Chapter 9 Part 2 Flashcards
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
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.
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
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
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
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
what is delayed release oral dosage form
the drug release from the dosage form is delayed until it reaches the site of absorption
TRUE OR FALSE
enteric coating is a delayed release oral dosage form
true
true or false
osmotic pumps cannot provide zero order drug release
false - it can
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)
release mechanism of hydrophilic matrix
dissolution or diffusion – slowly erodes
release mechanism of inert plastic matrix
diffusion
release mechanism of microparticulate reservoir (microencapsulated drug)
diffusion
release mechanism of osmotic tablets
osmotic pressure
release mechanism of ion exchange
pH or ion displacement
release mechanism of single reservoir
diffusion
release mechanism of hybrid microparticulate reservoir in matrix (coated beads, granules, and microspheres)
diffusion
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
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
