Niosomes and pharmacosomes

Presentation byP.Soujanya

256212886026 M.Pharm(pharmaceutics)

Mallareddy College of Pharmacy

Under the esteemed guidance of Mrs.Yasmin begum(M.Pharm, Ph.D)

CONTENTS OF NIOSOMES

INTRODUCTION STRUCTURE OF NIOSOMES ADVANTAGES MECHANISM OF NIOSOMES FORMULATION CHARACTERIZATION EVALUATION THERAPEUTIC APPLICATIONS MARKETED PRODUCTS

INTRODUCTION

• Niosomes are non-ionic surfactant vesicles obtained on hydration of synthetic nonionic surfactants, with or without incorporation of cholesterol or other lipids.

• They are vesicular systems similar to liposomes that can be used as carriers of amphiphilic and lipophilic drugs

• These are less toxic and improves the therapeutic index of drug by restricting its action to target cells

• Niosomes are a novel drug delivery system, in which the medication is encapsulated in a vesicle.

• 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.

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 liposome.

• 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.

• Examples of non ionic surfactants used in the preparation of niosomes :

1.Sorbitan alkyl ester (spans)2.Polyoxyethylene glycol Sorbitan alkyl ester

(polysorbates)3.Polyoxyethylene glycol alkyl ether (Brij)4.Fatty alcohols example cetyl alcohol , stearyl alcohol5.Glycerol alkyl ester example glyceryl laurate

• Bilayer formation : Hydrophobic chains of surfactants are responsible for bilayer formation.

It is explained by critical packaging parameter for surfactants Pc. It is given by

Pc = v/ao.lc• the minimum interfacial area occupied by the head group- ao; • the volume of the hydrophobic tail (s)- v; • the maximum extended chain length of the tail in the micelle core-lc. If Pc is < 0.33 the expected aggregate structure is spherical micelles.If Pc is 0.5 to 1 the expected aggregate structure is vesicle bilayer

structure.

* So formed bilayer vesicle mimic biological cell membrane and have similar interactions which help in adsorption of vesicles on the cell membranes.

Role of cholesterol

• Cholesterol, a natural steroid, is the most commonly used membrane additive

• Stabilize the system against the formation of aggregates by repulsive steric or electrostatic effects

• Prevents the transition from the gel state to liquid phase in niosomes systems by increasing hydrophobic interactions.

• Niosomes become less leaky as cholesterol seals the pores or spaces on the bilayer.

Cholesterol

SmallUnilamellarVesicle(SUV)

LargeUnilamellarVesicle(LUV) Multilamellar

vesicles(MLV)

Typical Size Ranges: ULV: 20-50 nm – MLV:100-1000 nm

Advantages of niosomes

• They possess an infrastructure consisting of hydrophobic and hydrophilic moieties together and as a result can accommodate drug molecules with a wide range of solubilities

• They improve the therapeutic performance of the drug molecules by delaying the clearance from the circulation, protecting the drug from biological environment, and restricting effects to target cells

• Handling and storage of surfactants requires no special

conditions.

• Enhance skin penetration of drugs. • The vesicle suspension being water based offers greater

patient compliance over oil based systems

• Act as a depot to release drug slowly

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

Advantages of niosomes over liposomeso In case of liposomes ,Ester bonds of phospholipids are easily

hydrolyzed, at low pH

o Peroxidation of unsaturated phospholipids. oAs liposomes have purified phospholipids they are to be

stored and handled at inert(N2) atmospheres where as Niosomes are are made of non ionic surfactants and are easy to handle and store.

oPhospholipid raw materials are naturally occurring substances and as such require extensive purification thus making them costly

Mechanism of Niosome

1.Acts as Permeation enhancer In Topical preparation : Increases penetration of drug by destabilizing the stratum corneum.

2.Acts as targeting agent : drug targeting includes both passive targeting and active targeting.

•Passive targeting seen incase of solid tumors.

