Liposomes are spherical vesicles composed of phospholipid bilayers that can encapsulate aqueous solutions. They can be used to deliver both hydrophilic and hydrophobic drug molecules by encapsulating them within the aqueous interior or embedding them within the phospholipid membrane respectively. Liposomes offer several advantages for drug delivery such as protecting drugs, altering pharmacokinetics and biodistribution, and promoting targeted drug delivery. However, liposomal drug formulations also present challenges including high production costs, stability issues, and the potential for new side effects. Ongoing research continues to aim to optimize liposome design and composition to improve drug encapsulation and release properties.

1. Naval Chaudhary 70700029 Liposomes: Improving drug delivery

2. Phospholipids Polar Head Groups Three carbon glycerol

4. A liposome encapsulates a region on aqueous solution inside a hydrophobic membrane; dissolved hydrophilic solutes cannot readily pass through the lipids. Hydrophobic chemicals can be dissolved into the membrane, and in this way liposome can carry both hydrophobic molecules and hydrophilic molecules. To deliver the molecules to sites of action, the lipid bilayer can fuse with other bilayers such as the cell membrane , thus delivering the liposome contents About the Liposomes :

5. Liposome Preparation Lipid in organic solvent solution Evaporation Extrusion (or sonication) Liposomes and unencapsulated SRB Lipid film Freeze/thaw cycles Gel filtration Purified liposomes Hydrate with sulforhodamine B (SRB) solution

6. Liposome Preparation

7. Liposome Preparation

8. Liposome Preparation

9. Liposome Preparation http://www.avantilipids.com

10. Liposome Preparation

11. Liposome Ingredients 45% DPPC dipalmitoylphosphatidylcholine 45% Cholesterol 5% DPPG dipalmitoylphosphatidylglycerol 5% DPPE dipalmitolyphosphatidylanolamine

13. Uses of Liposomes Chelation therapy for treatment of heavy metal poisoning Enzyme Replacement Diagnostic imaging of tumors Study of membranes Cosmetics Drug Delivery

15. Protection Decrease harmful side effects Pharmokinetics - efficacy and toxicity Changes the absorbance and biodistribution Change where drug accumulates in the body Protects drug Deliver drug in desired form Multidrug resistance Why Use Liposomes in Drug Delivery?

16. Release Affect the time in which the drug is released Prolong time -increase duration of action and decrease administration Dependent on drug and liposome properties Liposome composition, pH and osmotic gradient, and environment Why Use Liposomes in Drug Delivery?

17. Modes of Liposome/Cell Interaction Adsorption Endocytosis Fusion Lipid transfer

20. Current liposomal drug preparations Type of Agents Examples Anticancer Drugs Anti bacterial Antiviral DNA material Enzymes Radionuclide Fungicides Vaccines *Currently in Clinical Trials or Approved for Clinical Use Malaria merozoite, Malaria sporozoite Hepatitis B antigen, Rabies virus glycoprotein Amphotericin B* In-111*, Tc-99m Hexosaminidase A Glucocerebrosidase, Peroxidase Duanorubicin, Doxorubicin*, Epirubicin Methotrexate, Cisplatin*, Cytarabin Triclosan, Clindamycin hydrochloride, Ampicillin, peperacillin, rifamicin AZT cDNA - CFTR*

21. CFTR Gene Therapy Deliver cDNA of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) to epithelial tissue of respiratory system Fuse to cell membrane and incorporate cDNA into cell Clinical trials - no significant change in symptoms Now trying adeno associated virus Cationic liposome

23. Amphotericin B Side effects: nephrotoxicity, chills, and fevers Systemic fungal infections in immune compromised patients Fungizone - AmB with deoxycholate AmB - kills ergosterol-containing fungal cells, also kills cholesterol-containing human cells

24. No decrease in effectiveness of drug against fungi Liposomal Formulation of AmB Decrease in toxicity Exact Mechanism of liposomes not understood Cholesterol - only few %moles Phospholipid:AmB ratio Diffusion Lipid transfer AmB Lipid

