LIPOSOME

THIS PDF FOR NOVEL DRUG DELIVERY

1. LIPOSOME NOVEL DRUG DELIVEY SYSTEM

2. INTODUCTION COMPOSITION OF LIPOSOME CLASIIFICATION MECHNISUM OF LIPOSOME FORMATION METHOD OF PREPARATION CHARACTERIZATION APPLICATION REFERANCES CONTENTS

3. WHAT IS A LIPOSOME

4. Liposomes are small artificial vesicles of spherical shape that can be created from cholesterol and natural nontoxic phospholipids. Due to their size and hydrophobic and hydrophilic character (besides biocompatibility),liposomes are promising systems for drug delivery. Those layers are referred to as lamellae. Generally, liposomes are definite as spherical vesicles with particle sizes ranging from 0.025nm to 2.5 micrometers. They consist of one or more lipid bilayers surrounding aqueous units, where the polar head groups are oriented in the pathway of the interior and exterior aqueous phases INTRODUCTION

5. STRUCTRAL COMPOSITION OF LIPOSOME

6. Liposome properties differ considerably with lipid composition, surface charge, size, and the method of preparation . Furthermore, the choice of bilayer components determines the ‘ rigidity ’ or ‘ fluidity ’ and the charge of the bilayer. For instance, unsaturated phosphatidyl choline species from natural source( soybean phosphatidylcholine) give much more permeable and less stable bilayers, whereas the saturated phospholipids with long acyl chains (for example, dipalmitoyl phosphatidylcholine) form a rigid, rather impermeable bilayer structure . It has been displayed that phospholipids impulsively form closed structures when they are hydrated in aqueous solutions. Such vesicles which have one or more phospholipid bilayer membranes can transport aqueous or lipid drugs, depending on the nature of those drugs. Because lipids are amphipathic (both hydrophobic and hydrophilic) in aqueous media, their thermodynamic phase properties and self assembling characteristics influence entropically focused confiscation of their hydrophobic sections into spherical bilayers.

7. On the other hand, self-aggregation of polar lipids is not limited to conventional bilayer structures which rely on molecular shape ,temperature, and environmental and preparation conditions but may self-assemble into various types of colloidal particles Liposomes are extensively used as carriers for numerous molecules in cosmetic and pharmaceutical industries .Additionally, food and farming industries have extensively studied the use of liposome encapsulation to grow delivery systems that can entrap unstable compounds (for example, antimicrobials, antioxidants, flavors and bioactive elements) and shield their functionality Liposomes can trap both hydrophobic and hydrophilic compounds, avoid decomposition of the entrapped combinations, and release the entrapped at designated targets . BENEFITS OF DRUG LOADING IN LIPOSOME FOR DRUG DELIVERY • Provides selective passive targeting to tumor tissues (Liposome). Increased efficacy and therapeutic index. Increased stability via encapsulation Reduction in toxicity of the encapsulated agents. Site avoidance effect Improved pharmacokinetic effects (reduced elimination, increased circulation life times).

8. CLASSIFICATION OF LIPOSOME

9. CLASSIFICATION OF LIPOSOMES Flexibility to couple with site specific ligands to achieve active targeting liposomes can be classified in terms of composition and mechanism of intracellular delivery into five types · Conventional liposomes; · pH-sensitive liposomes; · Cationic liposomes; · Immunoliposomes and · Long-circulating liposomes Liposomes are typically classified on the basis of their size and number of bilayers as follows: · Small unilamellar vesicles (SUV): 20 – 100 nm; · Large unilamellar vesicles (LUV): > 100 nm; · Giant unilamellar vesicles (GUV): > 1000 nm; · Oligolamellar vesicle (OLV): 100 – 500 nm and · Multilamellarvesicles (MLV): > 500nm.

10. Handling of liposomes The lipids used in the preparation of liposomes are unsaturated and hence susceptible to oxidation. Phospholipids can be stored at temperature range between -20 to -70°c to avoid oxidation reaction between these phospholipids. Liposomes were store in the dark, in glass vessels with a securely fastened cap . Figure :size of liposome

