Bioavailbillty (w25)

Question 1

In relation to bioavailability, what does IV administration mean ?

Answer 1

The entire dose reaches the systemic circulation, i.e. 100% bioavailability (F)

Question 2

What can bioavailability depend on ?

Answer 2

Can depend upon permeability of the biological membrane, drug properties,and other route-dependent factors, e.g. stomach contents for oral route

Question 3

What is F ?

Answer 3

fraction of administered dose of drug which reaches system circulation (intact)

Question 4

What is Naloxone ?

Answer 4

• drug used to combat opiate overdose
• rapid onset is required and undergoes first pass metabolism

Question 5

How is absolute bioavailability (F) calculated ?

Answer 5

Absolute bioavailability (F) is calculated by comparing the amount absorbed by one route, e.g. oral, to the i.v. route

Question 6

What might be a cause of reduced bioavailability ?

Answer 6

The reduced bioavailability may be due to incomplete absorption and/or first-pass clearance

Question 7

How is relative bioavailability (Frel) calculated ?

Answer 7

Relative bioavailability (Frel) is calculated by comparing the amount absorbed from a test formulation, e.g. an oral drug solution, to a standard formulation such as a tablet

Question 8

What is relative bioavailability (F rel) often used to measure ?

Answer 8

Frel is often used to measure changes in formulation parameters, e.g. dosage form, excipients, processes

Question 9

What is the salt factor (S) or the salt concentration factor ?

Answer 9

The salt factor (S) or salt correction factor is the fraction of the dose (which may be in the form of a salt or ester) that is the active drug