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Pharmacokinetics > IVIVC > Flashcards

IVIVC Flashcards

1
Q

Innovator = ?

A

Brand (ex. Advil)

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2
Q

Describe bioavailability studies

A
  • need to do Ba for every optimized formulation (past)
  • ensure that the optimized “new formulation” is similar to the “old formulation” of the same drug
  • lengthy and costly
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3
Q

In vitro = ?

A

within the glass

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4
Q

In vivo = ?

A

within the living

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5
Q

What the concept between IVIVC?

A

based on developing a relationship between dissolution and bioavailability

*a predictive mathematical model describing the relationship between an in vitro property of a dosage form and relevant in vivo response

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6
Q

In vitro property is ?

A

the rate of drug dissolution or release

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7
Q

In vivo response is ?

A

the plasma drug concentration or amount of drug absorbed (bioavailability)

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8
Q

Why was IVIVC developed?

A

To minimize the need for additional bioavailability studies as part of the formulation design

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9
Q

What is the difference between solubility and dissolution?

A

Solubility: the number of mg that can be dissolved in a certain volume (mg/mL)

Dissolution: the rate at which the mg dissolve into the certain volume (mg/time)

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10
Q

Noyes-Whitney Equation:

What does D stand for?

A

diffusion coefficient (diffusivity) of the drug

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11
Q

Noyes-Whitney Equation:

What does the S stand for?

A

surface area of the drug

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12
Q

Noyes-Whitney Equation:

What does the h stand for?

A

thickness of the diffusion layer liquid film

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13
Q

Noyes-Whitney Equation:

What does the Cs stand for?

A

saturation solubility of the drug

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14
Q

Noyes-Whitney Equation:

What does C stand for?

A

concentration of the drug in the bulk medium

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15
Q

What are some dosage forms that require a dissolution test?

A

tablets, capsules, ointments, creams, suppositories, pessaries, transdermal and implants

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16
Q

What is selection of testing conditions based on?

A
  • Type of dosage form (tablets, suspensions, transdermal)
  • Release pattern (immediate vs modified release)
  • Physiology of the site of administration (GIT, skin, buccal, sublingual)
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17
Q

Dissolution apparatus 1

A

Rotating basket:

-disadvantage is that dosage may clog in mesh screen

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18
Q

Dissolution apparatus 2

A

Paddle:

  • sinkers used for floating pills
  • disadvantage is cone formation
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19
Q

Apparatus 1 & 2 are the most used for oral dosage forms:

Advantages ?

A
  • widely accepted apparatus for dissolution test
  • apparatus of first choice for solid oral dosage forms
  • standardized
  • easy to operate
  • robust
  • broad experience
20
Q

Apparatus 1 & 2 are the most used for oral dosage forms:

Disadvantages ?

A
  • limited volume
  • simulation of GI transit not possible
  • hydrodynamic conditions not known
21
Q

Dissolution apparatus 3

A

Reciprocating cylinder:

  • moves up and down, better simulates GI tract)
  • originally used for extended release products
22
Q

Dissolution apparatus 4

A

Flow Through Cell:

  • adjust flow rate with a pump
  • for solids, semi solids and liquids
  • continuous flow rate or re-circlate media
23
Q

Dissolution apparatus 4:

Advantages ?

A
  • no limitation of media volume
  • suitable for drugs with low solubility
  • gentle hydrodynamic conditions
  • simulation of the GI transit
  • suitable for special dosage forms (powders, granules, implants)
24
Q

Dissolution apparatus 4:

Disadvantages ?

A
  • limited experience

- pump precision influences the results

25
Q

What are apparatuses 5, 6, and 7 used for?

A
  • specialized dosage forms (extended release and transdermals)
  • Advantage: change medium pH and flow rate
26
Q

Dissolution apparatus 5

A

Paddle over disk:

  • Better for floaters
  • Also good for transdermal patches, ointments, emulsions, bolus
27
Q

Dissolution apparatus 6

A

Cylinder:

  • good for patches that are too big for apparatus 5
  • this one rotates
28
Q

Dissolution apparatus 7

A

Reciprocating holder:

  • similar to apparatus 6 but instead of rotating, it reciprocates (up and down)
  • simulates GI tract more accurately
29
Q

How is in vivo absorption assessed?

A

By calculating:

  • AUC
  • Cmax
  • Tmax
30
Q

IVIVC development:

Step 1 = ?

A

Dissolution

31
Q

IVIV development:

Step 2 = ?

A

Permeability

32
Q

What is the key to developing an IVIVC?

A

to identify a dissolution test that is descriptive of the in vivo absorption of the test compound

33
Q

What is permeability?

A

The ability of the drug to penetrate across a membrane into the systemic circulation

34
Q

What does the extent of permeation and ultimately absorption depend on?

A
  • the physicochemical properties of the drug

- blood perfusion

35
Q

What are the 4 levels of strength of the correlation?

A

Level A
Level B
Level C
Multiple Level C

36
Q

Describe Level A correlation

A
  • point to point relationship between intro dissolution rate and in vivo input rate of the drug from the dosage form
  • utilize all of the “dissolution” and “plasma level” data available
  • strongest level
37
Q

Describe Level B correlation

A
  • not a point to point relationship

- compares means

38
Q

Describe Level C correlation

A
  • a single time point correlation
  • one dissolution time point is compared to one in vivo parameter
  • does not reflect the entire shape of the plasma drug concentration curve
  • this is the weakest level
39
Q

Describe multiple level C correlation

A
  • extension of level C correlation
  • relates one or several in vivo parameters to in vitro drug release at several time points
  • should be baed on at least 3 dissolution time points covering the early, middle, and late stage of the dissolution profile
40
Q

BCS is a tool to classify drugs based on their ??

A

solubility and intestinal permeability

41
Q

Class 1 BCS

A

high solubility

high permeability

42
Q

Class 2 BCS

A

low solubility

high permeability

43
Q

Class 3 BCS

A

high solubility

low permeability

44
Q

Class 4 BCS

A

low solubility

low permeability

45
Q

When combined with the dissolution of the drug product, the BCS takes into account 3 major factors that govern the rate and extent of drug absorption from solid oral dosage forms:
What are the 3 major factors?

A
  • dissolution
  • solubility
  • intestinal permeability
46
Q

When is IVIVC most likely predictable?

A

When the rate limiting step is drug release/dissolution

ex. highly permeable and poorly soluble (Class 2)

47
Q

When is IVIVC limited?

A

1) When the rate limiting step is gastric emptying rate

2) When the rate limiting step in absorption is low permeability

Pharmacokinetics (12 decks)

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