• Active targeting includes : Ligand mediated targeting and physical mediated targeting (pH or temp changes)

Stealth niosomes

• Any foreign matter is recognized by human immune system i.e, macrophages engulf them and provide protection.

• Opsonins are proteins which help macrophages in engulfing the foreign matter ( including niosomes) .

• Opsonins attach on niosomes and helps macrophages to recognize the niosomes for phagocytosis, Which result in degradation of niosomal preparation.

• Stealth niosomes are one which prevent the attachment of opsonins on it.

• Stealth niosomes are prepared by coating the niosomes with hydrophillic and non ionic polymers for ex PEG and its derivatives.

• Absence of electrostatic and hydrophobic forces and also steric hindrance of PEG opsonins cannot bind to niosomes.

• PEG have flexible and extended conformation which prevents the opsonins in binding to the niosomes by creating strong repulsive forces.

Formulation of niosomes

1.Ether injection method.

It is essentially based on slow injection of surfactant : cholesterol in ether (20ml) through a 14 gauge needle at approximately 0.25 ml/min. into a pre-heated aqueous phase maintained at 60°C.

Vaporization of ether leads to formation of single layered vesicles. Later it results in the formation of a bilayer sheet, which eventually folds on itself to form sealed vesicles.

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

2.. Hand shaking method (Thin film hydration technique).

The mixture of vesicles forming ingredients like surfactant and cholesterol are dissolved in 10 ml of volatile organic solvent (diethyl ether, chloroform or methanol) in a round bottom flask.

The organic solvent is removed at room temperature (20°C) using rotary evaporator leaving a thin layer of solid mixture deposited on the wall of the flask.

The dried surfactant film can be rehydrated with aqueous phase by gentle agitation.

This process forms typical multilamellar niosomes. The liquid volume entrapped in vesicles appears to be small, i.e. 5-10%.

3. Sonication.

A typical method of production of the vesicles is by sonication of solution.

In this method an aliquot of drug solution in buffer is added to the surfactant/cholesterol mixture in a 10-ml glass vial.

The mixture is probe sonicated at 60°C for 3 minutes using a sonicator with a titanium probe to yield niosomes.

The method involves the formation of MLVs which are subjected to ultrasonic vibrations.

Probe sonicator - when the volume of sample is small. Bath sonicator - when the volume of sample is large. Vesicles obtained are unilamellar in shape .

*Care must be taken while working with temperature sensitive solute.

4.The “Bubble” Method. It is novel technique for the one step preparation of liposome 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

5.Reverse Phase Evaporation Technique (REV)

LUVs can also be prepared by forming a water in oil emulsion of surfactants and buffer in excess organic phase followed by removal of the organic phase under reduced pressure ( so called reverse phase evaporation)

The two phases are usually emulsified by sonication

The lipid or surfactant forms a gel first and subsequently hydrates to form vesicles. Free drug (unentrapped) is generally removed by dialysis.

Separation of unentrapped material from

niosomes

Dialysis

CentrifugationGel filtration

Filtration

Separation of Unentrapped Drug1. 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.

Characterization 1.Entrapment efficiency

After preparing niosomal dispersion, unentrapped drug is separated by dialysis and the drug remained entrapped in niosomes is determined by complete vesicle disruption using 50% n-propanol or water soluble marker 0.1% Triton X-100 and analysing the resultant solution by appropriate assay method for the drug.

2.Size, Shape and Morphology :Electron Microscopy and light scattering :- Morphological studies of

vesiclesGel chromatography : size distribution

3.Niosomal drugloading and encapsulation efficiency The niosomal aqueous suspension was ultracentrifuged,supernant was

removed and sediment was washed twice with distilled water in order to remove the adsorbed drug.

