NIOSOMES AS CARRIER (IN TRANSDERMAL DRUG DELIVERY)

CONTENTS

•INTRODUCTION

•SALIENT FEATURES

•STRUCTURE OF NIOSOME

•COMPONENTS

•PREPARATION METHODS

•CHARACTERIZATION

•Role of NIOSOMES IN TRANSDERMAL DRUG DELIVERY

• PRODUCTS

•References

INTRODUCTION

Transdermal drug delivery is problematic as the skin acts as a natural

barrier.

Therefore several methods have been assessed to increase the rate.

One of the approaches is the use of niosomes.

Niosomes are microscopic lamellar structures formed on admixture of non-ionic

surfactant and cholesterol with subsequent hydration in aqueous media.

SALIENT FEATURES:

They are osmotically active and stable.

They increase the stability of the entrapped drug

Handling and storage of surfactants do not require any special conditions

Can increase the oral bioavailability of drugs

Can enhance the skin penetration of drugs

They can be used for oral, parenteral as well as topical use

contd.

SALIENT FEATURES

The surfactants are biodegradable, biocompatible, and non-immunogenic .

Improve the therapeutic performance of the drug by protecting it from the

biological environment and restricting effects to target cells.

STRUCTURE:

In the surfactant bilayer hydrophilic ends exposed

on the outside and inside of the vesicle, while the hydrophobic chains face

each

other within the bilayer.

The vesicle holds hydrophilic drugs within the space enclosed in the

vesicle, while hydrophobic drugs are embedded within the bilayer itself.

COMPONENTS:

The main components of niosomes are Non ionic surfactants Cholesterol Water Drug

The association of non-ionic surfactant monomers into vesicles on hydration is a result of the interfacial tension between water and the hydrocarbon portion of the amphiphile which causes these groups to associate. Simultaneously, the steric, hydrophilic and/or ionic repulsion between the head groups ensures that these groups are in contact with water.

These two opposing forces result in a molecular assembly.

Various non ionic surfactants used are

Sorbitan monostearate (span 60)Polyoxyethylene 2 stearylether (brij 72)Polyoxyethylene sorbitan monostearate (tween 61)Glyceryl monostearatePolyoxyethylene 4 laurylether (brij 30) Di glyceryl monolaurate Tetra glyceryl monolaurate

The mean size of niosomes increases regularly with increase in the HLB from Span 85(1.8) to span 20(8.6).

Vesicles obtained from the long alkyl chain (C18) surfactants give higher entrapment efficiency and were more stable than the shorter alkyl chain (C12) surfactants.

The effect of niosome forming surfactant

Increased hydrophilicity causes

Increased leakage of low molecular weight drugs from aqueous compartments.Decreased stability of niosome preparation Improved transdermal delivery of hydrophobic molecules.

Increased hydrophobicity causes

Decreased leakage of low molecular weight drugs from aqueous compartments.Increased encapsulationIncreased stability of niosome preparation Decreased toxicity

Cholesterol content Inclusion of cholesterol in niosomes increases its diameter and entrapment efficiency.

Presence of cholesterol in bilayer reduces permeability and improves retention of solute.

1:1 molar ratio of the surfactants to cholesterol is generally used.

PREPARATION METHODS

Ether injection method

Hand shaking method

Reverse phase evaporation technique

Trans membrane pH gradient Drug Uptake Process

The “Bubble” Method

Sonication

Micro fluidization

Multiple membrane extrusion method

Formation of niosomes from proniosomes

CHARACTERIZATION

Entrapment efficiency

Vesicle diameter

light microscopy,

photon correlation microscopy ,

freeze fracture electron microscopy.

In-vitro release

NIOSOMES IN TDDSDrug molecules in contact with the skin surface can penetrate by three potential pathways: • The sweat ducts • sebaceous glands• stratum corneum

Ideal properties of a molecule penetrating stratum corneum are.

Aqueous solubility > 1mg/mlLipophilicity 10 < Ko/w < 1000Molecular weight < 500 DaltonsMelting Point < 200ºCpH of saturated aqueous solution pH 5-9 

MECHANISMS

Several mechanisms of niosomes to modulate drug transfer across skin are

Adsorption and fusion of niosomes onto the surface of skin.

The vesicles act as penetration enhancers to reduce the barrier properties of the stratum corneum.

The lipid bilayers of niosomes act as a rate-limiting membrane.

Niosomal products in TDDS areFlurbiprofen PiroxicamEstradiolLevonorgestrolNimesulideDithranolKetoconazoleEnoxacinKetorolac

REFERENCES

1. Ijeoma F. Uchegbu a, Suresh P. Vyas, Non-ionic surfactant based vesicles (niosomes) in drug delivery , International Journal of Pharmaceutics 172 (1998) 33–70.

2. Gregor Cevc, Lipid vesicles and other colloids as drug carriers on the skin, Advanced Drug Delivery Reviews 56 (2004) 675– 711.

3. Maria Manconi, Chiara Sinico, Donatella Valenti, Francesco Lai, Anna M. Fadda, Niosomes as carriers for tretinoin III. A study into the in vitro cutaneous delivery of vesicle-incorporated tretinoin, International Journal of Pharmaceutics 311 (2006) 11–19

4. RAJNISH ARORA, AND C. P. JAIN, ADVANCES IN NIOSOME AS A DRUG CARRIER, Asian journal of pharmaceutics,vol1,issue 1,2007.

5. Alok namedo,n.k.jain,niosomes as drug carrier,Indian J.pharm. Sci., 1996,58(2),41-46.6. www.pharmainfo.net

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