pharmaceutics > simburg controlled release > Flashcards

simburg controlled release Flashcards

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1
Q

controlled-release dosage forms regulate the _________ of drug release to achieve sustained, targeted, or delayed delivery

A

rate and timing

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2
Q

controlled release dosages can respond to physiology based on factors like ____. an example of this dosage form is _____

A

pH or environment, enteric coatings

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3
Q

controlled release dosages can be steady/ constant release when they ________. an example of this dosage form is ______

A

continuously, slowly release

zero-order release tablets

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4
Q

controlled release dosages can be biphasic, meaning the drug is released with __________. an example of this dosage form is ________

A

an initial burst followed by slow release

multilayered tablets

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5
Q

what is the purpose of enteric coated dosages? (3)

A

1 protect drug from degradation by gastric acid
2 prevent gastric irritation
3 control odor/taste

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6
Q

at low pH: enteric coating is ______ while at high pH, enteric coating _____

A

intact

polymer ionizes (COOH->COO-), dissolves, releases drug

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7
Q

enteric coatings are predominantly _________

A

negatively charged polymers

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8
Q

what are 2 common enteric coating polymers

A
  1. cellulose ester and phthalic acid esters
    eg. hydroxypropyl methylcellulose phthalate
  2. copolymer of methacrylic acid and ethyl methacrylate
    eg. eudragit
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9
Q

you would expect an enteric coating to be (ionized/unionized) in the stomach and (ionized/unionized) in the intestine

A

unionized

ionized

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10
Q

what are drugs made for colon delivery made of?

A

polymers that dissolve at pH>8 (terminal ileum)

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11
Q

How to make an enteric coating that dissolves in the colon
but not in the duodenum?
a) Add strong acidic groups to the polymer
b) Add weak acidic groups to the polymer
c) Use a hydrophobic polymer

A

b) Add weak acidic groups to the polymer

weak acids stay protonated all the time. requires a very high pH (colon) to remove protons

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12
Q

immediate release meds are dosed _____ while slow release meds are dosed ____

A

multiple times a day, once daily

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13
Q

which would have a better stable plasma level:
slow release or immediate release?

A

slow release

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14
Q

which would have fewer side effects:
slow release or immediate release?

A

slow release

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15
Q

for first order release, the fraction of drug release per unit time is _____

A

constant

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16
Q

for zero-order release, the amount of drug released per unit time is _____

A

constant

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17
Q

the curve of a first order reaction is _____ while the curve of a zero-order reaction is ____

A

exponential, linear

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18
Q

which kinetic type is ideal for stable plasma levels

A

zero-order

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19
Q

biphasic systems have an outerlayer for _____ and an inner core for ______

A

immediate release, slow, sustained release

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20
Q

when is a biphasic system prefered?

A

when you want rapid onset with prolonged effect

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21
Q

Which release form achieves a more stable plasma profile in
plasma?
a) 1st order
b) Zero order
c) Immediate release
d) Plasma levels do not depend on the rate of release

A

b) Zero order

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22
Q

Which drug would benefit from a slow-release form?
a) drug with a narrow absorption window
b) drug with a broad absorption window

A

b) drug with a broad absorption window

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23
Q

The prolonged release form would make more sense for:
a) drug with fast plasma clearance (short half-life)
b) drug with slow plasma clearance (long half-life).

A

a) drug with fast plasma clearance (short half-life)

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24
Q

The prolonged release form would make most sense for:
a) drug with fast GI absorption (high permeability)
b) drug with slow GI absorption (low permeability)

A

a) drug with fast GI absorption (high permeability)

