measures of central tendency biostastistics

it is about measurement of central tendency

1. Nanoparticles

2. CONTENTS INTRODUCTION POLYMERS USED PREPARATION TECHNIQUES NOVEL NANOPARTICULATE SYSTEMS DRUG LOADING AND IN VITRO RELEASE PROCESS CHARACTERIZATION IN VIVO FATE AND BIODISTRIBUTION THERAPEUTIC APPLICATIONS

3. INTRODUCTION Nanoparticles are sub- nanosized colloidal structures composed of synthetic or semi-synthetic polymers Also defined as particulate dispersions or solid particles with a size in the range of 10-1000nm The drug is dissolved, entrapped, encapsulated or attached to a nanoparticle matrix

4. Major goals To control particle size, surface properties and release of pharmacologically active agents in order to achieve the site-specific action of the drug at the therapeutically optimal rate and dose regimen

5. Advantages of nanoparticles as DDS Particle size and surface characteristics of nanoparticles can be easily manipulated to achieve both passive and active drug targeting. They control and sustain the release of the drug during the transportation and at the site of localization, altering organ distribution of the drug and subsequent clearance of the drug so as to achieve increase in drug therapeutic efficacy and reduction in side effects.

6. ADVANTAGES ( cont …) Controlled release and particle degradation characteristics can be readily modulated by the choice of matrix constituents. Drug loading is relatively high and drugs can be incorporated into the systems without any chemical reaction; this is an important factor for preserving the drug activity.

7. ADVANTAGES ( cont …) Site-specific targeting can be achieved by attaching targeting ligands to surface of particles or use of magnetic guidance. The system can be used for various routes of administration including oral, nasal, parenteral , intra-ocular etc.

8. solid core spherical particulates in which drug is embedded within the matrix or adsorbed on to surface nanometer-sized single crystals, or single-domain ultrafine particles Types of Nanoparticles vesicular system in which drug is encapsulated within the central volume surrounded by an embryonic continuous polymeric sheath Depending on the method of preparation :- NANOSPHERES : NANOCRYSTALS : NANOCAPSULES :

9. NATURAL HYDROPHILIC POLYMERS SYNTHETIC HYDROPHOBIC POLYMERS polymers Divided in to two major classes :

10. Conveniently classified as : Natural hydrophilic polymers PROTEINS POLYSACCHARIDES Gelatin Albumin Lectins Legumin Vicilin Alginate Dextran Chitosan Agarose Pullulan

11. disadvantages Batch-to-batch variation Conditional biodegradability Low hydrophobicity Parenteral administration of polymeric nanoparticles gets compromised mainly due to antigenicity Alginate based delivery systems for oral and ophthalmic preparations have been approved

12. Synthetic hydrophobic polymers PRE-POLYMERIZED (1 ST GROUP) POLYMERIZED IN PROCESS (2 ND GROUP) Poly ( ε - caprolactone ) (PECL) Poly lactic acid (PLA) Poly ( lactide -co- glycolide ) (PLGA) Polystyrene Poly ( isobutylcyanoacrylates ) (PICA) Poly ( butylcyanoacrylates ) (PBCA) Poly hexylcyanoacrylate (PHCA) Poly methyl ( methacrylate ) (PMMA) Copolymer of amino alkyl methacrylate methyl methacrylate

13. Size of nanoparticles require d Inherent properties of the drug, e.g., aqueous solubility and stability Surface characteristics such as charge and permeability Degree of biodegradability, biocompatability and toxicity Drug release profile required Antigenicity of the final product Selection criteria of polymers

14. Preparation techniques of nanoparticles Selection criteria : Physicochemical characteristics of polymer Properties of drug to be loaded

15. Types of systems obtained A matrix type system consisting of an entanglement of oligopolymer or polymer units ( nanoparticles / nanospheres ) A reservoir type of system comprised of an oily core surrounded by an embryonic polymeric shell ( nanocapsules )

