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Effect of Surfactants and Cholesterol on Physical Properties Ofbcs Class Ii Drug Loaded Niosomes


SHALIN C*1, SWATHI P NAIR1, SHIJILA P1


1. Department of Pharmaceutics, Rajiv Gandhi Institute of Pharmacy Trikaripur, Kasargod, Kerala, 671310


ABSTRACT

Niosomal promising drug delivery system and have successfully used in various treatment in the medical field. It shows sustained drug release and the localized or targeted drug delivery. Both hydrophilic and lipophilic drugs are incorporated into niosomes to improve its efficacy. So many factors will affect the physical characteristics of niosomal vesicle. The physicochemical characters of encapsulated drug, type and properties of non-ionic surfactant and the cholesterol content may affect the properties of niosomes. Loratadine is an antihistaminic drug used for the treatment of allergic diseases. It belongs to BCS class II. Effect of surfactant and cholesterol on the loratadine loaded niosomesbe investigated by preparing niosomes using Lipid Film Hydration method. Niosomes were assessed for particle size was determination, morphological studies, entrapment efficiency and in-vitro drug release. The mean particle size was found to be in between 3.49-7.48µm. The niosomes prepared by using span 60 shows highest entrapment efficiency 94.9% and in-vitro drug release 92.61800.90.

Keywords: -Niosome; Cholesterol; Non-ionic surfactant; BCS II;

INTRODUCTION 

Niosomes are radically non-ionic surfactant based vesicle in which an aqueous solution of solute is entirely enclosed by a membrane resulted from the self-assembly of hydrated surfactant molecules as bi-layer.12Niosomes are one of the best drug delivery system among these carriers. Structurally, niosomes are similar to liposomes and also are equiactive in drug delivery potential but high chemical stability and economy make niosomes superior to liposomes.1

The formation of vesicle size was regulated by different types of physicochemical factors such as HLB value of surfactants, Nature of drug, Concentration of cholesterol and non-ionic surfactant etc.2Niosomes are amphiphilic in nature.13The hydrophilic drug will entrap within the aqueous cavity and lipophilic drug will entrap between the non-ionic surfactant bi-layer. 

The vesicle formations are regulated by several factors like HLB value of non-ionic surfactants, nature of drug, concentration of cholesterol and non-ionic surfactant surfactants, method of preparation, etc.14 The variation in vesicle formation will alter the drug release, entrapment efficiency, stability, etc of the niosomes which can be studied by preparing niosomes using different non-ionic surfactants and cholesterol with varying ratios.4Loratadine belongs to the BCS class II and this drug shows high lipophilic characters. It will entrap between the non-ionic surfactant bi-layer5. The effect of surfactants and cholesterol on the drug loaded niosomes can be studied using this drug.

MATERIALS AND METHODS

Loratadine was a kind gift sample from Caplin.laboratories.Ltd, Tamilnadu. Cholesterol, span 20, span 60, span 80, methanol, chloroform were obtained from BurdoyneBurbidges Mumbai.

Preparation and Evaluation of Loratadine Niosomes

Preparation of standard curve of loratadine14

5 mg of loratadine was accurately weighed and dissolved in a small portion of methanol and made the volume up to 100 ml with double distilled water to give a concentration of 50µg/mL. Different volumes (1,2,3,4,5,6,7,8,9 and 10 mL) of the prepared solution were transferred to volumetric flasks. Each flask was made up to 25 mL with double distilled water to get concentrations 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 µg/mL. The different concentrations were analyzed spectrophotometrically a wavelength ranging from 200 nm to 400 nm to determine the wavelength of maximum absorbance. The calibration curve of loratadine was plotted by using the absorbance of different concentration of drug at 248 nm versus concentration.

