Targeted drug delivery and their methods

Targeted drug delivery and their methods, Nano particles and Liposomes

1. TARGETED DRUG DELIVERY SYSTEM Manjit Kaur M. Pharmacy(2 nd Sem.) Department Of Pharmaceutics Sri Sai College Of Pharmacy 1

2. CONTENTS : • Introduction • Ideal characteristics • Advantages • Disadvantages • Carrier or markers • Strategies of drug targeting • Types of targeted drug delivery system 2

3. INTRODUCTION : ‘Targeted drug delivery system is a special form of drug delivery system where the medicament is selectively targeted or delivered only to its site of action or absorption and not to the non-target organs or tissues or cells.’ It is a method of delivering medication to a patient in a manner that increases the concentration of the medication in some parts of the body relative to others. 3

4. Targeted drug delivery seeks to concentrate the medication in the tissues of interest while reducing the relative concentration of the medication in the remaining tissues. This improves efficacy and reduce side effects. 4

5. OBJECTIVE To achieve a desired pharmacological response at a selected sites without undesirable interaction at other sites, there by the drug have a specific action with minimum side effects & better therapeutic index. Ex- In cancer chemotherapy and enzyme replacement therapy. 5

6. REASON FOR DRUG TARGETING In the treatment or prevention or diseases. Pharmaceutical drug instability in conventional dosage form is Solubility Biopharmaceutical low absorption, High membrane bounding, Biological instability, Pharmacokinetic/ pharmacodynamic short half life, Large volume of distribution, Low therapeutic index. 6

7. IDEAL CHARACTERISTICS It should be non-toxic, biocompatible, biodegradable, and physicochemical stable in-vivo and in-vitro. Restrict drug distribution to target cells or tissues or organs and should have uniform capillary distribution. Controllable and predicate rate of drug release. Drug release does not effect the drug action. 7

8. Therapeutic amount of drug release. Minimal drug leakage during transit. Carriers used must be bio-degradable or readily eliminated from the body without any problem and no carrier induced modulation of diseased state. The preparation of the delivery system should be easy or reasonably simple, reproductive and cost effective. 8

9. ADVANTAGES Drug administration protocols may be simplified. Toxicity is reduced by delivering a drug to its target site, there by reducing harmful systemic effects. Drug can be administered in a smaller dose to produce the desire effect. 9

10. Avoidance of hepatic first pass metabolism. Enhancement of the absorption of target molecules such as peptides and particulates. Dose is less compared to conventional drug delivery system. Selective targeting to infections cells that compare to normal cells. 10

11. DISADVANTAGES Rapid clearance of targeted systems. Immune reactions against intravenous administered carrier systems. Insufficient localization of targeted systems into tumour cells. Diffusion and redistribution of released drugs. Requires highly sophisticated technology for the formulation. Requires skill for manufacturing storage, administration. 11

12. Drug deposition at the target site may produce toxicity symptoms. Difficult to maintain stability of dosage form. e.g.: Resealed erythrocytes have to be stored at 4 C. Drug loading is usually low . e.g. As in micelles. Therefore it is difficult to predict /fix the dosage regimen. 12  

13. TYPES OF TARGETED DRUG DELIVERY SYSTEM Nano Tubes : They are hollow Cylinder made of carbon, atoms Which can be filled and sealed For potential drug delivery. Application: Cellular scale needle for attaching drug molecule to cancer cells. As an electrode in thermo cells. 13

14. Nano wires : The nanowire pinpoint damage from injury and stroke, localize the cause of seizures, and detect the presence of tumours and other brain abnormalities. Application : Technique has potential as a treatment for Parkinson's and similar diseases. 14

15. NANO-SHELLS : Nano-shells are hollow silica spheres covered with gold. Scientists can attach antibodies to their surfaces, enabling the shells to target certain shells such as cancer cells. Application : Technique has potential for targeting cancerous drug. 15

16. Quantum dots : Quantum dots are miniscule semiconductor particles that can serve as sign posts of certain types of cells or molecules in the body . Application : Technique has potential for targeting cancerous drug. 16

17. Nano pores : E ngineered into particles, they are holes that are so tiny that DNA molecules can pass through them one strand at a time, allowing for highly precise and efficient DNA sequencing. Application : P otential in genetic engineering and bio technology. 17