11. MECHNISUM FORMATION OF LIPOSOME

12. Transdermal drug delivery system (TDDS) is dosage form designed to deliver a therapeutically effective amount of drug across a patient’s skin. In order to deliver therapeutic agents through the human skin for systemic effects, the comprehensive morphological, biophysical and physicochemical properties of the skin are to be considered. Transdermal delivery provides a leading edge over injectables and oral routes by increasing patient compliance and avoiding first pass metabolism respectively. Transdermal delivery not only provides controlled, constant administration of drug, but also allows continuous input of drug with short biological half- lives and eliminates pulsed entry into systemic circulation, which often causes undesirable side effect Stratum corneum is the main barrier in the transdermal drug absorption. This is cause by the high order of the lipid bilayers that are located between the corneocytes. The barrier properties of stratum corneum can be modified inorder to improve the topical delivery of drug by using skin penetration enhancer, which loosen or fluidize the highly ordered bilayer structure . Stratumcorneum is composed of keratinocyts and inter corneocytematrix . In keratinocytes, cellular membranes account for50% of the dry mass and consist mainly of phosphatidylcholine and sphingomyelin. The inter corneocyte matrix is rich in phospholipids. Thus phospholipids are themain component of stratum corneum Mechanism of action of Liposomes

13. Percutaneus penetration of drugs is dependent on twofactors , partitioning of drugs between the skin and thevehicle and diffusion of drug in the stratum corneum. Forexample , in the case of phospholipid the role of changes indrug partitioning and bilayer fluidity are not known. Some phospholipid increase skin lipid / buffer distribution coefficients for the drugs Possible mechanism of action of liposomes as skin drug delivery systems. (a) is the free drug mechanism, (b) is the penetration enhancing process of liposome components, (c)indicates vesicle adsorption to and / or fusion with the stratum cornium and (d) illustrates intact vesicle penetration into or and through the intact skin Free Drug Mechanism . · According to this process, the drug permeates the skin independently after exiting from the vesicles

14. METHODS OF PREPARATION

15. The following method are used for the preparation of liposome: Passive loading techniques. Active loading techniques METHOD OF LIPOSOME PREPARATION AND DRUG LOADING:

16. LIPID FILM HYDRATION TCHNIQUES:STEPS : . The lipid must first be dissolved and mixed in an organic solvent to assure a clear and homogenous , mixture of lipid . Once the lipid are thoroughly mixed in the organic solvent , the solvent is removed to yield a lipid film. The lipid film is thoroughly dried to remove residual organic solvent by placing the vial or flask on vaccum pump overnight. Add an aqueous medium to container of dry lipid and agitate .(The temputure of hydrating medium shouled be above the 30liquied crystal transition temputure of lipid with the highest before adding to dry lipid. vigorous shaking mixing or stirring is highly recommended). The hydrating lipid suspension then was downsized by verity of techniques,including sonication or extrusion

17. In this method primarily a dispersion of phospholipids in water is prepared to get the MLVSand then obtained MLVS are treated with ultrasonic radiation to reduce the vesicle size. This method give small unilamellar vesicles having size range of 0.025- 0.05μm The two methods of sonication are:- · Probe ultrasonic disintegrator. · Bath ultrasonic disintegrator. Depending on the concentration, sonication from minute tohour generally is employed. The probe is employed for dispersion,which requires high energy in small volume while the bath is more suitable for large volume of diluted lipids. SONICATION

18. PURIFICATION OF LIPOSOMES liposomes are commonly purified by one of the following method: · Centrifugation · Dialysis · Gel filtration column chromatography Separation of liposomes by centrifugation method depends on size and composition of the bilayers. In dialysis method any standard technique may be used. It is also convenient method for studying the leakage of small molecule. In column chromatographic separation liposome membrane may bind or intact with surface of polydextran beads.

19. EVALUATION OF MODIFIED LIPOSOMES: 1. Particle Size Determination: The particle size of liposomes was determined by using Motic microscope. All the prepared batches of the liposomes were viewed under Motic microscope to study their size. Size of liposomal vesicles from each batch was measured by taking a small drop of liposomal dispersion on glass slide and average size of the liposomal vesicles was determine 2. Drug Entrapment Efficiency: Entrapment efficiency of liposomes was determined by centrifugation method. Aliquote (1ml) of liposomal dispersion was subjected to centrifugation on a laboratory centrifuge at 5000rpm for a period of 35min at controlled temperature of 4°C. The clear supernatant was removed carefully to separate the unentrapped drug and absorbance was recorded at 262nm. The sediment in the centrifugation tube was washed with acetonitrile thrice and it was diluted to 5ml with acetonitrile and the absorbance was recorded at262nm. A calibration curve was produced by making different concentration from (1μg/ml-10μ/10ml) with acetonitrile. Amount of the drug in supernatant and sediment gave a total amount of drug in 1ml dispersion. % Entrapment of drug was calculated by the follow formula: % Drug Entrapment = Amount of the drug in the sediment X 100 Total amount ofdrug