Amount of drug in niosomesEntrapment efficiency (%)= --------------------------------------------X 100 Amount of Drug used

4. Vesicle Suface ChargeDetermined by measurement of electrophoretic mobility and expressed in terms of zeta potential

5. Niosomal drug release

The simplest method to determine invitro release kinetics of the loaded drug is by incubating a known quantity of drug loaded niosomes in a buffer of suitable pH at 37°c with continuous stirring ,withdrawing samples periodically and analysed the amount of drug by suitable analytical technique.dialysis bags or dialysis membranes are commonly used to minimize interference.

Evaluation of Niosomes

In-vitro release : A method of in-vitro release rate study includes the use of

dialysis tubing. A dialysis sac is washed and soaked in distilled water. The

vesicle suspension is pipetted into a bag made up of the tubing and sealed.

The bag containing the vesicles is placed in 200 ml of buffer solution in a 250 ml beaker with constant shaking at 25°C or 37°C.

At various time intervals, the buffer is analyzed for the drug content by an appropriate assay method of vesicles during the cycle.

Franz diffusion cell:• In a Franz diffusion cell, the cellophane membrane is

used as the dialysis membrane. • The niosomes are dialyzed through a cellophane

membrane against suitable dissolution medium at room temperature.

• The samples are withdrawn at suitable time intervals and analyzed for drug content.

Limitations

• Aggregation on storage may be the drawback for the niosome preparation .

• To avoid this instability Proniosomes are discovered. Proniosomes are dry formulation of surfactant

coated carrier, which can be measured out as needed and rehydrated by brief agitation in hot water.Advantages:

• Convenience of storage, transport and dosing.• More stable formulations.• Being dry powders makes processing and packaging easier.

Method of formation

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.

THERAPEUTIC APPLICATIONS

TREATMENT OF NEOPLASIA

The anthracyclic antibiotic Doxorubicin, with broadspectrum anti tumour activity, shows a dose dependentirreversible cardio toxic effect.

The halflife of drug increased by its niosomal entrapment of the drug and also prolonged its circulation and its metabolisom altered

If the mice bearing S-180 tumour is treated with niosomaldelivery of this drug it was observed that their life spanincreased and the rate of proliferation of sarcomadecreased.Methotrexate entrapped in niosomes if administeredintravenously to S-180 tumour bearing mice results in totalregression of tumour and also higher plasma level andslower elimination.

• Treatment of mitochondrial disorders :

Drug should released intracellular and should be protected from lysosomal degradation. In this case niosomal preparation of medication (ubiquinone,ubiquinol) by using DOPE-PEG as coating material which prevents lysosomal degradation of the preparation.

• Treatment of vitiligo : Topical application of corticosteroids and calcium modulators using

niosomal preparation. Niosomes known to enhance the permeation and facilitate the drug

transport across the skin.

• Treatment of glaucoma : Ophthalmic preparations of a acetazolamide niosomal preparation

results in Increased corneal permeability and increases drug delivery.

Leishmaniasis therapy• Derivatives of antimony are most commonly prescribed drugs for the treatment of leishmaniasis. • These drugs in higher concentrations – can cause liver,

cardiac and kidney damage.

• Use of niosomes as a drug carrier showed that it is possible to overcome the side effects at higher

concentration also and thus showed greater efficacy in Treatment.

• Magnetic Niosomes acts as contrasting agent in MRI imaging.

• Niosomes as immunological adjuvant

List of Drugs formulated as Niosomes

Intravenous route Doxorubicin, Methotrexate, Sodium Stibogluconate, Vincristine, Flurbiprofen, , Indomethacin, Colchicine,Rifampicin, Tretinoin,Transferrin and Glucose ligands, Zidovudine, Insulin,Cisplatin, Amarogentin,Daunorubicin, Amphotericin B, 5-Fluorouracil, Camptothecin

Transdermal route Flurbiprofen, Piroxicam, EstradiolLevonorgestrol,Nimesulide,Dithranol, Ketoconazole, Enoxacin, Ketorolac

Ocular route Timolol Maleate, Cyclopentolate

Nasal route Sumatriptan, Influenza Viral Vaccine

Inhalation All - trans retinoic acids

Marketed formulations

• Lancome has come out with a variety of anti-ageing products which are based on niosome formulations .

