NIOSOMES

Presented By :

V. Bhargava Reddy

M.Pharmacy(‖ Sem)

Department of Pharmaceutics

College of Pharmaceutical science

S.K.University

Anantapur1

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Contents

• Introduction• Advantages• Structure of Niosomes• Types of niosomes • Factors affecting formation of niosomes• Method of preparation• Characterization of Niosomes• Applications

INTRODUCTION– Niosomes are a novel drug delivery system, in which the medication

is encapsulated in a vesicle. – The vesicle is composed of a bilayer of non-ionic surface active

agents and hence the name niosomes.

– The niosomes are very small, and microscopic in size. Their size lies in the nanometric scale.

– Niosomes are unilamellar or multilamellar vesicles.The vesicle is composed of a bilayer of non-ionic surface active agents and hence the name niosomes.

– A diverse range of materials have been used to form niosomes such as sucrose ester surfactants and polyoxyethylene alkyl ether surfactants, alkyl ester, alkyl amides, fatty acids and amino acid compound.

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ADVANTAGES OF NIOSOMES

• High patient compliance in comparison with oily dosage forms.

• Accommodate drug molecules with a wide range of solubilities.

• Characteristics of the vesicle formulation are variable and controllable

• Osmotically active and stable, as well as they increase the stability of entrapped drug.

• Biodegradable, biocompatible and nonimmunogenic.

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Structure of Niosomes

– Niosomes are microscopic lamellar structures which are formed on the admixture of non-ionic surfactant of the alkyl or dialkyl polyglycerol ether class and cholesterol with subsequent hydration in aqueous media.

– The bilayer in the case of niosomes is made up of non-ionic surface active agents rather than phospholipids as seen in the case of liposomes.

– Most surface active agents when immersed in water yield micellar structures, however some surfactants can yield bilayer vesicles which are niosomes. Niosomes may be unilamellar or multilamellar depending on the method used to prepare them.

– The niosome is made of a surfactant bilayer with its hydrophilic ends exposed on the outside and inside of the vesicle, while the hydrophobic chains face each other within the bilayer.

– Hence, the vesicle holds hydrophilic drugs within the space enclosed in the vesicle, while hydrophobic drugs are embedded within the bilayer itself.

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• The figure below will give a better idea of what a niosome looks like and where the drug is located within the vesicle

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TYPES OF NIOSOMAL SYSTEM•1. Small unilamellar vesicles- (SUV, size -0.025-0.05 μm) are commonly produced by sonication, and French Press procedures. Ultrasonic electrocapillary emulsification or solvent dilution techniques can be used to prepare SUVs.

• 2. Multilamellar vesicles- (MLV, size >0.05 μm) exhibit increased-trapped volume and equilibrium solute distribution, and require hand-shaking method. They show variations in lipid compositions.

• 3. Large unilamellar vesicles- (LUV, size >0.10 μm), the injections of lipids solubilised in an organic solvent into an aqueous buffer, can result in spontaneous formation of LUV. But the better method of preparation of LUV is Reverse phase evaporation, or by Detergent solubilisation method

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FACTORS AFFECTING FORMATION OF NIOSOMES• Drug• Amount and type of surfactant• content and charge• Methods of preparation• Nature of surfactants• Structure of surfactants• Membrane composition• Nature of encapsulated drug• Temperature of hydration• Type of Surfactants• Surfactant/Lipid and Surfactant/Water Ratios• Other Additives• Nature of the Drug• Resistance to osmotic stress

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Method of preparationA. Ether injection method• Introduce a solution of surfactant dissolved in diethyl ether into warm

water maintained at 60°C. • Surfactant mixture in ether is injected through 14-gauge needle into an

aqueous solution of material.• Vaporization of ether leads to formation of single layered vesicles.

Depending upon the conditions used, the diameter of the vesicle range from 50 to 1000 nm.

B .  Hand shaking method (Thin film hydration technique) • Surfactant and cholesterol are dissolved in a volatile organic solvent• Organic solvent is removed at room temperature using rotary

evaporator leaving a thin layer of solid mixture deposited on the wall of the flask

• Dried surfactant film can be rehydrated with aqueous phase at 0-60°C with gentle agitation. This process forms typical multilamellar niosomes.

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C . Sonication• Aliquot of drug solution in buffer is added to the surfactant/cholesterol

mixture in a 10-ml glass vial• Mixture is probe sonicated at 60°C for 3 minutes using a sonicator with

a titanium probe to yield niosomes.

D. Micro fluidization.• Micro fluidization is a recent technique used to prepare unilamellar

vesicles of defined size distribution. • This method is based on submerged jet principle in which two fluidized

streams interact at ultra high velocities, in precisely defined micro channels within the interaction chamber.

• The impingement of thin liquid sheet along a common front is arranged such that the energy supplied to the system remains within the area of niosomes formation.

• The result is a greater uniformity, smaller size and better reproducibility of niosomes formed.

