the stability of the microemulsion at body temperature. Emulsions containing non-ionic surfactants tends to turn cloudy above certain temperature hence cloud point is measured which clearly determines the temperature above which the clear emulsion becomes cloudy.

3. RESULTS

3.1. Solubility studies:

The solubility studies data has shown Repaglinide being having good solubility in Sesame oil, Labrasol as surfactant, transcutol and PEG 400 as co-surfactants as shown in table 1. Thus these excipients were selected for the formulation of SMEDDS. Solubility studies being the preliminary studies for screening of the excipients were conducted to identify the suitable excipients for the final formulation.

Table 1: Solubility of Repaglinide in various vehicles

Vehicles	Solubility (mg/ml)
Span 80	02.06±0.52
Span 20	3.33±0.54
Tween 20	11.23±0.11
Tween 80	14.34±1.51
Labrasol	50.89±0.10
Transcutol	64.56±1.44
PEG 400	57.09±0.87
PEG 300	4.12±0.41
Oleic acid	2.23±0.53
Sunflower oil	12.34±1.63
Cotton seed oil	8.34±1.12
Miglyol	6.21±0.49
Cremophor EL	5.34±0.42
Water	0.12±0.04
Brij 35	6.56±1.54
Cremophor RH 40	3.65±0.87
Sefsol 812N	5.45±0.67
Acrysol EL 135	3.67±1.02
Acrysol K 140	5.67±1.34
Sesame oil	35.7±0.45
Propylene glycol	8.8±0.56
Iso propyl myristate	2.1±1.76
Glycerol	3.5±0.89
Lauroglycol 90	2.3±1.38
Labrafac PG	4.3±1.36

Data is given as mean ±SD(n=3)

3.1.1. Screening of the surfactants:

Surfactants are an important part of lipid systems as they form efficient emulsifying atmosphere for the drug with the oils used. According to the studies conducted to select proper surfactant as seen in table 2, the good transmittance values for Labrasol with sesame oil has made us to select it as the non-ionic surfactant for the SMEDDS formulations.

3.1.2. Screening for the co-surfactants:

The correct value of HLB of the surfactants are important for good lipid systems, however selection of the better co-surfactant for Repaglinide SMEDDS has been done based on the % transmittance of oil and s/cos mixture as seen in table III. Both transcutol and PEG 400 have given transparent emulsions as observed in % transmittance values.

3.2. Formulation of Repaglinide SMEDDS.

The SMEDDS of Repaglinide were planned according to the preliminary studies discussed above and the formulations were done as seen in table 4. Proper selection of all the excipients is a key factor in designing SMEDDS formulations hence all the formulations were formulated based on the optimum concentrations of oil, surfactant and co-surfactant.

Table 4: Formulation of Repaglinide SMEDDS:

Formulation	% of Sesame oil	S/COS ratio	% of labrasol	% of transcutol
RF1	11.4	1:1	44.3	44.3
RF2	14.7	1:1	42.65	42.65
RF3	16.6	1:1	41.7	41.7
RF4	18.4	1:1	40.8	40.8
RF5	21.2	1:1	39.4	39.4
RF6	23.2	1:1	38.4	38.4
RF7	25.4	1:1	37.3	37.3
RF8	28.6	1:1	35.7	35.7
RF9	30.4	1:1	34.8	34.8
RF10	31.8	1:1	34.1	34.1
RF11	32.8	1:1	33.6	33.6
RF12	33.6	1:1	33.2	33.2
RF13	34.4	1:1	32.8	32.8
RF14	35.4	1:1	32.3	32.3
RF15	36.4	1:1	31.8	31.8
Formulation	% of Sesame oil	S/COS ratio	% of labrasol	% of PEG 400
RF16	10.1	3:1	67.4	22.4
RF17	12.4	3:1	65.7	21.9
RF18	14.2	3:1	64.3	21.4
RF19	16.6	3:1	62.5	20.8
RF20	18.2	3:1	61.5	20.4
RF21	20.2	3:1	59.8	19.9
RF22	22.2	3:1	58.3	19.4
RF23	24.4	3:1	56.7	18.9
RF24	26.2	3:1	55.3	18.4
RF25	28.4	3:1	53.7	17.9
RF26	30.2	3:1	52.3	17.4
RF27	32.4	3:1	50.7	16.9
RF28	34.9	3:1	48.8	16.2
RF29	36.6	3:1	47.5	15.8
RF30	38.6	3:1	46	15.3