b) incorrect because it is already slow

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25
The prolonged release form would not be appropriate for: a) drug with poor solubility b) drug with high solubility
a) drug with poor solubility
26
diffusion (coating)-controlled release is:
drug surrounded bt polymer film release depends on coating thickness, porosity, solubility
27
erosion (matrix)-controlled release is:
drug embedded in slowly eroding polymer that delays rapid release
28
erosion (matrix)-controlled release prevents rapid release via (3)
1 binding the drug 2 slowing down water penetration 3 slow degradation by hydrolysis
29
which erosion (matrix)- controlled release polymer slows water penetration
xantham gum, hypromellose
30
which erosion (matrix)- controlled release polymer slows degradation by hydrolysis
poly-lactic acid
31
swellable hydrogels are:
long chain polymers that form a 3d network that expands upon hydration, thereby releasing the drug
32
osmotic-controlled (OROS system) uses __ for __
osmotic pressure for constant drug release
33
a osmotic-controlled (OROS system) consists of (3)
drug core, osmotic salts, semipermeable cellulose acetate coating
34
T/F: osmotic-controlled (OROS system) drug release is dependant on concentration of drug
False. drug depends on osmotic pressure, not concentration of drug (zero order)
35
what part of the OROS system allows for drug to slowly release once osmotic pressure builds?
semipermeable cellulose acetate membrane
36
What type of drugs are good for OROS? * Long half-life * Poorly penetrating the intestine * Water insoluble * Narrow therapeutic window
* Narrow therapeutic window
37
Ideal drugs for OROS: ___ half life ___ water solubility ___ therapeutic window ___ intestinal permeability
short good narrow good
38
gastroretentive systems (GRDDS) are used to
prolong gastric residence for drugs absorbed in the upper GI tract
39
how do gastroretentive systems (GRDDS) work? (2)
Mucoadhesive coatings – stick to mucosa Floating/swellable systems – retain in stomach
40
when does dose dumping occur?
wen release-rate-controlling mechanism is broken or if ethanol is consumed
41
how is quality measured in QC tests? (5)
General appearance Thickness Hardness & Friability Chemical uniformity Drug release (Dissolution test)
42
what does capping mean? what causes is?
top/bottom crown separates binder, moisture, improper pressure
43
what does lamination mean? what causes it?
layers split compression or lubrication problem
44
what does mottling mean? what causes it?
uneven color moisture or color migration
45
what is cracking/peeling? what causes it?
defective coating insufficient plasticizer or over-dried polymer
46
what is the point of dissolution testing?
to asses drug release in vitro in order to predict bioavailability
47
as surface areas increases, dissolution _____
increases
48
as the boundary layer thickness increases, dissolution _____
decreases
49
how do you increases surface area
micronization, nanosizing
50
how do you decrease boundary layer thickness?
surfactants (improve wettability), stirring
51
USP I - basket should be used for _____
floating forms (capsules, beads)
52
USP II - paddle should be used for ____
tablets, suspensions
53
dissolution tests are used to: (4)
1 detect variations in manufacturing 2 validate formulation consistency 3 basis for in vitro-in vivo correlation 4 generic drug approval
54
Which of the following parameters of the manufacturing process is unlikely to affect the dissolution rate? 1. Binders 2. Granulation protocol 3. Residual moisture 4. Granule size 5. Coating 6. Pressure in the punch 7. Lubricants 8. Disintegrants 9. Colorants
9. Colorants
55
instability of solid dosage forms are typically caused by (3)
1 humidity 2 temperature 3 light
56
stability is defined as what by the ICH guidelines
Time during which API/FPP retains properties
57
accelerated study is defined as what by the ICH guidelines
High Temp/RelativeHumidity → predict long-term stability
58
long-term study is defined as what by the ICH guidelines
Real storage conditions
59
ongoing study is defined as what by the ICH guidelines
Monitors production batches post-approval
60
stress testing is defined as what by the ICH guidelines
Severe conditions to find degradation pathways
61
stress testing of API in solution testing periods: a. in various pH at room temp b. in H2O2 (2wks/ 24hours)
a. 2 weeks b. 24 hours
62
long term stability tests last for:
12-6 months
63
intermediate and acceleration stability tests last for:
6 months
64
how can we determine the expiration date/ shelf life from accelerated stability test?
looking at the graph, use predicted line to see the point at which 5% of the drug has been lost
65
stability testing is required for a. IND b. NDA c. ANDA d. b and c e. all of the above
e. all of the above
66
forced degradation:
identifies degradation products, impurities, and toxic byproducts (e.g., nitrosamines in ranitidine)
67
Why do enteric-coated forms need anionic polymers?
Enteric-coated forms need anionic polymers because of their ability to become protonated and, therefore, become insoluble at gastric pH
68
Which enteric coating polymer will be more soluble at low pH, with sulfate groups or carboxylic groups? Why? Why is a polymer with sulfate groups not the best option?
carboxylic groups Sulfates are strong acids, allowing such polymers to remain ionized and soluble throughout the gastrointestinal tract.
69
If tablets were coated with a positively charged polymer, how would they be called?
If tablets were coated with a positively charged polymer, they would be called mucoadhesive because of the ability of the positive charge to bind to negatively charged mucin.
70
What is the purpose of achieving an extended-release profile?
The purpose of achieving an extended-release profile is to provide a more consistent drug delivery and maintain therapeutic levels of the drug in the body for a longer duration.
71
Why would a zero-order release be advantageous over a first-order one?
Zero-order release is advantageous over first-order because it provides a constant drug release rate, which can result in a better blood profile and reduce the frequency of dosing.
72
A first-order release tablet results in the release of 50% of the drug in 30 min. How much drug will be released after 90 min?
30 min – 50%, 60 min, 75%, 90 min, 87.5%.
73
What is the absorption window, and why is it important to consider controlled-release dosage forms?
The absorption window is the area in the gastrointestinal tract where the drug is most effectively absorbed. Designing controlled-release dosage forms to release the drug within the absorption window can optimize drug delivery and increase efficacy.
74
What is the physical principle of OROS? Bonus question: can you think of an alternative zero-order release mechanism that involves the body’s physiology?
The physical principle of OROS (osmotic controlled-release oral delivery system) is that osmotic pressure drives the release of the drug from the tablet. The tablet has a semi-permeable membrane that allows water to enter and creates pressure that pushes the drug out of the tablet.
75
What is the natural way to slow down drug release if the absorption window is in the stomach?
Food (especially fatty meals) can slow down drug release by delaying gastric emptying. This can be useful when the absorption window is in the stomach or the duodenum.
76
Please describe the problems related to the polymer coating of tablets
Problems related to the polymer coating of tablets can include inadequate coating, leading to inconsistent drug release, uneven coating, leading to variable drug absorption, and degradation of the coating material over time.
77
According to Noyes Whitney equation, which parameters control the dissolution process or a drug particle?
According to the Noyes-Whitney equation, the dissolution process is controlled by the surface area of the drug, the diffusion coefficient of the drug in the solvent, and the thickness of the boundary layer
78
Describe the uses of the dissolution test in the pharmaceutical industry. Why is the dissolution test widely used for tablet dosage forms?
The dissolution test is widely used in the pharmaceutical industry to assess the quality and consistency of tablet dosage forms. It can detect changes in the manufacturing process and ensure that generic tablets are equivalent to the original tablets in terms of drug release and absorption
79
What is the purpose of the forced degradation study?
The purpose of the forced degradation study is to identify the potential degradation products of a drug or dosage form under various conditions, such as exposure to heat, light, moisture, or acidic/basic environments. This information can be used to develop appropriate storage conditions and to ensure the stability of the drug over time.
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