Pharmacokinetics Biopharmaceutics (1/3) Flashcards Preview

PM2B Spring Amy L > Pharmacokinetics Biopharmaceutics (1/3) > Flashcards

Flashcards in Pharmacokinetics Biopharmaceutics (1/3) Deck (17):

Define: Biopharmaceutics

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


Define: Pharmacodynamics

What the API does to the body


Define: Pharmacokinetics

What the body does to the API


How does absorption affect the API?

Transports API from site of administration to the plasma


How does distribution affect the API?

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


How does elimination effect the API?

API metabolised and the unchanged API is excreted


List the 4 stages of absorption

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


What's the difference between dissolution rate and solubility?

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


Which stage of absorption does a suspension not undergo?

The disintegration stage - API particles can begin dissolving straight away


Which stages of absorption does a solution not undergo?

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


Define: Bioavailability

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


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

Those administered orally undergo 1st pass metabolism by the liver


What is the formula to calculate bioavailability (F)?

F = amount (route)/amount (IV)

F(IV) = 1 always


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

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


List 2 consequences of a drug having poor bioavailability

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


What is the therapeutic range?

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


List 3 roles of pharmaceutics

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