3.3. Evaluation of formulated SMEDDS:

3.3.1. Physicochemical evaluation:.

The primary evaluation test being checking the dispersibility , phase separation and visibility grade. The test was done on diluting the SMEDDS formulations with distilled water, the formulations with good dispersibility of grade A with no phase separation and precipitation as shown in table 5 were selected for further evaluation tests. 20 formulations of Repaglinide were selected for further evaluation of self emulsification test in 0.1N Hcl and pH 6.8 phosphate buffer. The reason for the remaining formulations not passing the test could be improper selection of excipient concentration from the phase diagrams.

The emulsification test results have shown the emulsification times in the range of 56 to 340 seconds the times being highly influenced by the amount of oil phase. SMEDDS having less emulsification time had good tendency for emulsification and those which took more time to emulsify had satisfactory nature. However the emulsification time did not alter much with the pH. Based on the results of emulsification test better formulations were selected 18 formulations of Repaglinide were further evaluated for optical clarity in which % transmittance of the SMEDDS is measured till 24hrs after preparation to test the stability of formulation to precipitation. Cloud point was measured to find out the temperature at which the emulsion is turning cloudy to test the stability of emulsions at body temperature and drug content was also estimated. There was no difference in % transmittance values after 24hrs storage,with all the formulations having a cloud point above 80⁰C and drug content of 98-99%. These values have suggested good stability of prepared formulations. The FTIR spectra of Repaglinide is characterized by sharp bands at 3308cm^-1 due to N-H stretching, 2934 cm^-1indicates presence of CH stetching, 1686 cm^-1 can be attributed to C=O stretching, 1635 cm^-1 due to C=C stretching and deformation due to CH can be seen in the molecule as absorption band at 1567cm^-1.The FTIR spectra of Repaglinide SMEDDS can be characterized with 3421cm^-1 due to N-H stretching, 2925 cm^-1indicates presence of CH stetching, 1700 cm^-1 can be attributed to C=O stretching, 1637 cm^-1 due to C=C stretching and deformation due to CH can be seen in the molecule as absorption band at 1458 cm^-1 as seen in fig 2 and 3.The presence of absorption bands in the formulation is similar to that of the drug, without any shifts it can be confirmed that there is no interaction of the drug with the excipients used.

FIG 2: FTIR of Repaglinide

FIG 3: FTIR of Repaglinide SMEDDS

3.3.2. In –vitro drug release studies:

The SMEDDS formulation of Repaglinide RF1 to RF15 consisting of labrasol as surfactant and transcutol as co-surfactant in the ratio of 1:1, with sesame oil as oil phase were seen to possess drug release on accordance to the amount of oil phase used, RF1 , RF2 and RF3 were seen to release 85, 87 and 88 percentage due to less oil phase , RF15 and RF15 were seen to release 87 and 88 percentage due to more oil component, the optimized formulation was RF7 releasing 97 percentage of Repaglinide in 30 minutes. RF8 was seen to release 96 percentage at the end of 60 minutes, the other formulations RF4, RF5, RF6, RF9, RF13 were seen to release 90-92 percent at the end of 60 minutes as seen in fig 4.