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E. Multiple membrane extrusion method • Mixture of surfactant, cholesterol and dicetyl phosphate in chloroform is

made into thin film by evaporation• The film is hydrated with aqueous drug solution and the resultant

suspension extruded through polycarbonate membranes

F. Reverse Phase Evaporation Technique• Cholesterol and surfactant (1:1) are dissolved in a mixture of ether and

chloroform.• An aqueous phase containing drug is added to this and the resulting two

phases are sonicated at 4-5°C. • organic phase is removed at 40°C under low pressure• The resulting viscous niosome suspension is diluted with PBS and heated

on a water bath at 60°C for 10 min to yield niosomes.

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G. Trans membrane pH gradient (inside acidic) Drug Uptake Process (remote Loading)• Surfactant and cholesterol are dissolved in chloroform. The

solvent is then evaporated under reduced pressure to get a thin film on the wall of the round bottom flask. The film is hydrated with 300 mM citric acid (pH 4.0) by vortex mixing. The multilamellar vesicles are frozen and thawed 3 times and later sonicated. To this niosomal suspension, aqueous solution containing 10 mg/ml of drug is added and vortexed. The pH of the sample is then raised to 7.0-7.2 with 1M disodium phosphate. This mixture is later heated at 60°C for 10 minutes

to give niosomes.

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Recently Advanced Techniques

A. Bubble Method :• It is novel technique for the one step preparation of liposomes and

niosomes without the use of organic solvents. • The bubbling unit consists of round-bottomed flask with three

necks positioned in water bath to control the temperature. • Water-cooled reflux and thermometer is positioned in the first and

second neck and nitrogen supply through the third neck. • Cholesterol and surfactant are dispersed together in this buffer (pH

7.4) at 70°C, the dispersion mixed for 15 seconds with high shear homogenizer and immediately afterwards “bubbled” at 70°C using nitrogen gas.

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B.Formation of niosomes from proniosomes :– To create proniosomes, a water soluble carrier such as sorbitol is first

coated with the surfactant. The coating is done by preparing a solution of the surfactant with cholesterol in a volatile organic solvent, which is sprayed onto the powder of sorbitol kept in a rotary evaporator. The evaporation of the organic solvent yields a thin coat on the sorbitol particles. The resulting coating is a dry formulation in which a water soluble particle is coated with a thin film of dry surfactant. This preparation is termed Proniosome.

– The niosomes can be prepared from the proniosomes by adding the aqueous phase with the drug to the proniosomes with brief agitation at a temperature greater than the mean transition phase temperature of the surfactant.

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Materials

• Surfactants :Surfactants are usually organic compound that are amphiphilic, meaning they contain both hydrophobic groups (their tails) and hydrophilic groups (their heads).

Nonionic sufactants : Fatty alcohols - cetyl alcohol

Polyoxyethylene glycol alkyl ethers , Glucoside alkyl ethers, Polyoxyethylene glycol octylphenol ethers, Polyoxyethylene glycol alkylphenol ethers, Glycerol alkyl esters, Polyoxyethylene glycol sorbitan alkyl esters, Sorbitan alkyl esters

• Cholesterol : Cholesterol, a natural steroid, is the most commonly usedmembrane additive and can be incorporated to bilayers at high molar ratios.

• Drug: Entrapment of drug in niosomes increases vesicle size, probably by interaction of solute with surfactant head groups, increasing the charge and mutual repulsion of the surfactant bilayers, thereby increasing vesicle size.

• Other Additives; dicethylphosphate(DCP) and stearyl amine (SA) have been used to produce charge in niosome formulations.

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Separation of Unentrapped Drug

1. Dialysis  The aqueous niosomal dispersion is dialyzed in a dialysis tubing

against phosphate buffer or normal saline or glucose solution.

2. Gel Filtration  The unentrapped drug is removed by gel filtration of niosomal

dispersion through a Sephadex-G-50 column and elution with phosphate buffered saline or normal saline.

3. Centrifugation The niosomal suspension is centrifuged and the supernatant is separated. The pellet is washed and then resuspended to obtain a niosomal suspension free from unentrapped drug.

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Characterization of Niosomes

a) Bilayer formation :Assembly of non-ionic surfactants to form bilayer vesicle is characterized by X-cross formation under light polarization microscopy.

b) Number of lamellae :It is determined by using NMR spectroscopy, small angle X-ray scattering and electron microscopy

c) Membrane rigidity : Membrane rigidity can be measured by means of mobility of fluorescence probe as function of temperature

d) Entrapment efficiency– After preparing niosomal dispersion, unentrapped drug is separated by

dialysis, centrifugation, or gel filtration as described above and the drug remained entrapped in niosomes is determined by complete vesicle disruption using 50% n-propanol or 0.1% Triton X-100 and analysing the resultant solution by appropriate assay method for the drug. Where,

– Entrapment efficiency (EF) = (Amount entrapped total amount) x 100

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b)Particle size analysis • Particle size analysis was done by scanning electronic

microscopy (SEM) using JEOL JSM-T330A scanning microscope brass stab.

