Chapter 9 Part 2 Flashcards by amanda kastel

what is the difference between OROS and OROS push pull?

both are osmotic pumps

OROS was made first. In this design, the osmotic agent added to create a buildup of osmotic pressure exited WITH THE DRUG resulting in a short duration

OROS push pull is the 2nd generation where 1 partition contains only the drug and 1 partition contains only the osmotic agent. water will go in to dissolve the drug but the osmotic agent will not come out

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true or false

for an osmotic pump, the size of the tablet does not have an effect on how much drug is released

false - it does.

this means a larger surface area, which is one of the factors that controls the drug release for osmotic pumps.

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when a patient is picking up a tablet that is an osmotic pump design, what is an important cousneling point?

-it’s normal to see the full tablet in feces (only the drug comes out through orifice and tablet itself remains intact)

-DO NOT CHEW - the full daily dose will come out

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true or false

in an osmotic pump, if the orifice is large the drug release will be large

true

3 factors control drug release:

-type of membrane
-diameter of drug release orifice
-surface area

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true or false

it is possible to get a steady state plasma profile through use of Procardia XL

true
(osmotic pump)
can provide zero order

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what can be added to the tablet of an osmotic pump design to increase the osmotic pressure

NaCl or dextrose

NaCl preferred bc 0.5mol is needed to have same effect as 1 mol of dextrose

also, MW is smaller so tablet doesn’t have to be as big

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what is delayed release oral dosage form

the drug release from the dosage form is delayed until it reaches the site of absorption

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TRUE OR FALSE

enteric coating is a delayed release oral dosage form

true

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true or false

osmotic pumps cannot provide zero order drug release

false - it can

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give 5 examples of drugs that are delayed release oral dosage forms

erythromycin delayed release tablets (E-mycin)

Erthromycin delayed release capsules

Asacol (mesalamine) delayed release tablets

prilosec (omeprazole) delayed release tablets

Ecotrin (aspirin)

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release mechanism of hydrophilic matrix

dissolution or diffusion – slowly erodes

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release mechanism of inert plastic matrix

diffusion

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release mechanism of microparticulate reservoir (microencapsulated drug)

diffusion

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release mechanism of osmotic tablets

osmotic pressure

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release mechanism of ion exchange

pH or ion displacement

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release mechanism of single reservoir

diffusion

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release mechanism of hybrid microparticulate reservoir in matrix (coated beads, granules, and microspheres)

diffusion

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of the different types of technology for extended release, which 3 are NOT limited to just diffusion as a mechanism

hydrophilic matrix - dissolution/diffusion

osmotic tablets - osmotic pressure

ion exchange - pH or ion displacement

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micro K uses what extended release technology?

microencapsulated drug - diffusion system: Reservoir Devices

Diffusion systems: reservoir devices

explain the components.

what determines the rate of release of the drug from the system?

a core of drug in a RESERVOIR, surrounded by a polymeric membrane

the nature of the membrane determines the rate of release of the drug from the system

give 2 advantages of diffusion systems: reservoir devices

zero order release is possible (bc membrane)
the release rate is variable with the type of polymer

give 3 DISADVANTAGES of diffusion systems: reservoir devices

cost
if system fails - toxicity
bad for high MW compounds bc has to diffuse through membrane

need surgery to remove the system from implants dont worry – not a concern for oral tablet

diffusion systems: reservoir devices

flux is what?
what does it depend on?

flux represents the release pattern from the device

dependent on the diffusion coefficient

true or false

diffusion systems: reservoir devices is a membrane type delivery system and can provide zero order release

TRUE

True or false diffusion systems: reservoir devices are fairly easy to make

false - difficult

Diffusion systems: matrix devices explain what it consists of

drug homogeneously dispersed throughout a polymer MATRIX

explain how matrix devices (diffusion system) work

the drug in the outside layer of the matrix is exposed to the solution. Water rushes in and swells the granules (inc surface area) and the drug dissolves and diffuses out of the matrix. this process continues and the interface between the bathing solution and solid drug moves closer and closer to the interior ghost zone matrix increases in thickness as drug dissolves

give 2 advantages of matrix devices over reservoir devices as diffusion systems

easier to produce than reservoir CAN deliver high MW compounds bc it does not have to go through membrane

give 2 disadvantages of matrix devices compared to reservoir as a diffusion system

CANNOT obtain zero order release for implanted systems, the removal of remaining matrix is necessary (not conern for oral) use biodegradable polymer as a solution

true or false for matrix devices, the release rate (rate of diffusion) decreases as time goes on and this is why zero order is not possible

TRUE

give an example of a drug that is part of this: Dissolution systems: encapsulated and matrix dissolution systems

spansule

explain how: dissolution systems: encapsulated and matrix dissolution systems works

there can either be alternate layers of rate controlling drugs OR a group of beads with different coatings (such is the case for Spansule) in the case of Spansule: some beads are only the drug in the polymeric matrix and some are the drug in the polymeric matrix PLUS a polymeric membrane. in the case of alternate layers: varied thicknesses. the more thick the dissolving coat, the slower the release

true or false controlled release drugs can be a good source for compounding just like immediate release

FALSE - not a good source

what USP chapter describes the appropriate drug release profile for modified release dosage form?

USP chapter 724

what USP chapter defines the uniformity of dosage units

USP 905

aspirin delayed release tablets must be labeled as....

enteric coated

theophylline extended release capsules must have what label

for dosing every 12 or 24 hours

what year was a guidance document released for in vitro and in vivo correlations? who published it and what is it called?

1997 FDA extended release oral dosage forms: Development, Evaluation, and application of in vitro/in vivo correlations

name all of the pH's that the device that mimics the GI tract contains, and what each pH value represents

pH 7.5 - distal ileum pH 7.2 - like proximal ileum pH 6.8 - like lower small intestines pH 4.5 - like upper small intestines pH 1.2 - like stomach

true or false both immediate release and modified release are required to have a drug release profile

flase - for immediate release it's called a drug DISSOLUTION profile

Diffusion System: Reservoir Devices

Microencapsulation Micro-K K-dur Effexor XR

Diffusion Systems: Matrix Devices

Drug embedded in Inert plastic matrix Granumet Probanacid

Dissolution Systems

Encapsulated: Spansule Matrix: Hydrophilic/slowly eroding matrix

explain how dissolution systems work

both encapsulated and matrix, and then there's repeat doses encapsulated: Drug dissolved in hydrophilic polymer. surrunded by hydrophilic membrane. dissolves matrix: drug dissolved in hydrophilic polymer. Drug dissolves with the polymer -- SLOW EROSION - embedded in hydrophilic matrix type (SlowK oramorph, etc) end of treatment-all is dissolved - full tab NOT in feces

explain how a reservoir device diffusion system CAN give zero order while a matrix device diffusion system cannot

membrane is constant thickness in matrix, ghost zone continually getting thicker and release time continually increases as space from core increases