The Repaglinide formulations RF16 to RF20 consisted of labrasol as surfactant and PEG 400 as co-surfactant in the ratio of 3:1 also were evaluated for the drug release studies as they were seen to pass the other physicochemical tests with good results, the oil phase was sesame oil, RF16, RF17, RF19 and RF20 were seen to release 90-95 percent of drug at the end of 60 minutes, RF18 was observed to release 96percent of drug in 45 minutes, this is due to the optimum ratio and compositions of the components used. The marketed tablet of Repaglinide (prandin) was seen to release 60 percent of drug at the end of 60 minutes , the pure drug has shown only 32 percent in the same duration, the SMEDDS formulations of repaglinide RF7 and RF18 had good drug release in less time as discussed , this is attributed to good compositions of the three components used in the formulations which were selected from the phase diagram showing large microemulsion area, this improvement in the solubility of the otherwise poorly soluble drugs is due to the spontaneous formation of microemulsions In –vivo which has lead to decrease in the particle size owing to increase in the surface area leaving the drug as fine dispersed particles in the G.I fluids [21].

The percentage drug release values of the optimized formulations did not show much difference when dissolution was performed in phosphate buffer and SGF (pepsin media) hence it can be said that the SMEDDS formulations were stable in pepsin media.

Table 5: Dispersibility , phase separation and visibility grade of Repaglinide SMEDDS.

Formulation	Dispersibility	Phase separation	Precipitation
RF1	A	X	XX
RF2	A	X	XX
RF3	A	X	XX
RF4	A	X	XX
RF5	A	X	XX
RF6	A	X	XX
RF7	A	X	XX
RF8	A	X	XX
RF9	A	X	XX
RF10	B	X	++
RF11	B	X	++
RF12	B	X	++
RF13	B	X	XX
RF14	B	X	XX
RF15	B	X	XX
RF16	A	X	XX
RF17	A	X	XX
RF18	A	X	XX
RF19	A	X	XX
RF20	A	X	XX
RF21	A	X	XX
RF22	D	+	++
RF23	D	+	++
RF24	D	X	++
RF25	C	X	++
RF26	D	X	++
RF27	C	X	++
RF28	D	X	++
RF29	D	+	++
RF30	D	+	++

X- nophase separation, XX- no precipitation,+- phase separation, ++- precipitation.

Fig 4: Cumulative percent drug released from Repaglinide SMEDDS

3.3.3. Droplet size analysis and zeta potential:

The SMEDDS formulations which have shown good drug release were selected for droplet size analysis, polydispersity index and zeta potential studies. The reconstituted SMEDDS have shown droplet sizes below 200nm as described by the classical definition of microemulsion [22]. Repaglinide formulations RF7 and RF18 were seen to possess droplet size of 11.07nm and 55.12nm as observed in table 6. The droplets were seen to have a narrow and homogeneous size distribution with PDI (polydispersity index) below 0.3. PDI (<0.1) indicates a homogenous dispersion, while a PDI (>0.3) indicates a higher heterogeneous dispersion. The optimized SMEDDS formulations, RF7, RF18 were seen to have a zeta potential values of -4.23 and -15.2 respectively.

The negative charge on the droplets is due to the presence of free fatty acids. In general, the zeta potential value of ±30mV is sufficient for the stability of the system. All the formulations have zeta potential values within the range and the presence of negative charge on the droplets will prevent the aggregation and make the system more stable in the G.I environment.

Table 6: Droplet size analysis and Zeta potential of Repaglinide SMEDDS

Formulations	Droplet size(nm)	Poly dispersity index	Zeta potential (mV)
RF6	68.68	0.268	-2.91
RF7	21.07	0.131	-4.23
RF8	147.1	0.234	-2.14
RF9	186.6	0.277	-2.50
RF17	126.2	0.189	-3.15
RF18	55.12	0.240	-5.12
RF19	138.2	0.214	-11.2
RF20	161.5	0.231	-15.2

3.3.5. SEM and TEM analysis of the formulation:

The solid SMEDDS powder was subjected to scanning electron microscopy and the surface of the powders is seen to be smooth with no visible oil droplets, which is an indication of efficient adsorption onto solid carrier as seen in fig 5. TEM micrographs revealed that the microemulsions were spherical in shape with size in the range of 100nm with drug dispersed in hydrophobic core consisting of oil and surfactant. The droplets were seen to be well dispersed with no aggregation or cluster formation, spherical in shape uniform and homogeneous as seen in fig 6.

