Liposomes

SEMINAR ON LIPOSOMES

1. SEMINAR ON LIPOSOME S Presented by: VENKATESH GOLI M. Pharm 1 st YEAR (Pharmaceutics) SVU COLLEGE OF PHARMACEUTICAL SCIENCES , TIRUPATI SRI VENKATESWARA UNIVERSITY , TIRUPATI

2. CONTENT S INTRODUCTION BASIC STRUCTURE DIFFERENCE BETEEN MICELLE AND LIPOSOME STRUCTURAL COMPONENTS FORMATION OF A LIPOSOME TYPES OF LIPOSOMES METHOD OF PREPARATION ADVANTAGES AND DISADVANTAGES APPLICATIONS

3. L IPOSO M ES Liposomes first described by Dr. A. D . B a ngham in 196 . who was studynig phospolipid bilayers and blood cloting . The Liposomes are sperical , microscopic vesicles composed of one or more concentric phospholipids bi-layer separated by aqueous buffer compartments known as “Liposomes”.. Liposomes is Greek words means ‘Lipo’ mean ‘Fat’ and ‘Somes’ mean ‘Body’. Their diameter ranges from 1 0nm to 10 , 00n m .

4. BASIC STRUTURE It has a bilayer membrane. Membranes are usually made of phospholipids , which are molecules that have a head group and a tail group. The head is attracted to water, and the tail, which is made of a long hydrocarbon chain, is repelled by water.

5. DIFFERENCE BETEEN MICELLE AND LIPOSOME MICELE Micelle is composed of a monolayer of amphipathic molecules (phospholipids). They are smaller in size than liposomes . Their size varies from 2-20nm. LIPOSOME Liposome is composed of a bilayer of amphipathic molecules (phospholipids). Depending upon their type, they vary in their sizes .

6. STRUCTURAL COMPONENTS The main components of the liposomes are : L I POSO M E PHOSPHOLIPIDS C H OL E ST R OL

7. A. Phospholipids Phospholipids are major structural components of biological membranes in human body, where 2 types of phospholipids exist i.e. phosphodiglycerides & sphingolipids. Phospholipids in liposomes are amphipathic in nature, i.e. , it has both hydrophobic and hydrophilic parts. The head of phospholipid is hydrophilic (water loving) whereas its tail is hydrophobic (water fearing).

8. B. Cholesterol Cholesterol by itself does not form bilayer structure. They are present within the phospholipids.

9. FORMATION OF A LIPOSOME In a cell , when the phospholipids are dispersed in water, one layer of the heads faces outside of the cell whereas another layer of the heads faces inside the cell. The hydrocarbon tails of one layer faces the hydrocarbon tails of another layer and combines to form bilayer. This bilayer then extends in the water to form a sheet which then curls in a liposome.

10. TYPES OF LIPOSOMES 1.UNILAMELLAR LI P O S OME/V E S I CL E S These are present in many sizes and consists of one bilayer. 2.MULTILAMELLAR LI P O S OME/V E S I CL E S These are larger in size upto micrometer with two to more bilayers.

11. TYPES OF LIPOSOMES TYPES OF UNILAMELLAR Unilamellar are of 3 types : Small unilamellar vesicles usually range from 20-100nm in size and consists 0ne bilayer. Large unilamellar vesicles are usually greater than 100nm in size with one bilayer. Giant unilamellar are greater than 1000nm in size and consists one bilayer. OLIGOLAMELLAR LI P O S OME/V E S I CL E S These are 0.1-1nm in size and consists of 5 bilayers

12. 10 Method of liposome preparation Passive loading techniques Mech a nic al dispersion methods. Hand shaking Sonication Micro- e m ulsific a t i on French pressure cell Solvent disp e rs ion methods. Ethanol injection Ether injection Double emulsion vesicles Reverse phase evaporation vesicles Dete r gent removal methods. Detergent Dialysis Column ch r o m a t o g ra p hy Dilution Active loading techniques

13. 1. M ECHANICAL DISPERSION METHODS . 11

14. LIPID FILM HYDRATION BY HAND SHAKING 12 Fig. Multilaminar vesicles (MLVs) formed by hand shaking technique

15. 2. S OLVENT DISPERSION METHOD 19

16. 3. D ETERGENT REMOVAL METHODS 15 The conc. of detergent at which micelles are formed is called as CMC.

17. A DVANTAGES Liposomes increased efficacy and therapeutic index of drug. Liposomes increased stability via. encapsulation. Provide selective passive targeting to tumour tissues. I m proved phar m acokine t ic e f fe cts (redu c ed elimination , increased circulation life time). Liposomes reduce the toxicity of the encapsulation. Facilitation of transport across membranes. 5

18. D ISADVANTAGES 22 Low solubility in water. S o m et i m es phospholi p id unde r goes oxi d ation and hydr o l y sis like reaction. Production cost is high.

19. AP P LIC A TIONS Liposomes are used in drug/protein delivery or medicines. Controlled and sustained drug release in situ. Enchanced drug solubization. In Cosmetology and dermatology. In cancer therapy.

20. Thank