Pharmacokinetics Biopharmaceutics (1/3)

Question 1

Define: Biopharmaceutics

Answer 1

Study of how physiochemical properties of APIs, dosage forms and routes of administration affect rate and extent of API action

Question 2

Define: Pharmacodynamics

Answer 2

What the API does to the body

Question 3

Define: Pharmacokinetics

Answer 3

What the body does to the API

Question 4

How does absorption affect the API?

Answer 4

Transports API from site of administration to the plasma

Question 5

How does distribution affect the API?

Answer 5

Transports API from plasma to the site of action = clinical effect

Question 6

How does elimination effect the API?

Answer 6

API metabolised and the unchanged API is excreted

Question 7

List the 4 stages of absorption

Answer 7

Disintegration (from tablet to granules)
Further disintegration (to particles)
Dissolves (API in solution - can be absorbed in the bloodstream)
Carried to site of action

Question 8

What’s the difference between dissolution rate and solubility?

Answer 8

Solubility = fixed value (in a given solvent, at a given temperature)
Dissolution rate = varies with many factors:
Physical form of API e.g. polymorph
Particle size of API
Stirring

Question 9

Which stage of absorption does a suspension not undergo?

Answer 9

The disintegration stage - API particles can begin dissolving straight away

Question 10

Which stages of absorption does a solution not undergo?

Answer 10

The disintegration and the dissolution stages - as API is already in solution (therefore faster acting)

Question 11

Define: Bioavailability

Answer 11

The fraction of an administered dose that reaches the bloodstream (F)
IV = 100% bioavailability

Question 12

Why do APIs absorbed from the GIT have a lower bioavailability than those administered by IV?

Answer 12

Those administered orally undergo 1st pass metabolism by the liver

Question 13

What is the formula to calculate bioavailability (F)?

Answer 13

F = amount (route)/amount (IV)

F(IV) = 1 always

Question 14

List 2 factors about a drug which can stop the API from being absorbed in the GIT

Answer 14

The dosage form does not release the API (so it cannot be absorbed)
The API does not dissolve quickly enough if released so it will pass through the GIT

Question 15

List 2 consequences of a drug having poor bioavailability

Answer 15

A lot of API is required for the little amount that is absorbed to have an effect (large dosage form, inconvenient, inefficient, expensive)
Patient-to-patient variation in absorption will have a bigger effect than with APIs that are well-absorbed

Question 16

What is the therapeutic range?

Answer 16

The window between the minimum effective concentration and the maximum safe concentration of a drug

Question 17

List 3 roles of pharmaceutics

Answer 17

To design a dosage form that:
Gives the desired pharmacokinetic profile
Is safe and convenient for patients to take
Minimises side effects of the API