Fig 5:SEM micrograph of Solid SMEDDS of Repaglinide

Fig 6: TEM image of Liquid Repaglinide SMEDDS

4. CONCLUSION :

The present research was focused on development of novel SMEDDS formulation of poorly soluble antidiabetic drug Repaglinide. The solubility studies and surfactant co-surfactant screening studies have led to selection of excipients for constructing pseudoternary phase diagrams for selection of optimal concentration of the various excipients used in the formulation. The prepared formulations have been subjected to various physicochemical evaluations and the main objective of the research which is improving the solubility and bioavailability of the drug was achieved as seen in droplet size analysis of the formulations where the particle size has been observed to be below 100nm. The in-vitro release studies have further supported the cause and ex-vivo studies have clearly depicted the efficiency of the SMEDDS formulation in improving the permeability aspect too. Thus the focused aspect of the study remains successful with a novel formulation of Repaglinide being developed and proved to be stable on long storage , this formulation can therefore be tested for in-vivo bioavailability studies too in support of the reported data for further industrial applications.

5. REFERENCES:

[1] Johanna Mercke Odeberg, Peter Kaufmann, Karl-Gunnar Kroon et al . Lipid drug delivery and rational formulation design for lipophilic drugs with low oral bioavailability, applied to cyclosporine.Int.J.Pharm. 20;2003:375-382.

[2] Kang. BK, Lee JS, Chon SK, et al. Development of self microemulsifying drug delivery systems (SMEDDS) for oral bioavailability enhancement of simvastatin in beagle dogs. Int J Pharm.274; 2004:65-73.

[3] Sandeep Kalepu, Mohanvarma Manthina, Veerabhadraswamy Padavala. Oral lipid –based drug delivery systems – an overview. Acta Parmaceutica Sinica B. 3(6);2013:361-372.

[4] Date AA, Nagersenkar MS. “Design and evaluation of self nanoemulsifying drug delivery system(SNEDDS) for cefpodo ximeproxetil”. Int. J. Pharm. 329;2007:166-172.

[5] V. Vijayan, K. Ravindra Reddy, S. Sakthivel et al. Optimization and characterization of repaglinide biodegradable polymeric nanoparticles loaded transdermal patches: In vitro and in vivo studies. Colloids and Surfaces B: Biointerfaces .111;2013:150-155.

[6] Culy C.R, Jarvis B. Repaglinide : a review of its therapeutic use in type 2 diabetes mellitus. Drugs. 61; 2001:1625-1660.

[7] Yuan Gao, Jiao Xiao, Xuan Qi, et al. Coamorphous repaglinide-saccharin with enhanced dissolution. Int. J. Pharm. 450;2013:290-295.

[8] Cathelleya Mekjaruskul, Yu-Tsai Yang, Marina G.D. Leed, et al. Novel formulation strategies for enhancing oral delivery of methoxyflavones in Kaempferia parviflora by SMEDDS for complexation with 2-hydroxypropyl-β-cyclodextrin. Int. J. Pharm. 445; 2013:1-11.

[9] Venkataramana K, Suresh B, Raju J, Prabhakar RV. Oral self-emulsifying powder of lecardipine Hcl. Powder Technol .221; 2012:375–385.

[10] Mette Grove, Anette Mullertz, Jeanet Logsted Nielsen,et al. Bioavailability of seocalcitol II: Development and characterization of self-microemulsifying drug delivery systems (SMEDDS) for oral administration containing medium and long chain triglycerides. Eur J Pharm Sci. 28;2006:233-242.

