Diffusion Controlled Release Flashcards
What about control release from a matrix
Drug particles are dispersed they a water insoluble matrix
The rate of drug release will depend on the rate of drug diffusion which should be much slower than the drug dissolution within matrix
What’s a reservoir membrane device
Water insoluble polymeric material that encases a core drug
Drug will go into membrane and exchange with the fluid surrounding the particles or tablet
What is the hybrid sandwich controlled release
A combination of both reservoir membrane and matrix type of design
Offers the advantage of constant release zero order and mechanical superiority of matrix diffusion
Erosion controller release
The core drug is contained by partially soluble or erodible membrane and the drug will diffuse through the pores which have been formed in the polymer coat
Diffusion and dissolution with a swelling membrane–controlled release
The coating swells to control the diffusion of the drug
Allows the entrance of water to dissolve the drug but controls the drug diffusion to the surrounding medium
Ion exchange resins
High concentration of charged ion in hit is in contact with ion exchange group of resin the drug molecule is exchanged with the ion the diffuses out of resin
How to control the ion exchange resin further
Coat the drug resin complex by micro encapsulation process
Coated and uncoated drug resin complex can be mixed and filled into capsules
Also coat the resin granules in water permeable polymer
Osmotically controlled release pros system by alza
A semi preamble core surrounding a core of osmotically active drug or instead an osmotically active salt
The coating membrane is imperable to drugs but instead to GI fluid
Delivery orifice drilled in coating membrane and GI fluids make inside swell and fluid comes out
