8. Pharmacokinetic calculations, principles of pharmacotherapy (bioavailability, loading dose, maintenance dose)

Question 1

One-compartment vs two-compartment model

Answer 1

In one compartment model only elimination is considered. In 2 compartment disribution + elimination

Question 2

Apparent volume distribution (Vd)

Answer 2

Ratio of the total amount of drug in the body to the plasma concentration of the drugs. Vd = D/C

Lower Vd -› drug distributed mainly in blood
Higher Vd -› better distibution of the drug in the body

Question 3

Difference in blood concentration of the drug in IM and SC administration

Answer 3

SC -› drug stays in the plasma for longer period of time

Question 4

Bioavalability (F) -?

Answer 4

is the ration between two AUC (area under curve)

reflects the actual body exposure to drug after administration. (comparing it to IV data)

F = AUC(x - way of adm) x D(iv) / AUC(iv) x D(x)

Question 5

Clearance (Cl) - ?

Answer 5

volume of plasma that is cleared of drug per time unit (ml/min or l/hour)

Question 6

Loading dose

Answer 6

Dose given with one adminisration (or repeated few times quickly) with which the desired drug consentration can be reached immediately

Question 7

Maintenace dose

Answer 7

The dose needed to maintain the concentration within the theraupetic window when given repeatedly at a constant interval

Question 8

When is steady state reached?

Answer 8

Between 4 and 5 administration. Time to steady state is independent of dosage