[11] Elinor Josef, Havazelet Bianco-Peled. Sponges carrying self-microemulsifying drug delivery systems. Int. J. Pharm .458(1); 2013:208-217.

[12] Khoo SM, Humberstone AJ, Porter CJH et al. Formulation design and bioavailability assessment of lipidic self-emulsifying formulations of halofantrine. Int J Pharm. 167; 1998:155–64.

[13] Shweta Gupta, Sandip Chavhan, Kruthika K Sawanth. Self-nanoemusifying drug delivery systems for adefovir-dipivoxil: Design, characterization, in vitro and ex vivo evaluation. Colloids and Surfaces A: Physiochem Eng Aspects. 392; 2011:145-155.

[14] L. Wang, J. Dong. Design and optimization of a new self – nanoemulsifying drug delivery system. J Colloid Interface Sci. 330; 2009:443-448.

[15] Rahul S, Kalhapure, Krishnacharya G, Akamanchi. Oleic acid based heterolipid synthesis, characterization and application in self-microemulsifying drug delivery system. Int.J.Pharm.425; 2012:9-18.

[16] Yogeshwar G.Bacchav, Vandana B.Patravale. SMEDDS of glyburide: Formulation, In vitro evaluation and stability studies. AAPS Pharm Sci Tech .10(2); 2009:482-487.

[17] Pradeep R. Patil, S. Pravan, R.H Shobha Rani, et al. Bioavailability assessment of ketoprofen incorporated in gelled selfemulsifying formulation: A technical note. AAPS Pharm Sci Tech.6 (1); 2005:E9-E13.

[18] S.E. Eltayeb, Zhiguisu, Yongping Shi et al. Preparation and optimization of transferin modified artemether lipid nanospheres based on orthogonal design of emulsion formulation and physically electrostatic adsorption. Int. J. Pharm .452; 2013:321-332.

[19] Hu YQ, Zheng LY, Qianc Q, Yu WH. Absorption of phenol red from rat intestine. J Chin Pharm Univ. 27; 1996:355–9.

[20] Sushant Patil, Shital Suryavanshi, Sulabha Pathak et al. Evaluation of novel lipid based formulation of β-Artemether and Lumefantrine in murine malaria model. Int. J. Pharm. 455; 2013:229-234.

[21] K. Itoh, Y. Tozuka, T. Oguchi, K. Yamamoto. Improvement of physicochemical properties of N-4472 part I formulation design by using self-microemulsifying system. Int. J. Pharm. 238; 2002:153-160.

[22] Minghui Sun, Xuezhen Zhai, Kewen Xue et al. Intestinal absorption and intestinal lymphatic transport of sirolimus from self-microemulsifying drug delivery systems assessed using the single pass intestinal perfusion (SPIP) technique and a chylomicron flow blocking approach: Linear correlation with oral bioavailabilities in rats. Eur.j.Pharm.Sci.43; 2011:132-140.

[23] A. Zvonar, K. Bolko, M. Gasperlin. Microencapsulation of self-micremulsifying systems: Optimization of shell-formation and hardening process. Int.J.Pharm.437; 2012:294-302.

Received on 22.07.2014 Modified on 05.08.2014

Research J. Pharm. and Tech. 7(11): Nov. 2014 Page 1246-1252

Surfactant	Span 80	Tween 20	Tween 80	Labrasol	Cremophor EL	CremophorRH40	Span20	Lauroglycol 90
% Transmittance	55.7±0.57	73.6±1.56	88.5±1.45	98.6±0.42	77.6±0.12	65.76±0.34	56.7±1.56	50.45±3.56

Surfactant	Transcutol	PEG 400	PEG 300	Brij 35	Propylene glycol	Glycerol
% transmittance	98.7±3.18	96.7±1.14	93.6±3.15	76.8±1.15	86.5±0.34	54.5±1.06