9df2controlled drug delivery sytem

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Presentation Transcript

Controlled Drug Delivery System : 

1 Controlled Drug Delivery System Presented By Mayank M. Sanghvi Dept. of pharmaceutics KLE University 1

Activation-modulated Drug Delivery System : 

2 Activation-modulated Drug Delivery System In this group of controlled release drug delivery system, the release of drug molecules from the delivery system is activated by some physical, chemical, or biochemical process and/or by energy supplied externally. The rate of drug release is then controlled by regulating the process applied or energy input. 2 2

Classification : By Physical Means : 

3 Classification : By Physical Means 3 Activation- Modulated DDS Osmotic pressure Activated 3

Osmotic Pressure Activated DDS : 

4 Osmotic Pressure Activated DDS 4 Drug reservoir ( API + osmotic agent) Delivery Orifice Semi-permeable Membrane. (cellulose esters) 4

Slide 5: 

5 For the drug delivery system containing a solution formulation, the intrinsic rate of drug release is defined by, Q Pw Am t hm For the drug delivery system containing a solid formulation, the intrinsic rate of drug release is defined by, Q Pw Am t hm 5 ( πs – πe ) = ( πs – πe ) Sd = 5

Slide 6: 

6 Where, Q/t - rate of drug release Pw - permiability of semipermiable housing Am -effective S.A. of semipermiable housing hm - thickness of semipermiable housing ( ps - pe) – Differential osmotic pressure b/w DDS with osmotic pressure ps & environmental osmotic pressure pe Sd – Aqueous solubility of drug contained in the solid formulation. 6 6

Slide 7: 

7 Release is controlled at rate determined by, Water permeability Surface area of semi-permeable housing Osmotic pressure gradient Merits : A high degree of in vivo- in vitro correlation (IVIVC) is obtained in osmotic systems. For oral osmotic systems, drug release is independent of gastric pH and hydrodynamic conditions. 7 7

Slide 8: 

8 8 Alzet Osmotic Pump 8

Classification : By Physical Means : 

9 Classification : By Physical Means 9 Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated 9

Hydrodynamic Pressure - Activated DDS : 

10 Hydrodynamic Pressure - Activated DDS 10 10

Slide 11: 

11 Rate of drug release is defined by, Where, Pf = fluid permeability Am = effective Surface area hm = thickness of wall with anular opening (qs - qe)= differential hydrodynamic pressure between DDS and environment. 11 Q Pf Am t hm = ( qs - qe) 11

Slide 12: 

12 Release is controlled at rate determined by, Fluid permeability Pressure gradient Surface area of wall with annular opening 12 12

Classification : By Physical Means : 

13 Classification : By Physical Means 13 Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated 13

Vapor Pressure – Activated DDS : 

14 Vapor Pressure – Activated DDS 14 14

Slide 15: 

15 The rate of drug release is defined by, Q = d4 (Ps -Pe) t 40.74 ml Where- Q/t - rate of drug release d - Inner diameter of cannula l - length of cannula (Ps -Pe) - the difference between the vapor pressure in the vapor chamber & pressure at the implantation site. m - viscosity of the drug solution. 15 15

Slide 16: 

16 Rate controlled By : Differential vapor pressure Formulation viscosity Size of the delivery cannula Example, An implantable infusion pump for constant infusion of heparin in anticoagulant treatment, morphine for patients suffering from the intense pain of terminal cancer. 16 16

Classification : By Physical Means : 

17 Classification : By Physical Means 17 Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated 17

Mechanically – Activated DDS : 

18 Mechanically – Activated DDS In this type, drug reservoir is in solution form retained in a container equipped with mechanically activated pumping system. A measured dose of the drug formulation is reproducible delivered in to a body cavity, for ex. The nose, through the spray head upon manual activation of the drug delivery pumping system. 18 18

Slide 19: 

19 Ex. Metered-dose Inhaler the volume of solution delivered is controllable, as small as 10-100 μl & is independent of the force & duration of the activation applied as well as the solution volume in the container. 19 19

Classification : By Physical Means : 

20 Classification : By Physical Means 20 Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated Magnetically Activated 20

Magnetically Activated - DDS : 

21 Magnetically Activated - DDS 21 21

Slide 22: 

22 In this type, drug reservoir is a dispersion of peptide or protein powders in polymer matrix from which macromolecular drug can be delivered only at a relatively slow rate. Device is fabricated by positioning a tiny magnet ring in core of hemispherical drug dispersing polymer matrix. The external surface is coated with drug impermeable polymer (ethylene vinyl acetate or silicone elastomer) except one cavity at the centre of the flat surface. 22 22

Slide 23: 

