Design & development of implantable products: By Bhupendra Yadav


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Implants are cylindrical, monolithic devices of millimeter or centimeter dimensions, implanted into the subcutaneous or intramuscular tissue by an minor surgical incision or injected through a large bore needle; and release the incorporated drug in a controlled manner, allowing the adjustment of release rates over extended periods of time, ranging from several days up to one year.

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Design & development of implantable products: By Bhupendra Yadav

  1. 1. Design & Development of Implantable Products Presented by: BHUPENDRA Ku YADAV M.Pharm II sem RCPSR, Bhilai, (C.G.) 1
  2. 2. Introduction     Implants are cylindrical, monolithic devices of millimeter or centimeter dimensions, implanted into the subcutaneous or intramuscular tissue by an minor surgical incision or injected through a large bore needle; and release the incorporated drug in a controlled manner, allowing the adjustment of release rates over extended periods of time, ranging from several days up to one year. Implantable drug delivery systems are placed completely under the skin. The patient is aware of only a small bump under the skin. Designed to transmit drugs and fluids into the bloodstream without the repeated insertion of needles. Well suited to the drug delivery requirements of insulin, steroids, chemotherapeutics, antibiotics, analgesics, total parenteral nutrition, and heparin. There is little chance of infection or interference with daily activities Because the device is completely subcutaneous, with no opening in the skin. 2
  3. 3. Anatomy & Physiology of Skin Features:•Subcutaneous tissue is essentially a sheet of areolar tissue lying directly underneath the skin. •It is rich in fat, but poor in nerve network & hemoperfusion. Therefore, the subcutaneous tissue is an ideal location for implantation, slow drug absorption & low reactivity to the insertion of foreign materials. 3
  4. 4. Ideal Properties of Implants       Biostable Biocompatible Non-toxic & non-carcinogenic Minimum surface area & smooth texture Easily removable Medicament Release Rate 4
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  7. 7. Design & Fabrication Approaches For The Development of Implantable Products: (a) Controlled drug delivery by diffusion process:    Polymer membrane permeation- controlled drug delivery:a) Nonporous membranes b) Micro porous membranes c) Semi permeable membranes Matrix diffusion-controlled drug delivery:a) Lipophilic Polymers b) Hydrophilic(swellable) polymers c) Porous polymers Micro reservior partition- controlled drug delivery system:a) Hydrophilic reservoir/Lipophilic matrix b) Lipophilic reservoir/Hydrophilic matrix 7
  8. 8. (b) Controlled drug delivery by activation process:      Osmotic pressure Vapor pressure Hydration Hydrolysis Magnetism (c) Controlled drug delivery by feed back regulated mechanism:  Bioerosion 8
  9. 9. Controlled drug delivery by diffusion process A) Membrane permeation- controlled drug delivery:-  Here the drug formulation is totally or partially encapsulated within a drug reservoir compartment and  the drug release surface is covered by a rate limiting polymeric membrane having a specific permeability for drug. drug reservoir polymeric membrane Drug contained in a formulation • 1. 2. Encapsulation of drug formulation in to the reservoir compartment can be done by: Spray coating 9 microencapsulation
  10. 10. Different shapes of the systems like sphere , cylinder or sheet can be fabricated Example:- A NORPLANT SUBDERMAL IMPLANT , PROGESTASERT IUD, and OCUSERT SYSTEM.  b) Matrix diffusion-controlled drug delivery:    The drug reservoir is prepared by homogenous dispersion of drug particles in a rate controlling polymer matrix fabricated from either a lipophillic or a hydrophilic polymer. The drug dispersion in a polymer matrix is done by a) Blending finely divided drug particles with a liquid polymer or a viscous base followed by cross linking of the polymer chain b) Mixing the drug with a polymer at an elevated temperature c) Dissolving drug and polymer in a common solvent followed by solvent evaporation at elevated temperature or under vacuum The resultant drug polymer dispersion is then molded or extruded to form a drug delivery devices of various shapes 10
  11. 11.  Example:- Contraceptive Vaginal Ring Syncro-Mate B Implants Compudose Implant c) Micro reservoir Partition- Controlled drug delivery: Drug Reservoir- fabricated by aqueous suspension of a drug using high energy dispersion technique into a biocompatible polymer such as silicon elastomer to form a homogenous dispersion of microscopic drug reservoir.  Depending on the physiochemical properties of the drug and the desired rate of drug release, the device can be further coated with polymer to modify mechanism & rate of release. Example:- Syncro-Mate C Implants Dual-Release Vaginal Contraceptive Ring 11
  12. 12. Polymer matrix Microscopic Drug reservoir {liquid compartment} Coating membrane Polymer -solution interface 12
  13. 13. Controlled drug delivery by activation process  Osmotic pressure activated drug delivery system:  In this type of controlled drug delivery system the release of the drug takes place due to osmotic pressure. Osmosis is the movement of a solvent through a semi-permeable membrane from a region of low- solute concentration to a region of highsolute concentration.  13
  14. 14.     Drug reservoir which can be either a solid or a suspension is contained in a semi permeable housing . The release is activated through a specially formed orifice and rate of release is modulated by controlling the osmotic gradient. The release rate is dependent of: water permeability of membrane, solubility of osmogen, effective surface area of semipermeable housing Representatative example of this type of implantable controlled release drug delivery system is: ALZET Osmotic Pump DUROS Osmotic Pump 14
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  17. 17.  Vapor pressure-activated implantable drug delivery system:  The drug reservoir which is a solution formulation is contained in to an infusate chamber. By freely movable bellow the chamber is a pumping system physically separated from the vapors pressure chamber which contains vaporizable fluids such as a fluorocarbon. The fluorocarbon vaporizes at body temperature creating a vapor pressure that pushes bellow to move upward and forces the drug solution to get delivered .   17
  18. 18.  Magnetism – Activated Drug Delivery: 18
  19. 19.  Bioerosion regulated drug delivery system:  This system consist of a drug dispersed in to a biodegradable polymer matrix like poly vinyl methyl ether and is coated with immobilized urease in a neutral pH. In the presence of urea, urease at the surface of drug delivery system metabolize urea to form ammonia causing increase in pH at which polymer degrades leading to drug release.  Hydrocortisone release Urease U U U U U Erosion U U Hydrocortisone U Urea Ammonia Alkaline pH U U U U U U U Polymer 19
  20. 20. Targeted Drug Delivery With Catheterized Osmotic Pumps:  Catheters of different designs can be attached to the exit port of an osmotic pump for targeted drug delivery 20
  21. 21. Electrical Regulated Release: Device features:  Target: 1+ year implant life.  100 to 400 doses.  Reservoir volume ≥100 nL.  Accommodates solutions, solids.  Individual reservoirs activated electronically  – Each reservoir can contain a different drug or formulation 21
  22. 22.  E.g. Silicon Microchip  contained an array of reservoirs attached in silicon. The reservoirs were capped with gold membranes that could be electrochemically dissolved in saline with an applied voltage (through a wireless signal from outside the body). At approximately 1 V, gold chloride is formed, causing the membrane to dissolve. 22
  23. 23. Micrographs of gold membranes (a) before and (b) after electrochemical dissolution 23
  24. 24. Advantages: ◦ Controlled drug delivery for over a long time (months/years) ◦ Improve patient compliance ◦ Targeted drug delivery ◦ Bypass first pass metabolism ◦ Decrease side effects ◦ Improved stability of drug ◦ Improve availability of drugs Disadvantages: - mini-surgery is needed - uneasy to simply discontinue the therapy - local reactions 24
  25. 25. Any Queries 25
  26. 26. Thanks 26