16. AMPHIPHILIC MACROMOLECULE CROSS LINKING POLYMER PRECIPITATION METHODS METHODOLOGIES POLYMERIZATION BASED METHODS

17. M ethodologies (cont…) AMPHIPHILIC MACROMOLECULE CROSS LINKING Heat cross linking Chemical cross linking

18. Methodologies (cont…) POLYMERIZATION BASED METHODS Emulsion ( micellar ) polymerization Dispersion polymerization Interfacial condensation polymerization Interfacial complexation

19. Methodologies ( cont. .) POLYMER PRECIPITATION METHODS Solvent extraction / evaporation Solvent displacement ( Nanoprecipitation ) Salting out

20. Amphiphilic Macromolecule Cross Linking Prepared from proteins and polysaccharides which have affinity for aqueous and lipid solvents Technique involves : Aggregation of amphiphiles Further stabilization either by heat denaturation or chemical cross linking

21. Emulsification method Set forth by Scheffel et al. (1972) to prepare albumin nanoparticles Aqueous solution from albumin is turned into an emulsion at room temperature and in plant oil (cotton seed oil) Then by a mechanical homogenizer with high speed, we can obtain a homogeneous emulsion The above emulsion will be added to a high volume of pre-heated oil (over 120°C) drop by drop. This process will result a rapid evaporation of existed water and will also cause formation of nanoparticles .

22. Particles are finally washed with an organic solvent and collected by centrifugation The crucial factors which govern the size and shape of the nanoparticles are Emulsification energy Temperature Disadvantage : not applicable for temperature sensitive drugs

23. As an alternative, a chemical cross linking agent, usually gluteraldehyde is incorporated in to the system at a 3% v/v level Disadvantages : Removal of residual cross linking agent makes the method cumbersome Variable size of nanoparticles

24. Emulsion chemical dehydration For producing BSA nanoparticles with a narrow size distribution ( Bhargava & Aindo , 1992) Hydroxypropyl cellulose solution in chloroform was used as the continuous phase of emulsion and 2,2-dimethyl propane was used as the chemical dehydrating agent to translate the internal aqueous phase into a solid particulate system

25. Protein dissolution Protein aggregation Phase separation in aqueous medium ( Desolvation ) Protein deaggregation Method proceeds in 3 steps :

26. Work done by Marty et al., 1978 The foundation of this method was using a desolvation factor such as natural salts or alcohol which should be added to protein solution slowly Protein third structure will changed Nanoparticles will result by this polymerization clump crosslinkage with a chemical factor that is glutaraldehyde In order to stop such kind of accumulation and creating ideal nanodispersion , we must use a resolvating agent

27. Counter ion induced aggregation / Ionic gelation method Aggregation of dispersed phase initiated by adding some appropriate counter ions Calvo and co-workers developed a method for preparing hydrophilic chitosan nanoparticles by ionic gelation Method involves a mixture of two aqueous phases, of which one is the polymer chitosan , and the other is a polyanion sodium tripolyphosphate

28. Positively charged amino group of chitosan interacts with negatively charged tripolyphosphate to form coacervates with a size in the range of nanometer Coacervates are formed as a result of electrostatic interaction between two aqueous phases Ionic gelation involves the material undergoing transition from liquid to gel due to ionic interaction conditions at room temperature

29. Polymerization Based Methods Two different approaches are adopted : The monomer to be polymerized is emulsified in a non- solvent phase (emulsion polymerization) The monomer is dissolved in a solvent that is non-solvent for the resulting polymer (dispersion polymerization )

30. Emulsion polymerization It can be conventional or inverse , depending upon the nature of the continuous phase in the emulsion In the former case, continuous phase is aqueous (O/W emulsion) In the latter case, it is organic (W/ Oemulsion )

