Liposomes. Mahmoud R. Jaafari, PhD Prof. of Pharmaceutics and Pharmaceutical Nanotechnology

Transcription

1 Liposomes Mahmoud R. Jaafari, PhD Prof. of Pharmaceutics and Pharmaceutical Nanotechnology

2 Course Outline Definition of liposomes Classification of liposomes Structure of liposomes Preparation of liposomes Purification of liposomes Characterization of liposomes Liposome-cell interaction Liposomes as drug delivery systems Targeted Drug Delivery Liposomes as a vaccine adjuvant

3 References Liposomes, Second Edition, Vladimir P. Torchilin and Volkmar Weissig, Oxford University Press, 2003 Liposomes: a practical approach, R.R.C. New, Oxford University Press, 1997

4 Definition:Liposomes are spherical microscopic vesicles consisting phospholipids bilayers which enclose aqueous compartments

5 Described by Bangham in 1965 Study of membranes Spherical vesicles with a phospholipid bilayer

6 Small unilamellar vesicles (SUV), 25 to 100 nm in size that consist of a single bilayer Large unilamellar vesicle (LUV), 100 to 500 nm in size that consist of a single bilayer Multilamellar vesicle (MLV), 200 nm to several microns,that consist of two or more concentric bilayer Classification

7 Structure of Liposomes: Phospholipids

8 Structure of Liposomes: Phospholipids Polar Head Groups Three carbon glycerol

9 Structure of Liposomes: Phospholipids

10 Structure of Liposomes: Phospholipids

11 Structure of Liposomes: Phospholipids

12 The Lipid Bilayer

13 The Lipid Bilayer

14 Structure of Liposomes: Phospholipids

15 Phase Transition Temperature Tm: Gel-Like Solid and Liquid Crystal

16 Phase Transition Temperature Tm: Differential Scanning Calorimetry (DSC)

17 Phase Transition Temperature Tm

18 Phase Transition Temperature Tm

19 Cholesterol

20 Cholesterol

21 DSC of Chol/DSPC MHC of SChcPC and DSPC Cp (Kcal/K/mol) DSPC 5% Chol 10% Chol 20% Chol 30% Chol 35% Chol 40% Chol 50% Chol 60% Chol SChcPC 2 Endo Temperature (ºC)

22 Non Structural Components

23 Membrane permeability

24 Methods of Preparation of Liposomes Mechanical Dispersion Solvent Dispersion Detergent Solubilization

25 Mechanical Dispersion: Solvent evaporation method (hand shaken multilamellar vesicles), Film Method

26 Processing of lipids hydrated (MLVs) by Sonicated vesicles physical means

27 Processing of lipids hydrated (MLVs) by physical means EmulsiFlex High Pressure Homogenizar

28 Processing of lipids hydrated (MLVs) by physical means: EmulsiFlex High Pressure Homogenizar

29 Processing of lipids hydrated (MLVs) by physical means Membrane Extrusion Liposomes

30 Lipex Extruders

31 Processing of lipids hydrated (MLVs) by physical means Membrane Extrusion Liposomes

32 Ethanol injection Solvent Dispersion

33 Detergent Solubilization Method

34

35 Detergent Solubilization Method

36 Detergent Solubilization Method

37 Membrane proteins can be solubillized and purified in detergents

38 Purification of Liposomes

39 Purification of Liposomes Gel Filtration Column Chromatography

40 Purification of Liposomes Gel Filtration Column Chromatography

41 Dialysis Purification of Liposomes

42 Purification of Liposomes Centrifugation

43 Stability of Liposomes Chemical degradation Physical degradation Prevention of chemical degradation Prevention of physical degradation

44 Preparation of Sterile Liposomes

45 Lyophilization of liposomes

46 Liposome Characterization Assay of encapsulated drug Determination of Percent Capture Indirect Direct Determination of Percentage Release Size distribution: Light microscopy, TEM, Dynamic light scattering Zeta potential

