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    controlled drug delivery system classification controlled drug delivery system classification Presentation Transcript

    • Controlled Drug Delivery System Classification
    • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification : By Physical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS Osmotic pressure Activated
    • Osmotic Pressure Activated DDS 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Drug reservoir ( API + osmotic agent) Delivery Orifice Semi-permeable Membrane. (cellulose esters)
      • 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
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. ( π s – π e ) = ( π s – π e ) Sd =
      • Where,
      • Q/t - rate of drug release
      • P w - permiability of semipermiable housing
      • A m -effective S.A. of semipermiable housing
      • h m - thickness of semipermiable housing
      • ( π s - π e ) – Differential osmotic pressure b/w
      • DDS with osmotic pressure p s &
      • environmental osmotic pressure p e
      • Sd – Aqueous solubility of drug contained in the
      • solid formulation.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Alzet Osmotic Pump
    • Classification : By Physical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated
    • Hydrodynamic Pressure - Activated DDS 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • Rate of drug release is defined by,
      • Where,
      • P f = fluid permeability
      • A m = effective Surface area
      • h m = thickness of wall with anular opening
      • (  s -  e ) = differential hydrodynamic pressure
      • between DDS and environment.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Q Pf Am t hm = (  s -  e )
      • Release is controlled at rate determined by,
      • Fluid permeability
      • Pressure gradient
      • Surface area of wall with annular opening
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification : By Physical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated
    • Vapor Pressure – Activated DDS 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • The rate of drug release is defined by,
      • Q = d 4 (P s -P e )
      • t 40.74 ml
      • Where-
      • Q/t - rate of drug release
      • d - Inner diameter of cannula
      • l - length of cannula
      • (P s -P e ) - the difference between the vapor pressure in the vapor chamber & pressure at the implantation site.
      • m - viscosity of the drug solution.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification : By Physical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated
    • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • Ex. Metered-dose Inhaler
      • the volume of solution delivered is controllable, as small as 10-100 μ l & is independent of the force & duration of the activation applied as well as the solution volume in the container.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification : By Physical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated Magnetically Activated
    • Magnetically Activated - DDS 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification : By Physical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated Magnetically Activated Sonophoresis Activated
    • 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].
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification : By Physical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated Magnetically Activated Sonophoresis Activated Ionto- phoresis Activated
    • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • Iontophoresis – facilitated skin permeation rate of charged molecule (i) consist of 3 components & is expressed by,
      • J i isp = J p + J e +J c
      • J p – passive skin permeation flux.
      • J e – electrical current driven permeation flux
      • J c = convective flow driven skin permeation flux
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification : By Physical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS Osmotic pressure Activated Hydrodynamic Press. Activated Vapor Pressure Activated Mechanically Activated Magnetically Activated Sonophoresis Activated Ionto- phoresis Activated Hydration Activated
    • Hydration - Activated DDS 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Valrelease Tablets
      • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification By : Chemical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS pH-Activated DDS
    • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification By : Chemical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS pH-Activated DDS Ion-Activated DDS
    • Ion-Activated DDS 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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 So 3 - group or between an anionic drug with a resin having a N(CH 3 ) 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Classification By : Chemical Means 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. Activation- Modulated DDS pH-Activated DDS Ion-Activated DDS Hydrolysis-Activated DDS
    • 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 .
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 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).
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 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
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • A. Bioerosion - Regulated DDS 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • .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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 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
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • Effect Of System Parameters On CDDS 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • Polymer & Solution Solubility
      • Polymer & Solution Diffusivity
      • Thickness of polymer diffusion path & hydro-
      • dynamic layer
      • Partition Co-efficient
      • Surface Area
      • Loading Dose
    • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 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.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 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 = C s /C p
      • Where,
      • C s = conc. Of drug at the solution/polymer interface
      • C p = solubility of drug in the polymer phase.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • Any variation in either C s or C p result in increase or decrease in magnitude of ‘ K ’ value.
      • Rate of drug release increase with increase in partition coefficient
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 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 E d , has been acquired by the diffusant & it ’ s surrounding polymer matrix.
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • 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
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 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
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
      • Thickness of hydro- dynamic diffusion layer
      • Surface Area
      • Loading Dose.
    • 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
      22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P.
    • 22/01/2011 B R Nahata College of Pharmacy ,Mandsaur M.P. ?