18. Gold Nano : P article scientist uses gold nanoparticle to develop ultrasensitive detection system for dna and protein markers associated with many forms of cancer, including breast prostrate cancer. Application : I n cancer treatment and genetic engineering. 18

19. Liposomes L iposomes are concentric bi-layered vesicles in which an aqueous core is entirely enclosed by a membranous lipid bilayer mainly composed of natural or synthetic phospholipids. T he size of a liposome ranges from some 20 nm up to several micrometres. 19

20. Liposomes : L iposomes are simple microscopic vesicles in which an aqueous volume is entirely composed by membrane of lipid molecule various amphiphilic molecules have been used to form liposomes. T he drug molecules can either be encapsulated in aqueous space or intercalated into the lipid bilayers. T he extent of location of drug will depend upon its physicochemical characteristics and composition of lipids. 20

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22. The lipid molecules are usually phospholipids- amphipathic moieties with a hydrophilic head group and two hydrophobic tails. On addition of excess water, such lipid moieties spontaneously originate to give the most thermodynamically stable conformation. In which polar head groups face outwards into the aqueous medium, and the lipid chains turns inwards to avoid the water phase, giving rise to double layer or bilayer lamellar structures. 22

23. BASIC LIPOSOME STRUCTURE 23

24. LAMELLA A lamella is a flat plate like structure that appears during the formation of liposomes. The phospholipids bilayer first exists as a lamella before getting converted into spheres. Several lamella of phospholipids bilayers are stacked one on top of the other during formation of liposomes to form a multilamellar structure. 24

25. Uni-lamellar vesicle Multi-lamellar vesicle 25

26. STRUCTURAL COMPONENTS OF LIPOSOMES T he main components of liposomes are :- Phospholipids Cholesterol 26

27. PHOSPHOLIPIDS Phospholipids are the major structural components of biological membranes such as the cell membrane. Phosphoglycerides Two types of phospholipids along with their hydrolysis ( products) Two types of phospholipids ( along with their hydrolysis products) Sphingolipids 27

28. PHOSPHATIDYLCHOLINE Most common phospholipids used is phosphatidylcholine (PC). Phosphatidylcholine is an amphipathic molecule in which exists:- – a hydrophilic polar head group, phosphocholine. – A glycerol bridge. – A pair of hydrophobic acyl hydrocarbon chains. 28

29. GENERALLY PHOSPHOLIPIDS ARE REPRESENTED AS FOLLOWS:- 29

30. CHOLESTEROL Cholesterol by itself does not form bilayer structure. Cholesterol act as fluidity buffer After intercalation with phospholipid molecules alter the freedom of motion of carbon molecules in the acyl chain Restricts the transformations of trans to gauche conformations Cholesterol incorporation increases the separation between choline head group & eliminates normal electrostatic & hydrogen bonding interactions 30

31. ADVANTAGES OF LIPOSOMES Provides selective passive targeting to tumour tissues. Increased efficacy and therapeutic index. Increased stability of encapsulated drug. Reduction in toxicity of the encapsulated agent. Site avoidance effect (avoids non-target tissues). Improved pharmacokinetic effects (reduced elimination  increased  circulation life times). Flexibility to couple with site specific ligands to achieve  active  targetting .  31

32. Disadvantages Physical/ chemical stability Very high production cost Drug leakage/ entrapment/ drug fusion Sterilization  Short  biological activity / t ½ Oxidation of bilayer phospholipids and low solubility Rate of release  and altered bio distribution Low therapeutic index and dose effectiveness Overcoming resistance Extensive clinical and laboratory research to a certain long  circulating liposomes Repeated iv administration problems 32

33. CLASSIFICATION OF LIPOSOMES MLV Multilamellar Large vesicles (>0.5 um ) OLV oligolamellar vesicles (>0.1-1.0 um) UV Unilamellar Vesicles (all size ranges) MVV Multivesicular vesicles ) 1.0 um (> MUV Medium Unilamellar Vesicles GUV Giant Unilamellar Vesicles um >1 SUV Small Unilamellar Vesicles nm 20-100 LUV Large Unilamellar Vesicles >100 nm Based on structural parameters 33