20. CHACTERIZATION

21. In-Vitro Release Study: An in vitro drug release study was performed using modified Franz diffusion cell. Dialysis membrane was placed between the lower cell reservoir and the glass cell top containing the sample and secured in place with a pinch clamp. Liposomal formulation 1ml was placed in donor compartment and the receptor compartment was filled with phosphate buffer pH7.4 (17ml). The diffusion cell was maintained at37+0.5°C with stirring at 500rpm throughout the experiment. 1ml of receptor fluid were withdrawn from the receiving compartment at30min for the period of 5 hours and replaced with 1ml fresh phosphate buffer pH7.4 solution and after the suitable dilution analyzed by spectrophotometer at λ max 262 nm. Zeta Potential: Particle size and size distribution measurements of the liposomal dispersions were performed using photon correlation spectroscopy (PCS). The average particle sizes (z-average size) were measured by photon correlation spectroscopy Malvern Zetasizer at 25 o C under a fixed angle of 90 o in disposable polystyrene cuvettes . Zeta potential was measured by using Zetasizer. Samples were placed in clear zeta cells and results were recorded. Before putting the fresh sample, cuvettes were washed with the methanol and rinsed using the sample to be measured before each experiment.

22. APPLICATION

23. Liposomes In Parasitic Diseases And Infections From the time when conventional liposomes are digested byphagocytic cells in the body after intravenous management, they areideal vehicles for the targeting drug molecules into thesemacrophages . Liposomes In Anticancer Therapy Numerous different liposome formulations of numerous anticancer agents were shown to be less toxic than the free drug . Anthracyclines are drugs which stop the growth of dividing cells by intercalating into the DNA and, thus, kill mainly rapidly dividing cells. Systemic Delivery After systemic (usually intravenous) administration , liposomesare typically recognized as foreign particles and consequentlyendocytosed by the mononuclear phagocytic system cells (MPS),mostly fixed kuppfer cells, in the liver and spleen. Liposomes canserve as an excellent drug-delivery vehicle to these cells. Intramuscular and subcutaneous injection of drug at anextravascular site leads depot formation to initiate a number of eventsthat collectively make up the absorption process (Jain et al., 2005).Prepared a multivesicular liposomal (MVL) drug delivery systemcomprising of acyclovir sodium, which forms a depot on intramuscular injection

24. Brain Delivery The delivery of therapeutic agents into the parenchyma of the brain is problematic because it has been virtually impossible to know with any certainty where infused material is going, and how much to infuse. (Krauze et al) use liposomes loaded with gadoteridol as a tracer that allows us to follow infusions in real-time on magnetic resonance imaging. This data suggests that real-time monitoring of liposomal drug infusion is likely to improve outcomes of clinical trials where convection-enhanced delivery is being used to target drugs to specific brain structures through limitation of systemic toxicity and reduction of side effects. Vaccine And Antigen Aelivery Oral vaccination requires a antigen delivery vehicle to protectthe antigen and to enhance translocation of the antigen to themucosa -associated lymphoid tissue. Liposomas have been widelyexploited as antigen delivery system for a variety of diseasesdescribes the protein or vaccine loaded liposomes using various combination of lipids, surfactant, and solvents for pulmonary delivery, oral delivery, vaginal and antigen delivery with advantage of low cost, greater stability, purity of raw material, ease of storage .

25. REFERANCES

26. Aulton E. Pharmaceutics: The Science of Dosage Form Design.1st edition, Churchill Livingston, Edinburgh. 2002:499-533. Akbarzadeh A, Sadabady R ,Davaran S. Liposome: classification, prepara tion , and applications , Nanoscale Research Letters 2013, 8 :102-115 Basu K, Lala S. Macrophage specific drug delivery in experimental leishmaniasis, Curr Mol Med. 2004; 4:681-685. Bhoga B, Chigiri S, Aukunru J, Shayeda P. Preparation, Characterization and Evaluation of Anti inflammatory Activity of Dexamethasone Topical Liposomal Gel Formulation, American journal of Pharmtech research .2015;5(4)3:15-331 Chein W. “NovelDrugDeliverySystems.”2ndedition,Marcel Dekker, New York. 1992;50: 301-381. Chandran S, prasanna P. targeting dopamine liposome to brain using polysorbate80for parkinson disease international journal of biosciences 2015 ;5:107-115. Dash S, Murthy N, Nath L, Chowdhury P. Kinetic modeling on drug release from controlled drug delivery systems. Acta Pol Pharm . 2010;67(3):217-223.

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