25. Name Trade name Company Indication Liposomal amphotericin B Abelcet Enzon Fungal infections Liposomal amphotericin B Ambisome Gilead Sciences Fungal and protozoal infections Liposomal cytarabine Depocyt Pacira (formerly SkyePharma) Malignant lymphomatous meningitis Liposomal daunorubicin DaunoXome Gilead Sciences HIV-related Kaposi’s sarcoma Liposomal doxorubicin Myocet Zeneus Combination therapy with cyclophosphamide in metastatic breast cancer Liposomal IRIV vaccine Epaxal Berna Biotech Hepatitis A Liposomal IRIV vaccine Inflexal V Berna Biotech Influenza Liposomal morphine DepoDur SkyePharma , Endo Postsurgical analgesia Liposomal verteporfin Visudyne QLT, Novartis Age-related macular degeneration, pathologic myopia, ocular histoplasmosis Liposome-PEG doxorubicin Doxil / Caelyx Ortho Biotech , Schering-Plough HIV-related Kaposi’s sarcoma, metastatic breast cancer, metastatic ovarian cancer Micellular estradiol Estrasorb Novavax Menopausal therapy

27. Possibility of new side effects Doxil “hand and foot syndrome” Problems continued Efficacy CFTR

28. Studies with insulin show that liposomes may be an effective way to package proteins and peptides for use Clinical Trials for several liposomal formulations More studies on the manipulation of liposomes Future

29. References Journals Allen, Theresa M. "Liposomal Drug Formulations: Rationale for Development and What We Can Expect for the Future." Drugs 56: 747-756, 1998. Allen, Theresa M. "Long-circulating (sterically stabilized) liposomes for targeted drug delivery ." TiPs 15: 214-219, 1994. Allen, Theresa M. "Opportunities in Drug Delivery." Drugs 54 Suppl. 4: 8-14, 1997 Janknegt, Robert. "Liposomal and Lipid Formulations of Amphotericin B." Clinical Pharmacokinetics. 23(4): 279-291, 1992. Kim, Anna et al. "Pharmacodynamics of insulin in polyethylene glycol-coated liposomes." International Journal of Pharmaceutics. 180: 75-81, 1999. Quilitz, Rod. "Oncology Pharmacotherapy: The Use of Lipid Formulations of Amphotericin B in Cancer Patients." Cancer Control. 5:439-449, 1998. Ranade, Vasant V. "Drug Delivery Systems: Site-Specific Drug Delivery Using Liposomes as Carriers." Pharmacology. 29: 685-694, 1989. Storm, Gert and Daan J.A. Crommelin. "Liposomes:quo vadi?" PSTT 1: 19-31, 1998. Taylor, KMG and JM Newton. "Liposomes as a vecicle for drug delivery." British Journal of Hospital Medicine. 51: 55-59, 1994

30. Websites James, John S. "Doxil Approved for KS." www.immunet. org.imminet/atn.nsf/page/a-235-03. Wasan, Ellen. "Targeted Gene Transfer." Member.tripod.com/~rrishna/lipos1.html "Introduction to Controlled Drug Delivery Systems." www5.bae.ncsu.edu/bae/reearch/blak… k/otherprojects/drugDeliver_97/ http://www. Mssm.edu/medicine/thrombosis/phosphol.html "Doxorubicin." http://tirgan.com/adria.htm "Clinical Pharmacology Online." http://www.cponline.gsm.com/scripts/fullmono/showmono. "Drugstore.com" http://www.drugstore.com/pharmacy/prices/Amphotec. "Sequus' Doxil Becomes First Liposome Product Approved In U.S." www.slip.net/~mcdavis/ database/doxor_1 "Liposomes." www.collabo.com/liposom0.htm Paustin, Timothy. “Cellular Membranes.”www.bact.wisc.edu/microtextbook/bacterialstructure/Membranegen.html www.cbc.umn.edu/~mwd/cell_www/chapter2/membrane.html#PHOSPHOLIPIDS Books Jones, Macolm N. and Chapman, David. Micelles, Monolayers and Biomembranes . Wiley-Liss. New York (1995). Garrett, R. and Grisham C. Biochemistry , 2 nd ed. Saunders Colleges Publishing. New York (1999). 264.