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35. PREPARATION OF LIPOSOMES Methods of liposome preparation Passive loading: Involves loading of the entrapped agents before or dur ing the manufacturing procedure. Active or remote loading: Certain types of compounds with ionisable groups and those with both manufacturing procedure lipid and water solubility can be introduced into the liposomes after the formation of the intact vesicles 35

36. Methods of liposome preparation Solvent dispersion methods  Ethanol injection  Ether injection  Double emulsion vesicles  Stable plurilamellar  Vesicles  Reverse phase evaporation vesicles Detergent removal methods Passive loading techniques  Detergent(Cholate, Alkyl glycoside, Triton X-100) removal from mixed micelles by  Dialysis  Column chromatography  Dilution  Reconstituted sendai virus enveloped vesicles Active loading techniques  Lipid film hydration by hand shaking non-hand shaking and freeze drying  Micro emulsification  Sonication  French pressure cell  Membrane extrusion  Dried reconstituted vesicles  Freeze thawed liposomes Mechanical dispersion methods 36

37. EVALUATION OF LIPOSOMES The liposomes prepared by various techniques are to be evaluated for their physical properties, has these influence the behaviour of liposomes in vivo. PHYSICAL PROPERTIES PARTICLE SIZE Both particle size and particle size distribution of liposomes influence their physical stability. These can be determined by the following method. Laser light scattering transmission electron microscopy 37

38. 2. SURFACE CHARGE The positive, negative or neutral charge on the surface of the liposomes is due to the composition of the head groups. The surface charge of liposomes governs the kinetic and extent of distribution in vivo, as well as interaction with the target cells. The method involved in the measurement of surface charge is based on free-flow electrophoresis of mlvs . 38

39. It utilizes a cellulose acetate plate dipped in sodium borate buffer of ph 8.8. About 5n moles of lipid samples are applied on to the plate, which is then subjected to electrophoresis at 4 ͦ c for 30 mins. The liposomes get bifurcated depending on their surface charge. This technique can be used for determining the heterogeneity of charges in the liposome suspension as well as to detect any impurities such as fatty acids. 39

40. 3. PERCENT DRUG ENCAPSULATED Quantity of drug entrapped in the liposomes helps to estimate the behaviour of the drug in biological system Liposomes are mixture of encapsulated and unencapsulated drug fractions The % of drug encapsulation is done by first separating the free drug fraction from encapsulated drug fraction The encapsulated fraction is then made to leak off the liposome into aqueous solution using suitable detergents The methods used to separate the free drug from the sample are: Mini column centrifugation method Protamine aggregated method 40

41. 5. DRUG RELEASE RATE The rate of drug release from the liposomes can be determined by in vivo assays which helps to predict the pharmacokinetics and bioavailability of the drug. However in vivo studies are found to be more complete. Liposome encapsulating the tracer [ᵌH] insulin are employed for ᵌ the study. This [ᵌH] insulin is preferred, as it is released only (ᵌH) in the ECF and undergoes rapid renal excretion of the face tracer coupled to the degradation rate constant or the tracer released from the liposomes. 41

42. APPLICATIONS Liposomes as drug or protein delivery vehicles. Liposome in antimicrobial, antifungal(lung therapeutics) and antiviral (anti HIV) therapy. In tumour therapy. In gene therapy. In immunology. Liposomes as artificial blood surrogates. Liposomes as radiopharmaceutical and radio diagnostic carriers. Liposomes in cosmetics and dermatology. 42

43. NANOPARTICLES INTRODUCTION : The prefix “ nano ” comes from the ancient greek vavoc through the latin nanus meaning very small. Nanotechnology defined as design characterization, production and applications of structures, devices and systems by controlling shape and size at nanometre scale. According to international system of units ( si ) nanotechnology is typically measured in nanometres scale of 1 billionth of a meter (1nm corresponding to 10-9 m) referred as the “tiny science”. 43

44. Nanoparticles ( nps ) are defined as particulate dispersions or solid particles drug carrier that may or may not be biodegradable. The drug is dissolved, entrapped, encapsulated or attached to a nanoparticle matrix. The term nanoparticle is a combined name for both nanospheres and nano capsules. Drug is confined to a cavity surrounded by a unique polymer membrane called nano capsules, while nanospheres are matrix systems in which the drug is physically and uniformly dispersed. Where conventional techniques reaches their limits, nanotechnology provides opportunities for the medical applications. 44