• The stabs were placed briefly in a drier and then coated with gold in an ion sputter.

• Pictures of niosomes were taken by random scanning of the stub and count.

• The diameter is about 30 niosomes was measured from the photomicrographs of each batch.

• Finally, average mean diameters were taken into consideration.

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c)In-vitro release study • Human cadaver skin (HCS) was obtained from ventral part of

forearm of 35 years old male corpse and was stored at 4°C. • HCS membrane was spread and punches it at approximately 3

cm2 area. Trimmed away the excessfat and sliced to 500 m thickness using a Daw’s derma tone.

• These slices were hydrated in pH 7.4 PBS for 24 hrs prior to use. The HCS were attached to Khesary cell (K.C., filled with 100 ml of PBS) and add 10 mg niosomal suspension on it.

• Finally, cell was immersed into the receptor compartment. The dermal surface was just flush to the surface of permeation fluid (PBS), which was maintain at 37°C 0.50°C and stirred magnetically at 50 r.p.m., aliquots were withdraw and replaced with the same volume of fresh buffer, at every sampling points and analyzed by U. V. Spectrophotometer method at 294 nm.

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d)Stability study

• All niosomal formulations were subjected to stability studies by storering at 4°C, 25°C and 37°C in thermostatic oven for the period of three months.

• After one month, drug content of all the formulations were checked by method discussed previously in entrapped efficiency parameter. In-vitro release studies of selected formulations were also carried out

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APPLICATIONSa) Anti-neoplastic treatment• Most antineoplastic drugs cause severe side effects.

Niosomes can alter the metabolism, prolong circulation and half life of the drug, thus decreasing the side effects of the drugs.

• Niosomal entrapment of Doxorubicin and Methotrexate (in two separate studies) showed beneficial effects over the unentrapped drugs, such as decreased rate of proliferation of the tumor and higher plasma levels accompanied by slower elimination.

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b) Leishmaniasis• Leishmaniasis is a disease in which a parasite of the genus

Leishmania invades the cells of the liver and spleen. Commonly prescribed drugs for the treatment are derivatives of antimony (antimonials), which in higher concentrations can cause cardiac, liver and kidney damage. Use of niosomes in tests made possible to administer higher levels of the drug specifically targeted to Leishmania affected cells without triggering side effects, and thus allowed greater efficacy in treatment.

c) Delivery of peptide drugs• Oral peptide drug delivery has long been faced with a

challenge of bypassing the enzymes which would breakdown the peptide. Use of niosomes to successfully protect the peptides from gastrointestinal peptide breakdown is being investigated.

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d) Use in studying immune response• Due to their immunological selectivity, low toxicity and

greater stability; niosomes are being used to study the nature of the immune response provoked by antigens.

e) Niosomes as carriers for haemoglobin• Niosomes can be used as carriers for haemoglobin within the

blood. The niosomal vesicle is permeable to oxygen and hence can act as a carrier for haemoglobin in anemic patients.

f) Transdermal drug delivery systems utilizing niosomes• One of the most useful aspects of niosomes is that they greatly

enhance the uptake of drugs through the skin. Transdermal drug delivery utilizing niosomal technology is widely used in cosmetics, in fact, it was one of the first uses of the niosomes. Topical use of niosome entrapped antibiotics to treat acne is done. The penetration of the drugs through the skin is greatly increased as compared to un-entrapped drug. 23

g) Localized drug action• Drug delivery through niosomes is one of the approaches to

achieve localized drug action, since their size and low penetrability through epithelium and connective tissue keeps the drug localized at the site of administration.

• Localized drug action results in enhancement of efficacy of potency of the drug and at the same time reduces its systemic toxic effects e.g. Antimonials encapsulated within niosomes are taken up by mononuclear cells resulting in localization of drug, increase in potency and hence decrease both in dose and toxicity.

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Comparison of Niosomes v/s Liposomes

– Niosomes are different from liposomes in that they offer certain advantages over liposomes.

– Liposomes face problems such as – they are expensive, their ingredients like phospholipids are chemically unstable because of their predisposition to oxidative degradation, they require special storage and handling and purity of natural phospholipids is variable.

– Niosomes do not have any of these problems. Also since niosomes are made of uncharged single-chain surfactant molecules as compared to the liposomes which are made from neutral or charged double chained phospholipids, the structure of niosomes is differentfrom that of liposomes.

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– However Niosomes are similar to liposomes in functionality. Niosomes also increase the bioavailability of the drug and reduce the clearance like liposomes.

– Niosomes can also be used for targeted drug delivery, similar to liposomes. As with liposomes, the properties of the niosomes depend both- on the composition of the bilayer, and the method of production used.

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