Matrix Tablets Flashcards
Describe matrix tablets
Extended release formulation
Body made of polymer network
Does not disintegrate when hydrated
What are the different types of matrix tablets?
Hydrophilic matrix tablet
Insoluble matrix tablet
What are the 2 drug release mechanisms for matric tablets?
Drug diffusion
Matrix erosion
Describe drug diffusion mechanism
Diffuse out down conc gradient + drug molecules dissolve
Drug molecules at edge of tablet diffuse out first
When does a matrix tablet rely on drug diffusion more?
Less soluble polymer matrix
Describe matrix erosion mechanism
Matrix on outside dissolves = exposes matrix inside
Then inside dissolves
Why may drug release limit drug absorption?
Drug must be released into + dissolved in GI fluids to be absorbed across GI mucosa
Why may drug solubility limit drug absorption?
Low drug solubility in GI fluids associated with slow drug dissolution + thus absorption
Why may GI permeability limit drug absorption?
Low GI mucosal permeability associated with slow drug diffusion across GI mucosa
What type of polymer is a hydrophilic matrix tablet?
Gel-forming polymer
How does hydrophilic matrix tablet work?
Combo of drug diffusion + matrix erosion
Swells upon hydration
Tablet gels from outside in
Gel layer form diffusion barrier
What is the drug release order of hydrophilic matrix tablet?
Zero or first order
What forms a hydrophilic matrix?
Natural gums
Cellulosics
Polyethylene glycol
How do you get a slower release of a hydrophilic matrix tablet?
Higher molecular weight
Higher proportion of polymer content
Higher degree of cross-linking
What does a higher molecular weight of hydrophilic matrix tablet cause?
Greater swelling
Less erosion
Slower release