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46. ADVANTAGES OF NANO-PARTICLES Nanoparticles offers numerous advantage in drug delivery system. These advantage include, but are not limited: Nanoparticles have many significant advantage over conventional and traditional drug delivery system. 46

47. Nanoparticles are control and sustain release form at the site of localization, they alter organ distribution of drug compound. They enhance drug circulation in blood, bioavailability, therapeutic efficacy and reduce side effects. Nanoparticles can be administer by various routes including oral, nasal, parenteral, intra-ocular etc. In the tiny areas of body nanoparticles shows better drug delivery as compare to other dosage form and target to a particular cell type or receptor. 47

48. Nanoparticle enhance the aqueous solubility of poorly soluble drug, which improves bioavailability of drug. As a targeted drug carrier nanoparticles reduce drug toxicity and enhance efficient drug distribution. By using polymers drug release form nanoparticles can be modified which makes polymeric nanoparticle an ideal drug delivery system for cancer therapy, vaccines, contraceptives and antibiotics. Useful to diagnose various diseases Enhanced stability of ingredients Prolonged shelf life Used in dental surgery also as filling the tiny holes in teeth. Change the method of drug delivery to improve customer acceptance or reduce manufacturing costs. 48

49. S.NO TYPES OF NANOPARTICLE MATERIALS UED APPLICATION 1 NANOSUSPENSIONS AND NANOCRYSTALS Drug powder is disperse d in surfactant solution Stable system for controlled delivery of poorly soluble drug 2 Solid lipid Nanoparticles Melted lipid dispersed in Aqueous surfactant Least toxic and more stable Colloidal carrier systems as alternative materials To polymers 3 Polymeric nanoparticles Biodegradable polymer Controlled and targeted drug delivery 4 Polymeric micelles Amphiphilic block co polymers Controlled and systemic Delivery of water insoluble Drugs 5 Magnetic Nanoparticles Magnetite Fe2O3,Meghe Mite coated with dextran Drug targeting diagnostics to in medicine 6 Carbon Nanotubes Metals ,semiconductors Gene and DNA delivery 49

50. POLYMERS USED IN PREPRATION 50

51. NATURAL HYDROPHILIC POLYMER PROTEINS POLYSACCHARIDES Gelatin Alginates Albumin Dextran Lectins Chitosan Legumin Agarose Vicilin Pullulan 51

52. SYNTHETIC HYDROPHOBIC POLYMER PRE-POLYMERIZED POLYMERIZED IN PROCESS Poly (e-caprolactone) (PECL) Poly(isobutylcyanoacrylates) (PICA) Poly(lactic acid) (PLA) Poly(butylcyanoacrylates) (PBCA) Poly ( lactide -co- glycolide ) (PLGA) Polyhexylcyanoacrylate (PHCA) Polystyrene Poly methyl (methacrylate)(PMMA) 52

53. METHODS OF PREPARATION OF NANOPARTICLES BY DISPERSION OF PREFORMED POLYMER 53

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55. PREPARATION TECHNIQUES Solvent Evaporation: Solvent evaporation method first developed for preparation of nanoparticles. In this method firstly nano -emulsion formulation prepared. Polymer dissolved in organic solvent (dichloromethane, chloroform or ethyl acetate). Drug is dispersed in this solution. Then this mixtures emulsified in an aqueous phase containing surfactant (polysorbates, poloxamers sodium dodecyl sulphates polyvinyl alcohol, gelatine) make an oil in water emulsion by using mechanical stirring, sonication, or micro fluidization (high-pressure homogenization through narrow channels). After formation of emulsion the organic solvent evaporate by increased the temperature and reduced pressure with continuous stirring. 55

56. EMULSIONS - DIFFUSION METHOD This method patent by leroux et al it is modified form of salting out method. Polymer dissolved in water-miscible solvent (propylene carbonate, benzyl alcohol), this solution saturated with water. Polymer-water saturated solvent phase is emulsified in an aqueous solution containing stabilizer. Then solvent removed by evaporation or filtration. Advantages of this method are high encapsulation efficiencies (generally 70%), no need for homogenization, high batch-to-batch reproducibility, ease of scaleup, simplicity, and narrow size distribution. Some disadvantage of this method is reported high volumes of water to be eliminated from the suspension and the leakage of water-soluble drug into the saturated aqueous external phase during emulsification, reducing encapsulation efficiency. 56

