316 Dissolution and Degradation Quiz

ndifranco94's version from 2015-09-21 17:49


Question Answer
Dissolutionrapid solubilization/breakup of a drug delivery device
Dissolution systems are composed ofdrug, inert matrix, carriers
Degradationslower breakdown of matrix in which drug is entrapped
Matrix for degradation is usuallypolymer
Cumulative release curve for dissolution/degradation FASTER than drug release
Cumulative release curve for degradation SLOWER than drug release
Cumulative release curve for degradation on the SAME TIME SCALE as drug release
Release rate of spaingly soluble drugs at low loading in polymer?same time scale as polymer degradation
Factors that affect degradationhydrophobicity, crosslinker size/conc, molecular weight of polymer chains, crystallinity, drug loading
Drug loading conc above which microvoids appear?10%
Microvoidschannels of all drug that have faster diffusion than rest of drug that has to traverse polymer
5 FDA approved degradable polymerspolydioxanone, poly(caprolactone), poly(glycolic acid), poly(lactic acid), polyanhydride
Does the FDA approve polymers?NO, they approve deivces and the polymer used in a specific context!
How do hydrophobicity and crystallinity affect degradation?water must enter prior to degradation, which is controlled by hydrophobicity and polymer matrix morphology
Three forms of diffusion in drug delivery systemsDiffusion of DRUG OUT of device, Diffusion of WATER IN, Diffusion of DRUG INTO THE BODY
Polyester degradationfirst order relationship
When does diffusion coeff increase?when the solute is in a hydrated phase
Bulk erosionpolymer disappears uniformly throughout a matl
Surface erosionpolymer disappears from a surface so that the matrix becomes progressively smaller w/ time
Why is surface erosion preferred?predictable release, constant rate of erosion depending on the surface area of the polymeric matrix
Factors that determine erosion kinetics of polymermostly combination of surface and bulk erosion, complicated by drug molecules affecting water penetration, water soluble drug release creates addl route for water entry
Biodegradable PolymersMOST = polyesters, covalent, polar bond that is broken down by hydrolysis at the C-O bond,
Products of ester breakdownalcohol (-COH) + acid (-COOH)
Hydrolysisbreakdown of a molecule in the presence of water
Inverse of hydrolysiscondensation (ex. alcohol + acid = ester)
Anhydrideless polar than ester,
Bulk degradationeasy water diffusion, hydrophilic polymers
Bulk erosion characteristicsrate of water diffusion in is HIGHER than rate of polymer transformation
Example of bulk erosionsugar cube, develops voids
Surface erosion characteristicslimited water penetration, hydrophobic polymers, grows thinner w/ time, polymer breakdown is FASTER than water penetration, rare (polyanhyides)

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