Anti ageing cream consists of D-Contraxol it is said to reduce the depth of wrinkles by working on the neuro -transmitters responsible for muscle contraction

PHARMACOSOMES

INTRODUCTION:

• Pharmacosomes are the colloidal dispersions of drugs covalently bound to lipids, and may exist as ultrafine vesicular, micellar, or hexagonal aggregates, depending on the chemical structure of drug-lipid complex.

• Pharmacosomes are amphiphilic phospholipid complexes of drugs

bearing active hydrogen that bind to phospholipids.

• Pharmacosomes impart better biopharmaceutical properties to the drug, resulting in improved bioavailability.

• Pharmacosomes have been prepared for various non-steroidal anti-inflammatory drugs, proteins, cardiovascular and antineoplastic drugs.

• Developing the pharmacosomes of the drugs has been found to improve the absorption and minimize the gastrointestinal toxicity.

IMPORTANCE:

• Pharmacosomes have importance in escaping the tedious steps of removing the free unentrapped drug from the formulation.

• Pharmacosomes provide an efficient method for delivery of drug directly to the site of infection, leading to reduction of drug toxicity with no adverse effects and also reduces the cost of therapy by improved bioavailability of medication, especially in case of poorly soluble drugs.

• Pharmacosomes are suitable for incorporating both hydrophilic and lipophilic drugs.

• Entrapment efficiency is not only high but predetermined, because drug itself in conjugation with lipids forms vesicles

• There is no need of following the tedious, time-consuming step for removing the free, unentrapped drug from the formulation.

• Since the drug is covalently linked, loss due to leakage of drug, does not take place.

• No problem of drug incorporation

• Encaptured volume and drug-bilayer interactions do not influence entrapment efficiency, in case of pharmacosomes

• In pharmacosomes, membrane fluidity depends upon

the phase transition temperature of the drug lipid complex, but it does not affect release rate since the drug is covalently bound.

• The drug is released from pharmacosome by hydrolysis (including enzymatic).

• The physicochemical stability of the pharmacosome

depends upon the physicochemical properties of the drug-lipid complex.

• Following absorption, their conversion into active drug molecule depends to a great extent on the size and functional groups of drug molecule, the chain length of the lipids, and the spacer.

PREPARATION:

• Two methods have been used to prepare vesicles:

1. The hand-shaking method

2. The ether-injection method

• In the hand-shaking method, the dried film of the drug–lipid complex is deposited in a round-bottom flask and upon hydration with aqueous medium, readily gives a vesicular suspension.

• In the ether-injection method, an organic solution of the drug–lipid complex is injected slowly into the hot aqueous medium, wherein the vesicles are readily formed.

FORMULATION OF PHARMACOSOMES:• Drug salt was converted into the acid form to provide an active

hydrogen site for complexation.

• Drug acid was prepared by acidification of an aqueous solution of drug salt, extraction into chloroform, and subsequent recrystallization.

• Drug -PC complex was prepared by associating drug acid with an equimolar concentration of PC.

• The equimolar concentration of PC and drug acid were placed in a

100-mL round bottom flask and dissolved in dichloromethane.

• The solvent was evaporated under vacuum at 40°C in a rotary vacuum evaporator.

• The pharmacosomes were collected as the dried residue and placed in a vacuum desiccator overnight and then subjected to characterization.

EVALUATION OF PHARMACOSOMES:

• Solubility

• Drug content

• Differential scanning calorimetry

• X-ray powder diffraction (XRPD)

Solubility:

• To determine the change in solubility due to complexation, solubility of drug acid and drug-PC complex was determined in pH 6.8 phosphate buffer and n-octanol by the shake-flask method.

• Drug acid (50 mg) (and 50 mg equivalent in case of complex) was placed in a 100-mL conical flask. Phosphate buffer pH 6.8 (50 mL) was added and then stirred for 15 minutes.