57. NANO-PRECIPITATION METHOD This is another method which is widely used for nanoparticle preparation which is also called solvent displacement method. In this method precipitation of polymer and drug obtained from organic solvent and the organic solvent diffused in to the aqueous medium with or without presence of surfactant. Firstly drug was dissolved in water, and then cosolvent (acetone used for make inner phase more homogeneous) was added into this solution. 57

58. Then another solution of polymer (ethyl cellulose, eudragit) and propylene glycol with chloroform prepared, and this solution was dispersed to the drug solution. This dispersion was slowly added to 10 ml of 70% aqueous ethanol solution. After 5 minutes of mixing, the organic solvents were removed by evaporation at 35° under normal pressure, nanoparticles were separated by using cooling centrifuge (10000 rpm for 20 min), supernatant were removed and nanoparticles washed with water and dried at room temperature in a desiccator 58

59. EVALUATION PARAMETER OF NANOPARTICLES YIELD OF NANOPARTICLES:- Percentage yield = amount of particle (100) Amount of drug+ polymer DRUG CONTENT/SURFACE ENTRAPMENT/ DRUG ENTRAPMENT:- Percentage drug entrapment = W - w (100) W PARTICLE SIZE:- Particle size and its distribution is important characteristics in nanoparticles as they plays major role in distribution, pharmacological activity, toxicity and targeting to specific sites. Advanced methods to determine the particle size of nanoparticles is by photon-correlation spectroscopy or dynamic light scattering, scanning electron microscopy 59

60. PARTICLE SHAPE:- Particle shape of the nano suspensions is determined by scanning electron microscopy (SEM). In order to form the solid particles these nano suspensions were subjected to lyophilisation. ZETA POTENTIAL:- Zeta potential is the potential difference existing between the surface of a solid particle immersed in a conducting liquid and the bulk of the liquid. The surface charge of the nanoparticles is usually measured by zeta potential. DIFFERENTIAL SCANNING CALORIMERTY (DSC):- It is used to Determine the nature of crystallinity within nanoparticles through the measurement of glass and melting point tempertures and their associated enthalpies. 60

61. ATOMIC FORCE MICROSCOPY (AFM):- It offers a ultra-high resolution in particle size measurement and is based on a physical scanning of sample at submicron level using a probe tip of atomic scale. AFM provides the most accurate description of size and size distribution and requires non mathematical treatment. 61

62. DRUG RELEASE AND RELEASE KINETIC The release of drug from the particulate system depends upon three different mechanism: Release from the surface of particles. Diffusion through the swollen rubbery matrix. Release due to erosion. 62

63. IN VITRO DRUG RELEASE STUDIES DISSOLUTION:- solution from the 63

64. STABILITY OF NANOPARTICLES :- • Nanoparticles detemination • Storing optimized formulation degree Celsius 4 + 1 degree Celsius & 30 dergree celsius + 2 dergree celsius • Sample analyzed • Stability chamber for 90 days ,1,2 & 3 month time period • Any changes in physical appearance Their drug content, drug release rate 64

65. APPLICATIONS Used in targeted drug delivery to brain therapy. Used in targeting of nanoparticles to epithelial cells in the gi tract using ligands. Nanoparticles for gene delivery. Used in bio detection of pathogens. Used in detection of stem cell therapy, cancer therapy. USED IN BIO 65

66. COMMERICAL PRODUCTS OF NANOPRATICLES COMPANY TRADE NAME COMPOSITION INDICATION ROUTES Astra Zeneca Pharma Diprivan Propofol liposomes /lipid Anesthetic IV Teva Pharma Copaxone Copolymeric mixture of L - glutamic acid, L - alanine , L - tyrosine & L - lysine Relapsing remitting multiple sclerosis subcutaneous Bio Sante Elestrin Estradiol gel (0.06%) Moderate to severe hot flashes in menopausal women Transdermal Abraxis Bioscience Abraxane Paclitaxel ( Taxol ) bound albumin nanoparticles Various cancers IV 66

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