Liposomes

lLiposomes

1. LIPOSOMES PRESENTED BY K. C. ANURADHA

2. INDEX Introduction Advantages Disadvantages Types Methods of Preparation Evaluation Application

3. INTRODUCTION Liposomes : Liposomes are microscopic sealed structures in which the aqueous compartment is enclosed by one or more phospholipid bilayers . These carry the drug and release it at the specific site of action .

4. These liposomes have proved to be excellent carriers for drugs, as these are bio degradable, inert and their lipid bilayers are similar in composition to the biological memberanes .

5. Advantages

6. Disadvantages

7. TYPES OF LIPOSOMES

8. METHODS OF PREPARATION

9. METHODS OF LIPOSOME PREPARATION

10. Mechanical dispersion methods:

11. Solvent dispersion method:

12. Detergent removal method:

13. General method of preparation

14. Hand Shaken MLVs (In 250ml RBF) (Flush with nitrogen)

15. Pro- Liposome (Evaporation) (Stand over night at room temperature)

16. Micro emulsification liposomes (MEL)

17. Sonicated unilamellar vesicles

18. To increase size of liposomes : Freeze thaw sonication

19. pH induced vesiculation

20. EVALUATION Evaluation tests are used used to ensure their predictable in –vivo and in- vitro performance. Evaluation tests are classified into three broad categories which include: 1. physical 2. chemical 3. biological tests

21. Particle size and particle size distribution Explains physical stability These can be determined by the following methods Laser Light Scattering Transmission Electron Microscopy

22. 1. LASER LIGHT SCATTERING Laser light scattering is a very simple and rapid method which requires expensive instrumentation. In his method, a light of suitable wavelength is passed through a lipodial suspension. The intensity of light scattered by the liposomes is proportional to their diameter. Therefore, measuring the fluctuations in scattered light helps to indicate the particle size of liposomes .

23. 2. Transmission Electron Microscopy The best method for determining the particle size of individual liposomes is electron microscopy. However, it requires high vaccum , is time consuming and may bring about changes in the structure of the liposome. Freeze fracture electron microscopy is found to be effective for evaluating large- size vesicles. This technique is also helpful in examining the morphological changes that occur in liposomes when they undergo phase transition

24. Phase Behaviour Liposomes at transition temperature undergo reversible phase transition i.e., the polar head groups in gel state become disordered to form the liquid crystalline state. The phase behaviour of liposomes can be determined by differential scanning calorimetry (DSC). The transition temperature is indicative of stability .

25. Therapeutic applications Liposomes as drug/ protein delivery vehicles. Liposomes in antimicrobial, antifungal and antiviral therapy. Liposomes in tumour therapy. Liposomes in gene delivery. Liposomes in immunology. Liposomes as radiopharmaceutical and radio diagnostic carrier Liposomes in cosmetic and dermatology. Liposomes in enzyme immobilization and bioreactor.