47 Liposome characterization Lamellarity Phospholipid assay Phosphate assay Cholesterol assay Tm by DSC Stability: Drug, lipid and liposome

48 Liposomes in drug delivery Biodegradable and biocompatible Protect the encapsulated drug from metabolic degradation Increase the half-life of drug Could be used as sustained release vehicles It is possible to target them to selected tissues or cell and reduce the systemic toxicity of drugs

49 Types of liposomes

50 Stealth or PEG-Liposomes

51 Phagocytosis with the cells of reticuloendothelial system (RES)

52 PEG extends 5 nm from Lipid Bilayer Interface Tightly associates with water molecules Decreases liposome elimination

53 PEG2000-DSPE

54 Barriers for intravenous liposomal drug delivery Cells of reticuloendothelial system (RES) Endothelial barrier between the lumen of the vasculature and extravascular compartment Basal lamina (extracellular matrix) Cellular barrier

55 Barriers for intravenous liposomal drug delivery

56 Liposome Biodistribution: I.V. Administration

57 Liposome-cell interaction

58 Liposome-cell interaction

59 Other neutral phospholipids: Phosphatidyl ethanolamine

60 Other neutral phospholipids: Phosphatidyl ethanolamine

61 Doxil: Liposomal Doxrubicin for IV Infusion Doxrubicin 20 mg MPEG-DSPE 31.9 mg Fully Hydrogenated Soy PC 95.8 mg Cholesterol 31.9 mg Histidine as buffer Sucrose D. W. for injection q.s. to 10 ml

62 Stealth Liposomes 100 nm Poly(ethylene glycol) Lipid bilayer Doxorubicin

63 Intraliposomal remote loading of doxorubicin by creating ammonium sulfate gradient between the intraliposomal aqueous phase and the external medium Permeability coefficients

64 Enhanced Penetration and Retention (EPR Effect) 64 Matsamura Y., Maeda H. Cancer Res., 1986, 46,

65 Extravasation and Release of Liposomal Drug Cargo in Tumor Interstitial Fluid Tumor compartment: Interstitial fluid Tumor Cells 5 Vascular space

66 Doxil Vs free doxorubicin (PK)

67 Doxil vs. Doxorubicin Limited volume of distribution(2.5 to 3 L/m2 vs L/m2) Slower clearance from the circulation(0.04 L/h/m2 vs 27to 59 L/H/M2) Prolonged half life (55 hrs vs hrs) Three fold greater AUC Cardiac function: Major reduction of cardiotoxicity as compared to free doxorubicin

68 Doxil Treatment of ovarian cancer where the disease has progressed or recurred after platinum-based chemotherapy Treatment of metastatic breast cancer Treatment of relapsed/refractory multiple myeloma in combination with Bortezomib (Velcade) Treatment of AIDS-related Kaposi s sarcoma Clinical Trials: liver cancer, pancreatic cancer and bladder cancer

69 DaunoXome: Daunorubicin citrate DSPC (10) 704 mg Cholesterol (5) 168 mg Daunorubicin (1) 50 mg Sucrose 2.125mg Glycine 94 mg Calcium Chloride Dihydrate 7 mg Citrate buffer Mean Diameter 45 nm Vd: 6.4 (1006) T1/2: 4.41 (0.77) Treatment of AIDS-related Kaposi s sarcoma liposome injection

70 DaunoXome: Daunorubicin citrate liposome injection

71 Depocyt: Cytarabin liposomal injection, 50 mg per vial Each ml contain: Cytarabine 10 mg DOPC 5.7 mg DPPG 1.0 mg Cholesterol 4.1 mg Triolein 1.2 mg Sodium Chloride 0.9% Cytarabine is freely soluble in water No preservative, used directly in CSF for Lymphomatous meningitis, sustained release, 50 mg every two week. Lymphomatous meningitis can be controlled with cytarabine, but because of the drug's short half-life, a spinal injection is required twice per week, whereas DepoCyt is dosed once every two weeks. DepoCyt gradually releases cytarabine into the cerebral spinal fluid resulting in a significantly extended half-life, prolonged exposure to the therapy, and a more uniform distribution.