31. Micellar nucleation and polymerization Homogenous nucleation and polymerization Two mechanisms were proposed :

32. Micellar nucleation and polymerization Swollen monomer micelles act as the site of nucleation and polymerization Monomer is emulsified in the non-solvent phase with the help of surfactant This leads to the formation of monomer-swollen micelles and stabilized monomer droplets

33. Polymerization reaction proceeds through nucleation and propagation stage in the presence of a chemical/physical initiator The energy provided by the initiator creates free reactive monomers in the continuous phase, which then collide with surrounding unreactive monomers and initiate the polymerization reaction Monomer molecules reach the micelles by diffusion from the monomer droplets, thus allowing the polymerization to progress within the micelles

34. Homogenous nucleation and polymerization Applied when the monomer is sufficiently soluble in the continuous phase Nucleation and polymerization can directly occur leading to the formation of primary chains called oligomers When the oligomers have reached a certain length, they precipitate and form primary particles, which are stabilized by surfactant

35. Depending on the bulk condition and system stability, the end product nanospheres are formed either by additional monomer input or by fusion of the primary particles

36. Example : Emulsion polymerization is a very popular approach used to synthesize polymer colloids with a matrix structure Preparation of biodegradable nanoparticles for the delivery of drugs with various physico-chenlical properties ( Couvreur et al. [1979]) polymerization of polyalkylcyanoacrylates

37. Dispersion Polymerization Here, the monomer is dissolved in an aqueous medium which acts as a precipitant for subsequently formed polymer Nucleation is directly induced in the aqueous monomer solution and the presence of stabilizer or surfactant is not necessary for the formation of stable nanospheres

38. Used to prepare biodegradable polyacrylamide and PMMA nanoparticles ( Kreuter and Speiser , 1976)

39. Interfacial Polymerization Developed to prepare nanocapsules consisting of a liquid core surrounded by a thin polymer envelope [Al Khoury-Fallouh et al., 1986] The reactions are performed either in W/O or in O/W emulsion systems, or in microemulsions , leading to the production of water- or oil-containing nanocapsules , respectively Oil-containing nanocapsules are obtained by the polymerization of alkylcyanoacrylates at the oil/water interface of a very fine O/W emulsion [Al Khoury-Fallouh et al., 1986]

40. Water containing nanocapsules may be obtained by the interfacial polymerization of alkylcyanoacrylate in W/O microemulsions In these systems, water-swollen micelles of surfactants of small and uniform size are dispersed in an organic phase The monomer is added to the microemulsion and polymerizes at the surface of the micelles The polymer forms locally at the water-oil interface and precipitates to produce the nanocapsule shell [ Gasco and Trotta , 1986]

41. The resultant mixture turns milky due to the formation of nanocapsules Solvent is subsequently removed under vacuum Size = 30 – 300nm Surfactant in small quantity can be added Used for encapsulation of proteins, enzymes, antibodies

42. Nanocapsules prepared by interfacial reaction of two monomers Method involves the formation of W/O microemulsion in which the aqueous phase contains enzymes/proteins and water soluble monomer Second monomer, which is hydrophobic, is added to bulk dispersion phase This initiates condensation reaction at the interface

43. Interfacial Complexation Aqueous polyelectrolyte solution is carefully dissolved in reverse micelles in an apolar bulk phase with the help of an appropriate surfactant Subsequently, competing polyelectrolyte is added to the bulk, which allows a layer of insoluble polyelectrolyte complex to coacervate at the interface

44. Polymer Precipitation Methods In these methods, the hydrophobic polymer and/or a hydrophobic drug is dissolved in a particular organic solvent followed by its dispersion in a continuous aqueous phase, in which the polymer is insoluble

45. Polymer precipitation is brought about by : Increasing the solubility of the organic solvent in the external medium by adding an alcohol By incorporating additional amount of water in to the ultraemulsion By evaporation of the organic solvent at room temperature or at accelerated temperatures or by using vacuum Using an organic solvent that is completely soluble in the continuous aqueous phase ( nanoprecipitation )