• The suspension was then transferred to a 250 mL separating funnel with 50 mL n-octanol and was shaken well for 30 minutes.

• Then the separating funnel was kept still for about 30 minutes. Concentration of the drug was determined from the aqueous layer spectrophotometrically at 276 nm.

Drug content:

• To determine the drug content in pharmacosomes of drug (e.g.: diclofenac-PC complex), a complex equivalent to 50 mg diclofenac was weighed and added into a volumetric flask with 100 mL of pH 6.8 phosphate buffer.

• Then the volumetric flask was stirred continuously for 24 h on a magnetic stirrer. At the end of 24 h, suitable dilutions were made and measured for the drug content at 276 nm UV spectrophotometrically.

Differential scanning calorimetry (DSC):

• Thermograms of drug acid, phosphatidylcholine (80 %) and the drug -PC complex were recorded using a 2910 Modulated Differential Scanning Calorimeter V4.4E (TA Instruments, USA).

• The thermal behavior was studied by heating 2.0 ± 0.2 mg of each individual sample in a covered sample pan under nitrogen gas flow. The investigations were carried out over the temperature range 25–250 °C at a heating rate of 10 °C min–1.

X-ray powder diffraction (XRPD):

• The crystalline state of drug in the different samples was evaluated using X-ray powder diffraction. Diffraction patterns were obtained on a Bruker Axs- D8 Discover Powder X-ray diffractometer, Germany.

• The X-ray generator was operated at 40 kV tube voltages and 40 mA tube current, using lines of copper as the radiation source. The scanning angle ranged from 1 to 60° of 2q in the step scan mode (step width 0.4° min–1).

• Drug acid, phosphatidylcholine 80 % (Lipoid S-80) and the prepared complex were analyzed.

APPLICATIONS:

• The approach has successfully improved the therapeutic performance of various drugs i.e. pindolol maleate, bupranolol hydrochloride, taxol, acyclovir, etc.

• The phase transition temperature of pharmacosomes in the vesicular and Micellar state could have significant influence on their interaction with membranes.

• Pharmacosomes can interact with biomembranes enabling a better transfer of active ingredient. This interaction leads to change in phase transition temperature of biomembranes thereby improving the membrane fluidity leading to enhance permeations.

Conclusion• The concept of incorporating the drug into niosomes for a better

targeting of the drug at appropriate tissue destination .• They presents a structure similar to liposome and hence they can

represent alternative vesicular systems with respect to liposomes• Niosomes are thoughts to be better candidates drug delivery as

compared to liposomes due to various factors like cost, stability etc. Various type of drug deliveries can be possible using niosomes like targeting, ophthalmic, topical, parentral, etc.

• Vesicular systems have been realized as extremely useful carrier systems in various scientific domains. Over the years, vesicular systems have been investigated as a major drug delivery system, due to their flexibility to be tailored for varied desirable purposes.

• In spite of certain drawbacks, the vesicular delivery systems still play

an important role in the selective targeting, and the controlled delivery of various drugs.

• Researchers all over the world continue to put in their efforts in improving the vesicular system by making them steady in nature, in order to prevent leaching of contents, oxidation, and their uptake by natural defense mechanisms.

References:

• S.P. Vyas R.K.Khar, Targeted And Controlled Drug Delivery novel carrier systems ; niosomes (p no.249-276)

• N.K.JAIN , Controlled and Novel Drug Delivery; niosomes p no.(292-301)

• H.A. Lieberman, M.M. Rieger, and G.S. Banker, Pharmaceutical Dosage Forms: Disperse Systems p. 163.

• International Journal of Biopharmaceutics.2011;2(1):47-53; NIOSOMES FORMULATION AND EVALUATION

• Review article of PHARMACOSOMES: A Potential vesicular drug delivery system BY de pintu kumar,de arnab

• Review article of PHARMACOSOMES:opening new doors for drug delivery BY anu goyal