72 Depocyt: Cytarabin liposomal injection, 50 mg per vial

73 Amphotericin B (AmB) AmB a natural fermentation product from Streptomyces nodous Consist of a large, amphipathic macrolide lactone ring that presents seven conjugated double bonds on one side and seven polar hydroxyl groups on the other side

74 Amphotericin B Insoluble in water, slightly soluble in methanol (around 0.5 mg/ml), soluble in DMSO (30-40 mg/ml). Broad-spectrum antifungal activity Antifungal of choice for the treatment of lifethreatening infections, despite sever acute and chronic toxicity, including dose-limiting nephrotoxicity LD50 in mice, i.v. 2-4 mg/kg, i.p. 88 mg/kg

75 Amphotericin B AmB acts by binding to the sterol component of a cell membrane, forms pores or channels in sterolcontaining membranes, which changes permeability of cell membrane and causes leakage of protones, monovalent cations and other cell constituents leading to cell death. The affinity of AmB for ergosterol (the primary sterol of fungal membrane) is almost 10-fold higher than cholesterol (the primary sterol of mammalian membrane)

76 Amphotericin B formulations in the market Fungizone: a mixed micelle with deoxycholate as the surfactant (d- AmB) AmB colloidal dispersion (Amphotec): a 1:1 molar ratio of AmB with the sterol cholestryl sulfate, a disk-like particles of diameter>100nm and thickness<10nm AmB lipid complex (Abelcet): a lipid complex that is an association of DMPC, DMPG and AmB in a 10:7:3 molar ratio, a micron sized ribbon-like structures AmBisome

77 AmBisome: Liposomal Amphotericin B for injection Amphotericin B 50 mg Hydrogenated Soy PC 213 mg Cholesterol 52 mg DSPG 84 mg Alpha tocopherol 0.64 mg Sucrose 900 mg Disodium Succinate Hexahydrate 27 mg Reconstitution with 12 ml of sterile water for injection SUVs intercalated with Amphotericin B with less than 100 nm in size HSPC/Chol/DSPG/AmB molar ratio, 5:2.5:2:1 Therapeutic index: AmBisome>>Amphotec=Abelcet>d-AmB Methods of preparation: SEM to prepare MLVs, then the resulted MLVs are microemulsified to get the SUVs intercalated with Amphotericin B with less than 100 nm in size

78 AmBisome: Liposomal Amphotericin B for injection AmBisome, a liposomal formulation of amphotericin B. The liposome is composed of high transition temperature phospholipids and cholesterol, designed to incorporate amphotericin B securely into the liposomal bilayer. AmBisome can bind to fungal cell walls, where the liposome is disrupted. The amphotericin B, after being released from the liposomes, is thought to transfer through the cell wall and bind to ergosterol in the fungal cell membrane. This mechanism of action of AmBisome results in its potent in vitro fungicidal activity while the integrity of the liposome is maintained in the presence of mammalian cells, for which it has minimal toxicity. In animal models, AmBisome is effective in treating both intracellular (leishmaniasis and histoplasmosis) and extracellular (candidosis and aspergillosis) systemic infections.

79 AmBisome: Liposomal Amphotericin B for injection Because of its low toxicity at the organ level, intravenous AmBisome can be safely delivered at markedly high doses of amphotericin B (1 30 mg/kg) for the treatment of systemic fungal infections. AmBisome has a circulating half-life of 5 24 h in animals, and in animal models appears to localize at sites of infection in the brain (cryptococcosis, aspergillosis, coccidioidomycosis), lungs (blastomycosis, paracoccidioidomycosis, aspergillosis) and kidneys (candidosis), delivering amphotericin B that remains bioavailable in tissues for several weeks following treatment.

80 Smilosome Thank you for your attention