23 e.g. This delivery device used to deliver protein drugs such as bovine serum albumin, at a low basal rate, by a simple diffusion process under non triggering condition. As the magnet is activated to vibrate by an external electromagnetic field, the drug molecules are delivered at a much higher rate. 23 23

Classification : By Physical Means : 

24 Classification : By Physical Means 24 Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated Magnetically Activated Sonophoresis Activated 24

Sonophoresis - Activated DDS : 

25 Sonophoresis - Activated DDS This type of system utilizes ultrasonic energy to activate or trigger the delivery of drug from polymeric drug delivery device. System can be fabricated from nondegradable polymer (ethylene vinyl acetate) or bioerodiable polymer (poly[bis(p-carboxyphenoxy) alkane anhydride]. 25 25

Slide 26: 

26 26 26

Classification : By Physical Means : 

27 Classification : By Physical Means 27 Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated Magnetically Activated Sonophoresis Activated Ionto- phoresis Activated 27

Iontophoresis - Activated DDS : 

28 Iontophoresis - Activated DDS Iontophorsis can be defined as the process in which the flux or rate of absorption of ionic solutes into or through skin is enhanced by applying a voltage drop/electrical field across the skin. In addition, delivery rate can be controlled by the intensity of applied electric current or Electro-chemical potential gradient. 28 28

Slide 29: 

29 Iontophoresis – facilitated skin permeation rate of charged molecule (i) consist of 3 components & is expressed by, Jiisp = Jp + Je +Jc Jp – passive skin permeation flux. Je – electrical current driven permeation flux Jc = convective flow driven skin permeation flux 29 29

Slide 30: 

30 30 30

Merits : : 

31 Merits : Non-invasive technique as a substitute for chemical enhancers. Frequency of dosage is reduced. Provide predictable and extended duration of action. Demerits : Excessive current density leads to pain. The safe current density varies with electrode size. Mol. Wt. of 8000-12000 results in a uncertain rate of delivery. 31 31

Classification : By Physical Means : 

32 Classification : By Physical Means 32 Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated Magnetically Activated Sonophoresis Activated Ionto- phoresis Activated Hydration Activated 32

Hydration - Activated DDS : 

33 Hydration - Activated DDS 33 Valrelease Tablets 33

Slide 34: 

34 Not only hydrophilic polymer but also the lipophilic polymers, such as silicone elastomer, can be modified to have swelling properties. This is achieved by impregnating water-miscible liquid such as glycerol and/or water soluble salt such as, sodium chloride, in lipophilic polymer matrix. 34 34

Classification By : Chemical Means : 

35 Classification By : Chemical Means 35 Activation- Modulated DDS pH-Activated DDS 35

pH-Activated DDS : 

36 pH-Activated DDS This type of chemically activated system permits targeting the delivery of drug only in the region with selected pH range. It fabricated by coating the drug-containing core with a pH – sensitive polymer combination. For instances, a gastric fluid labile drug is protected by encapsulating it inside a polymer membrane that resist the degradative action of gastric pH, such as combination of ethyl-cellulose and hydroxymethylcellulose phthalate. 36 36

Slide 37: 

37 37 37

Classification By : Chemical Means : 

38 Classification By : Chemical Means 38 Activation- Modulated DDS pH-Activated DDS Ion-Activated DDS 38

Ion-Activated DDS : 

39 Ion-Activated DDS 39 39

Slide 40: 

40 An ionic or a charged drug can be delivered by this method & this system are prepared by first complexing an ionic drug with an ion-exchange resin containing a suitable counter ion. Ex. By forming a complex between a cationic drug with a resin having a So3- group or between an anionic drug with a resin having a N(CH3)3 group. The granules of drug-resin complex are first treated with an impregnating agent & then coated with a water-insoluble but water-permeable polymeric membrane. 40 40

Slide 41: 

41 This membrane serves as a rate-controlling barrier to modulate the influx of ions as well as the release of drug from the system. Limitations : The rate of release of the drug is directly proportional to the concentration of ions at the site of action. 41 41

Classification By : Chemical Means : 

42 Classification By : Chemical Means 42 Activation- Modulated DDS pH-Activated DDS Ion-Activated DDS Hydrolysis-Activated DDS 42

Hydrolysis-Activated DDS : 

43 Hydrolysis-Activated DDS This type of system depends upon hydrolysis process to activate the release of drug. Drug reservoir is either encapsulated in microcapsules or homogeneously dispersed in microspheres or nano particles for injection. 43 43

Slide 44: 

44 It can also be fabricated as an implantable device. All these systems prepared from bioerodible or biodegradable polymers (polyanhydride, o-ester). It is activated by hydrolysis-induced degradation of polymer chain & is controlled by rate of polymer degradation. Ex. LHRH – releasing biodegradable subdermal implant, which is designed to deliver goserline, a synthetic LHRH analog for once a month treatment of prostate carcinoma. 44 44