46. Solvent Evaporation Method Polymer is dissolved in an organic solvent (dichloromethane, chloroform or ethyl acetate) which is also used as the solvent for dissolving the drug This mixture is then emulsified in an aqueous solution containing a surfactant or emulsifying agent to form an O/W emulsion After the formation of stable emulsion, the organic solvent is evaporated either by reducing the pressure or by continuous stirring

47. Particle size was found to be influenced by type and concentrations of stabilizer homogenizer speed polymer concentration to produce small particle size, often a high-speed homogenization or ultra sonication may be employed

48. Example : Preparation of PLGA nanospheres ( Gumy et al., 1981) Polymer is solubilized in chloroform and dispersed in a gelatin solution by sonication to yield O/W emulsion Solvent is removed by evaporation

49. Solvent diffusion method Also called spontaneous emulsification method Modified version of solvent evaporation method Water miscible solvent along with a small amount of the water immiscible organic solvent is used as an oil phase

50. Due to the spontaneous diffusion of solvents, an interfacial turbulence is created between the two phases, leading to the formation of small particles As the concentration of water miscible solvent increases, a decrease in the size of particle can be achieved

51. Double Emulsion Solvent Evaporation Method Preparation of BSA loaded PLGA nanoparticles (Song et al., 1997) BSA and PLGA are dissolved separately in aqueous and organic phases, respectively Subjected to ultrasonication to yield W/O emulsion This is further added to a PVA aqueous solution to yield W/O/W double emulsion Organic solvent is allowed to evaporate

52. Solvent Displacement or Nanoprecipitation It involves the use of an organic phase, which is completely soluble in the external aqueous phase A solution of polymer, drug and lipophilic stabilizer (surfactant) in a semi-polar solvent miscible with water is injected into an aqueous solution (being a non-solvent for drug and polymer) containing another stabilizer under moderate stirring

53. Organic solvent diffuses to the external phase inducing immediate polymer precipitation due to the complete miscibility of both the phases The organic solvent is removed under reduced pressure [Kumar et at., 2004] Useful for drugs which are slightly soluble in water Example : Preparation of ovalbumin loaded dextran nanospheres (Schroder and Stahl, 1984)

54. Salting Out A solution of polymer and drug in a water miscible solvent is prepared It is added to an aqueous solution containing a salting -out agent and a stabilizer Under stirring, small droplets can be obtained The salting-out agent reduces the solubility of the drug and polymer in water

55. Dilution of the resulting O/W emulsion with water forces diffusion of organic solvent into the aqueous phase The remaining polymer together with the drug produces particles in the nano-size range [ Allemann et al., 1993 b] The resulting dispersion often requires a purification step to remove the salting-out agent [Ibrahim et al., 1992; Allemann et al., 1992] Used for drugs and polymers that are soluble in polar solvents (acetone or ethanol)

56. POLYMER USED TECHNIQUE CANDIDATE DRUG Hydrophilic Albumin, gelatin Alginate, Chitosan Dextran Hydrophobic Polyalkylcyanoacrylates Polyesters PLA, PLGA, PECL Heat denaturation & cross-linking in W/O emulsion Desolvation & cross-linking in aqueous medium Cross-linking in aqueous medium Polymer precipitation in organic solvent Emulsion polymerization Interfacial O/W polymerization Solvent extraction – evaporation Solvent displacement Salting out Hydrophilic Hydrophilic & Protein affinity Hydrophilic & Protein affinity Hydrophilic Hydrophilic Hydrophobic Hydrophilic & Hydrophobic Soluble in polar solvent

57. SUPER CRITICAL FLUID TECHNOLOGY Supercritical fluid can be defined as a solvent at a temperature above its critical temperature, at which the fluid remains a single phase regardless of pressure Supercritical CO2 (SC CO2) is the most widely used Most common techniques involve : supercritical anti-solvent (SAS) rapid expansion of critical solution (RESS)

