ADT Exam 1

Card Set Information

Author:
Rx2013
ID:
107917
Filename:
ADT Exam 1
Updated:
2011-10-10 21:38:17
Tags:
Trans dermal Drug Delivery
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Description:
Trans-dermal Drug Delivery
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  1. The trans-dermal route is of particular interest for drugs that
    • have a short half life
    • undergo extensive 1st pass metabolism
    • require frequent dosing
  2. Advantages of TDD systmes
    • no first pass
    • sustained therapeutic drug levels
    • self administration
    • non invasive
    • allows removal of drug
  3. limitations of TDD
    • poor diffusion of large molecules
    • skin irritation
  4. Most important barrier to drug absorption via TDD
    • stratum corneum
    • keratinized cells
    • protein rich
    • intercellular lipid layers
  5. Transport = Flux=(mg/cm2/sec)=P x A x (Cd-Cr)

    Permeability Coefficient = P = [D x K(cm/sec)]/h
    • A= surface area of patch
    • D= diffusivity of drug in membrane (skin)
    • K= partition coefficient (patch/skin)
    • C= concentration in patch or skin
    • h= thickness of membrane (skin)
  6. TDD drug candidate
    • <20 mg/day
    • half life less than 10 hours
    • molecular weight < 500 daltons
    • melting point < 200 celcius
    • skin permeability
    • partition coeficient between -1 and 4
  7. Provides protection from external factors during application period
    backing
  8. moderates rate of drug release
    • membrane
    • could be skin
  9. maintains contact with pt skin and incorporates drug and excipients
    adhesive
  10. protects patch during storage; removed prior to application
    liner
  11. Matrix patch
    skin controls rate of diffusion
  12. reservoir patch
    • drug in reservoir with rate controlling membrane
    • used for drugs that are quickly absorbed
  13. drug in adhesive multi layer
    • membrane in patch controls rate
    • use for drugs that are quickly absorbed
  14. drug in adhesive single layer patch
    • skin controls rate of difusion
    • drug dispersed in adhesive
  15. Drug in adhesive patches
    • simple construction
    • complex formulation
    • skin controlled delivery
    • skin conformability
    • can be a smaller size
    • low dose dumping potential
  16. Reservoir patches
    • complex construction
    • simple formulation
    • membrane controlled delivery
    • poor skin conformability & multiple layers
    • cannot be a smaller size
    • dose dumping potential

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