Preparation of niosomes4

Niosomes were prepared using lipid film hydration technique with various concentrations of span and cholesterol. Surfactant ( span 20, 60, 80 ), cholesterol and drug were accurately weighed and dissolved in 15 mL ofchloroform : methanol mixture (2:1 v/v ratio). [33] The formula was shown in Table 1 Above mixture was sonicated for 1 min. Then it was vortexed in a round bottom flask at a temperature of 55-65°C to remove the solvent for about 30 min. The formed thin lipid layer was hydrated with 10 mL of 7.4 Phosphate buffer at 60°C for 1hr.7the resultant dispersion was cooled in an ice bath then left for 4hrs at room temperature for complete hydration and stored at 4°C overnight before use.6

Table1: Composition of developed niosomes

Formulation code Surfactant

Used

Weight taken ( in mg ) Surfactant:

Cholesterol

ratio

Drug Surfactant Cholesterol
F1 Span 20 100 100 100 1 : 1
F2 100 200 100 2 : 1
F3 100 100 200 1 : 2
F4 100 200 200 2 : 2
F5 Span 60 100 100 100 1 : 1
F6 100 200 100 2 : 1
F7 100 100 200 1 : 2
F8 100 200 200 2 : 2
F9 Span 80 100 100 100 1 : 1
F10 100 200 100 2 : 1
F11 100 100 200 1 : 2
F12 100 200 200 2 : 2

Evaluation of niosomes

Vesicle size of niosomes4

Vesicle size of each formulation was determined by an optical microscope. Each formulation was spread uniformly on a glass slide and observed under the 100X magnification optical lens.

Vesicle shape of niosomes4,8

The shape and morphological characters were obtained by SEM photographs of the niosomes. The formulations were placed into circular aluminium stubs using double adhesive carbon tape and coated with gold in HITACHI ION SPUTTER E-1010 vacuum evaporator, it was observed in HITACHI SU6600 FE SEM (field emission scanning electron microscope) having acceleration voltage of 10.0kv and magnification of 60.0k-100.0k 

Entrapment efficiency(EE%)9,10

Entrapment efficiency of niosomes was determined by centrifugation method where the niosomal dispersion was centrifuged at 12000 rpm for 90 min. The supernatant layer was separated and diluted using 7.4 phosphate buffer. Then determined the unentrapped drug spectrophotometrically. The percentage of entrapment efficiency was calculated using following equation.7

In-vitro drug release6,15

The in-vitro drug release profile of niosomal dispersion was investigated using semipermeable cellophane membrane. The membrane which was previously soaked in 7.4 phosphate buffer and glycerin was stretched over the open end of diffusion tube, made watertight by a rubber band. Added niosomal dispersion equivalent to 20 mg into the diffusion tube having diameter 2.5cm which acted as donor compartment.8The glass tube was immersed in a vertical position inside a 100mL beaker containing 7.4 phosphate buffer (50 mL). The temperature was maintained at 37±0.5°C and stirred at 100 rpm speed using magnetic stirrer. Samples were withdrawn from the receptor compartment at specified time intervals 1,2,3,4,5,6,7,8,9,10,11 and 12 hours.11Each time immediately after the removal of sample, the medium was replaced with fresh 7.4 phosphate buffer. The samples were analyzed for drug release spectrophotometrically at 248 nm.

RESULTS AND DISCUSSION  

Preparation of standard curve of loratadine

The slope of  thestandard plot of loratadine was found to be 0.047 with r2 0.999, which is shown in  figure 1. 

Fig 1: Standard plot of  loratadine

Evaluation of niosomes

Vesicle size of niosomes

The mean particle size of the formulations was shown in the table 2 and figure 2.