Classification By : Biochemical Means : 

45 Classification By : Biochemical Means Enzyme - Activated Drug Delivery System This type of biochemical system depends on the enzymatic process to activate the release of drug. Drug reservoir is either physically entrapped in microspheres or chemically bound to polymer chains from biopolymers (albumins or polypeptides). 45 45

Slide 46: 

46 The release of drug is activated by enzymatic hydrolysis of biopolymers (albumins or polypeptides) by specific enzyme in target tissue. Ex. Albumin microspheres release 5 – fluorouracil in a controlled manner by protease – activated biodegradation. 46 46

Feedback Regulated Drug Delivery System : 

47 Feedback Regulated Drug Delivery System In this group the release of drug molecules from the delivery system is activated by a triggering agent. Rate of drug release is controlled by concen. of triggering agent. They are further classified as Bioerosion -regulated drug delivery system Bioresponsive drug delivery system Self-regulating drug delivery system 47 47

A. Bioerosion - Regulated DDS : 

48 A. Bioerosion - Regulated DDS 48 48

.Bioresponsive DDS : 

49 .Bioresponsive DDS in this type, the drug reservoir is contained in a device enclosed by bio-responsive membrane whose drug permeability is controlled by conce. of biochemical agent. e.g. glucose-triggered insulin drug delivery system. 49 49

Slide 50: 

50 50 50

C. Self-Regulating DDS : 

51 C. Self-Regulating DDS This type of system depends on a reversible & competitive binding mechanism to activate and to regulate the release of drug. Drug reservoir is drug complex encapsulated within a semi permeable polymeric membrane. The release of drug from the delivery system is activated by the membrane permeation of biochemical agent from the tissue in which the system is located 51 51

Slide 52: 

52 52 52

Effect Of System Parameters On CDDS : 

53 Effect Of System Parameters On CDDS 53 Polymer & Solution Solubility Polymer & Solution Diffusivity Thickness of polymer diffusion path & hydro- dynamic layer Partition Co-efficient Surface Area Loading Dose 53

Polymer Solubility : 

54 Polymer Solubility For drug to be release, the drug molecules on the outmost surface must dissociate from its crystal lattice structure, partition or dissolve in surrounding medium. As the solubility of drug particles in rate controlling membrane and polymer matrix plays rate-controlling role in release from a polymeric device. To release at an appropriate rate the drug should have adequate polymer solubility. Rate of drug release is directly proportional to magnitude of polymer solubility. 54

Solution Solubility : 

55 Solution Solubility Aqueous solubility varies from one drug to another. Difference in aqueous solubility is depend on the difference in their chemical structure, types & physicochemical nature of functional groups & the variations in their stereo chemical configurations. Drug release increases with increase in Solution solubility of drug. 55

Partition Coefficient : 

56 Partition Coefficient Partition co-efficient K of a drug for it’s interfacial partitioning from the surface of a drug delivery device towards an elution medium as given : K = Cs/Cp Where, Cs = conc. Of drug at the solution/polymer interface Cp = solubility of drug in the polymer phase. 56

Slide 57: 

57 Any variation in either Cs or Cp result in increase or decrease in magnitude of ‘K’ value. Rate of drug release increase with increase in partition coefficient 57

Polymer Diffusivity : 

58 Polymer Diffusivity The diffusion of small molecules in a polymer structure is a energy activated process in which the diffusant molecules move to a successive series of equilibrium positions when a sufficient amount of energy of activation for diffusion Ed, has been acquired by the diffusant & it’s surrounding polymer matrix. 58

Slide 59: 

59 Magnitude of polymer diffusivity is dependant upon type of functional group and type of stereo chemical position in diffusant molecule. The bulkier the functional group attached to polymer chain lower the polymer diffusivity. Polymer diffusivity also depends on , 1) Effect of cross linking (inverse relationship) 2) Effect of crystallinity (inverse relationship) 3) Effect of fillers 59

Solution Diffusivity : 

60 Solution Diffusivity The diffusion of solute molecules in solution medium is a result of the random motion of molecules. Under concentration gradient molecule diffuse spontaneously from higher concentration to lower concentration. Diffusivity of solute molecule in aqueous solution usually decreases as its concentration increases 60

Slide 61: 

61 Thickness of hydro- dynamic diffusion layer Surface Area Loading Dose. 61

Reference : 

62 Reference Novel Drug Delivery System- Y.W.Chien. published by Marcel Dekkar, inc., New York Pg no. 17-36 & 57-111 Controlled And Novel Drug Delivery – N.K.Jain CBS Publishers & Distributors, New Delhi. www.pharmainfo.net 62

Slide 63: 

63 Thank you!!!

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