58. Nanocapsules

59. Particle Replication in Non-Wetting Templates (PRINT)

60. ABRAXANE First polymeric nanoparticle based product From American Pharmaceutical Partners, Inc . , and American Bioscience, Inc. (ABI) Consists of albumin-bound paclitaxel nanoparticles Used to treat breast cancer Free of toxic solvents like cremophor -EL , which is used until now to solubilize paclitaxel in order to administer it intravenously to the patient

61. Prepared by high pressure homogenisation of paclitaxel in presence of serum albumin resulting in nanoparticulate colloidal suspension Size of nanoparticles = 130nm Lyophilized powder reconstituted for iv administration Dose : single use 100mg vial Shorter infusion time (30 min)

62. NOVEL NANOPARTICULATE SYSTEMS

63. SOLID LIPID NANOPARTICLES (SLN) Sub-micron colloidal carriers (50-1000nm) consist of a solid hydrophobic core having a monolayer of  phospholipids coating The solid core contains drug dissolved or dispersed in the solid high melting fat matrix The hydrophobic chains of phospholipids are embedded in the fat matrix

64. ADVANTAGES OF SLN Provide site-specific drug delivery due to small size and narrow size distribution Controlled release of active drug over a long period can be achieved Protection of incorporated drug against chemical degradation No toxic metabolites are produced

65. ADVANTAGES (cont…) Avoidance of organic solvents Relatively cheaper and stable Ease of industrial scale production Incorporation of drug can reduce distinct side effects Surface modification can easily be accomplished

66. COPOLYMERIZED PEPTIDE NANOPARTICLES (CPP) Modification of polymer-based system Used for delivery of therapeutic peptides as drug polymer conjugates Drug moiety is covalently bound to the carrier instead of being physically entrapped Particle size = 100nm

67. HYDROGEL NANOPARTICLES Hydrogels are 3-D hydrophilic polymer networks that swell in water or biological fluids without dissolving as a result of chemical or physical crosslinks Can be used to target the release of a drug or protein to a specific area of the body and simultaneously control the release kinetics due to their three-dimensional structure

68. Belong to the group of the swelling-controlled drug delivery systems When the polymer network comes in contact with aqueous solutions, the thermodynamic compatibility of the polymer chains and water causes the polymer to swell The drug trapped inside the hydrogel dissolves with the imbibed water and starts diffusing out of the network

69. NANOCRYSTALS Aggregates of around hundreds or thousands of molecules that combine in a crystalline form Composed of pure drug with only a thin coating comprised of surfactant or combination of surfactants Production technique of nanocrystals NANONISATION The size of nanocrystals allows for safe and effective passage through capillaries Example : RAPAMUNE ( sirolimus )

70. NANOSUSPENSION To produce nanosuspensions , the drug powder is dispersed in an aqueous surfactant solution by high speed stirring The obtained macrosuspension is then homogenized to nanosize by wet milling, high-pressure homogenization, nanocrystallisation from supersaturated solution and spray drying

71. NANOTUBES & NANOWIRES Self-assembling sheet of atoms arranged in the form of tubes and thread-like structures of nanoscale range Multiwalled carbon nanotubes are suitable delivery system for transformation specifically to bacterial cells ( E. coli)

72. CERAMIC NANOPARTICLES Nanoparticles made up of inorganic (ceramic) compounds such as silica, titania and alumina Size = less than 50nm Helps in evading reticuloendothelial system (RES) of body

73. SUMMARY Definition of nanoparticles Advantages Types of nanoparticles Polymers used Methodologies Novel nanoparticulate systems

74. REFERENCES Targeted and Controlled Drug Delivery, Novel Carrier System by S.P.Vyas and R.K.Khar , pg no: 331-381, Reprint 2008 www.wikipedia.com www.google.com