The vesicle size was determined for 50 niosomes in each formulation. It was found that as cholesterol content increased vesicle size also increases. As surfactant content increased vesicle size was found to be decreasing. The vesicle size of niosomes prepared by span 60 showed the lowest size than other. The order of particle size distribution of types of surfactant was span 20 > span 80 > span 60

 Table2 :Evaluation values of noisome 

SL NO Formulation Code Mean Particle Size(µm) SD

( n=3)

%Entrapment Efficiency % Cumulative

Drug Release  SD

 ( n=3)

1 F1 5.60.22 91.1 87.94570.9444
2 F2 4.420.05 93.4 90.37760.5540
3 F3 7.480.30 85.9 83.92020.4324
4 F4 6.510.45 88.28 82.51480.5384
5 F5 4.030.20 94 90.12020.5612
6 F6 3.490.17 94.9 92.61800.90785
7 F7 5.990.61 93.11 82.96700.9047
8 F8 5.650.29 90.8 86.56800.3878
9 F9 5.020.08 85.67 89.67340.3534
10 F10 4.090.18 87.33 88.32661.1113
11 F11 6.250.32 81.6 80.19680.6965
12 F12 5.740.44 83.2 83.49780.7549

Fig 2: Mean particle size of niosomes

Vesicle shape of niosomes

It was found that all 12 formulations has excellent morphology and spherical in structure. Which indicates that the formation of niosomes. Photographs are shown in the figure 

Entrapment efficiency(EE%)

Fig 3 : SEM Photograph of loratadineniosomes

The entrapment efficiency of 12 formulations was shown in the table 2.It was found to be in the range of 80-96 % . Higher entrapment efficiency of the vesicles of span 60 is predictable because of its higher alkyl chain length. The entrapment efficiency was found to be higher with the formulation no. The niosomal formulations having high surfactant concentration (F2, F6 and F10) have the higher entrapment efficiency which might be due to the high fluidity of the vesicles. F6 (94.9%), which shows higher entrapment of loratadine. It reveals that the HLB value of surfactant plays an important role in entrapment efficiency. As HLB value of surfactants increasing, the encapsulation efficiency also found to be increasing. But the variation in gel-liquid transition temperature may affect the entrapment efficiency of span 20.The order of entrapment efficiency was span 60 > span 20 > span 80. It was also observed that very high cholesterol content (F3, F11) had a lowering effect on drug entrapment in the vesicles (85.9 %, 81.6%). This could be due to the fact that cholesterol beyond a certain level started disrupting the regular bi-layered structure leading to loss of drug entrapment.

In-vitro drug release

The release study was conducted for all the 12 formulations, which is shown in the table 2 and figure. The formulations were found to have provided approximately 90% release within a period of 12 hours. The formulations which had high cholesterol ratio (F3, F7, F11) were found to reduced drug release. The slower release of drug from multilamellar vesicles may be attributed to the fact that multilamellar vesicles consist of several concentric spheres of bilayer separated by aqueous compartment. The three formulations F2, F6, and F9 were found to give a cumulative release of 90.37 %, 92.61 % and 89.67 % respectively over a period of 12 hrs, which indicating that the surfactant content increasing the drug release of BCS class II drug. From the 12 formulations, formulation F6 showed highest drug release, which was prepared by using span 60.Optimum HLB value also playing an important role in the drug release.

Fig 4:In-vitro release profile of niosomes formulated using span 20

Fig 5: In-vitro release profile of niosomes formulated using span 60

Fig 6:In-vitro release profile of niosomes formulated using span 80

 CONCLUSION

To conclude, the findings of the present investigation was an evidence that, the non-ionic surfactants and cholesterol was affecting the BCS class II drug loaded niosomes in different ways. Niosomes formulated using span 60 have shown the best drug release profile, smallest vesicle size, and entrapment efficiency.The optimum HLB value of the surfactant span 60 made this formulation better than others. The surfactant content increasing entrapment efficiency and in-vitro drug release. In the same time, cholesterol content was decreasing entrapment efficiency and drug release of loratadine loaded niosomes. Finally, it can be concluded that the surfactants and cholesterol plays an important role upon the lipophilic drug loaded niosomes.

ACKNOWLEDGEMENT

The author expresses sincere thanks to the Kerala University of Health Sciences, management, and principal of Rajiv Gandhi Institute of Pharmacy for providing a platform for the research work. We also thank Caplin.laboratories.Ltd Tamilnadu for providing gift samples for this work

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